RU2428251C1 - Catalyst for synthesis of carboxylic esters, preparation method thereof and method for synthesis of carboxylic esters - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to catalysts for synthesis of carboxylic esters. Described is a catalyst for synthesis of a carboxylic ester through reaction of (a) an aldehyde and alcohol, or (b) one or more types of alcohols in the presence of oxygen, the catalyst containing: nickel oxide; and X, where X is at least one element selected from a group comprising palladium, platinum, ruthenium, gold, silver and copper, deposited on a carrier in atomic ratio Ni/(Ni+X) from 0.20 to 0.99. Described is a method of preparing a catalyst for synthesis of a carboxylic ester, involving a first step for producing a catalyst precursor by depositing nickel and component X, where X is at least one element selected from a group comprising palladium, platinum, ruthenium, gold, silver and copper on a carrier through neutralisation of an acidic solution of a soluble metal salt containing nickel and X; and a second step for oxidising nickel via thermal treatment of the obtained catalyst precursor, where the atomic ratio Ni/(Ni+X) ranges from 0.20 to 0.99. Described also is a method for synthesis of a carboxylic ester, involving a step for reaction of the described catalyst with (a) an aldehyde and alcohol, or (b) one or more types of alcohols, in the presence of oxygen.

EFFECT: active catalyst for synthesis of a carboxylic ester is obtained.

17 cl, 5 tbl, 5 dwg, 48 ex

Description

Technical field

The present invention relates to a catalyst for producing carboxylic acid esters by reacting an aldehyde and an alcohol, or one or more kinds of alcohols in the presence of oxygen, to a method for producing a catalyst and to a method for producing carboxylic acid esters using a catalyst.

State of the art

A method for producing commercial carboxylic acid esters in the case of methyl methacrylate, for example, may include a method in which methacrylic acid is obtained by oxidizing methacrolein with oxygen, followed by reacting methacrylic acid with methanol to obtain methyl methacrylate. However, the heteropoly acid catalyst used in the methacrylic acid production step by the oxidation of methacrolein has thermal stability problems and gradually decomposes under the reaction temperature conditions. In addition, the yield also remains insufficient, thus providing an opportunity for improving the industrial catalyst.

On the other hand, the direct metaprocess of producing methyl methacrylate or methyl acrylate in one step by reacting methacrolein or acrolein with methanol and molecular oxygen is a simple method that does not require the separation of readily polymerizable methacrylic acid or acrylic acid and is currently attracting attention due to the higher yield of methyl methacrylate according to Compared to the above method.

In this method, a catalyst containing predominantly palladium is used as a catalyst. However, in the process of producing methyl methacrylate or methyl acrylate in one step by reacting methacrolein or acrolein with methanol and molecular oxygen, since methacrolein or acrolein is an unsaturated aldehyde, numerous acetals of the unsaturated aldehyde and alkoxy form, formed by the addition of alcohol to unsaturated bonds, form , which also leads to a problem associated with the formation of gaseous carbon dioxide, which is the final oxidation product (see patent th document 1).

In this regard, catalyst modifications have been created to overcome these problems. For example, it was reported that the above problems related to the formation of by-products have been resolved and the carboxylic acid ester can be obtained in high yield by using a catalyst containing an intermetallic compound having palladium and at least one element selected from a group consisting of lead, mercury, bismuth and thallium, or a catalyst containing an alkali metal compound or an alkaline earth metal compound (see Patent Document 2).

On the other hand, although it has been believed for a long time that the catalysts used in this process require the presence of a catalyst containing palladium, lately, the use of catalysts that contain a noble metal such as ruthenium or gold supported on a support has been reported. . Specific examples of such methods include the use of a catalyst in which gold is supported on a support (see Patent Document 3), or the use of a catalyst containing ruthenium (see Patent Document 4) in the process of producing a carboxylic acid ester by reacting an aldehyde and an alcohol in the presence of oxygen-containing gas.

Patent Document 1: Japanese Patent Publication No. S45-34368

Patent Document 2: Japanese Patent Publication No. S62-7902

Patent Document 3: Japanese Patent Application Laid-Open No. 2000-154164

Patent Document 4: Japanese Patent Application Laid-Open No. 2001-220367.

Description of the invention

Tasks Solved by the Present Invention

Be that as it may, in each of the known methods described above, the selectivity of the carboxylic acid esters obtained and the activity of the catalyst are insufficient, and since expensive noble metals such as palladium, ruthenium and gold are used in large quantities on a support , the economic burden arising from increased costs for the production of the catalyst is large, which complicates, therefore, the consideration of these methods as advantageous on an industrial scale.

In addition, since palladium, ruthenium and gold, which are used in the above production methods, are representatives of noble metals, they are expensive, and they are often used as a catalyst component by dispersion and deposition on a carrier, thereby making, in such cases, extremely important media choice.

Setting the task of practical application of the industrial method, as a result of extensive studies of catalysts supported by composite nanoparticles containing oxidized nickel and X (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper), the authors of the present invention made the undoubted conclusion that the catalyst, satisfactory in terms of its service life, is not necessarily obtained if activated coal, calcium carbonate, alumina, silica or silica with titanium dioxide as a carrier. Namely, in the case of participation in the reaction of the catalyst in the form of a suspension in a commonly used industrial stirred tank reactor or bubbler reactor in the form of a tower or the like, the mechanical strength was insufficient and peeling of nickel and component X, which are components of the catalyst, was observed in the case of activated carbon. In addition, although alumina has high mechanical strength, the strength of the carrier decreases due to corrosion by acidic substances, examples of which are typical reaction by-products, methacrylic acid and acrylic acid, which leads to the disadvantage of easier peeling of Nickel and component X, which are catalyst components. The use of calcium carbonate for the carrier leads to an even greater sensitivity to corrosion under the influence of acidic substances than in the case of aluminum oxide, making it, therefore, unsuitable for industrial use. In the case of silicon oxide or silicon oxide with titanium dioxide, part of the silicon oxide is gradually corroded by water introduced during the process or by water obtained as a by-product of the reaction, which leads to leaching of silicon oxide, while peeling and leaching of nickel and component X, which are the components of the catalyst. Therefore, there are problems associated with whether these substances will remain stable over a long period of use. In addition, there are also problems with mechanical strength, which is lower than that of the aforementioned alumina.

On the other hand, research has been reported on methods for producing silica gel and studies on the use of high temperature sintering to modify silica gel to increase the mechanical strength and corrosion resistance of silicon oxide. However, no examples were reported of successfully increasing mechanical strength and resistance to hydrolysis without compromising the functional properties of the catalyst. For example, it is known that quartz, which is a type of silica-based substance, is solid, has high mechanical strength and is highly resistant to hydrolysis. However, in the case of using quartz as a carrier, although the mechanical strength and corrosion resistance are markedly improved, this also leads to a decrease in the specific surface (1 m ² / g or less), and since this prevents the metal catalyst from being loaded in the form of fine particles in a finely divided state, a problem arises with the extremely low reactivity of the resulting catalyst.

Given this technical level, as described above, there is currently a need for a catalyst carrier that has high mechanical strength and is physically stable, and also has a large surface area suitable for use as a catalyst carrier, exhibits sufficient corrosion resistance to to a characteristic liquid-phase reaction in the form of a synthesis reaction of a carboxylic acid ester in the presence of oxygen and is capable of stable deposition of nickel and component X, which are the active components of the catalyst, over a long period of time.

In view of the foregoing, it is an object of the present invention to provide a catalyst for producing a carboxylic acid ester by reacting an aldehyde and an alcohol, or one or more types of alcohols, in the presence of oxygen, in which a high level of reactivity is maintained by using catalyst as the main components stable metal elements with excellent reactivity, instead of the usual expensive noble metals, creating a method for teachings of such catalyst and a process for producing carboxylic acid esters using such a catalyst.

Problem Solving Tools

As a result of extensive research to solve the above problems, the authors of the present invention found that the above problems can be solved using a catalyst for producing a carboxylic acid ester in which oxidized nickel and X (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) is applied to the carrier in the range of the atomic ratio Ni / (Ni + X) from 0.20 to 0.99.

Namely, the invention is described below.

[1] A catalyst for producing a carboxylic acid ester by reacting (a) an aldehyde and an alcohol, or (b) one or more kinds of alcohols, in the presence of oxygen, containing:

oxidized nickel; and

X (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) deposited on a carrier in the range of the atomic ratio Ni / (Ni + X) from 0, 20 to 0.99.

[2] A catalyst for producing a carboxylic acid ester according to [1], comprising a composite nanoparticle consisting of oxidized nickel and X (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper).

[3] A catalyst for producing a carboxylic acid ester according to [2], wherein the composite nanoparticle is a particle having X in its core and the surface of the core is coated with oxidized nickel.

[4] A catalyst for producing a carboxylic acid ester according to [2] or [3] in which, in addition to the composite nanoparticle, independently oxidized nickel is applied to the support.

[5] A catalyst for producing a carboxylic acid ester according to any one of [1] to [4], wherein the oxidized nickel is nickel oxide and / or a nickel containing oxide.

[6] A catalyst for producing a carboxylic acid ester according to any one of [1] to [5], wherein the support is a silica-based aluminum composition that contains silica and alumina, and the amount of aluminum is in the range of 1 up to 30 mol.%, calculated on the total molar amount of silicon and aluminum.

[7] The catalyst for producing a carboxylic acid ester according to [6], wherein the carrier further comprises at least one kind of a base metal component selected from the group consisting of alkali metal, alkaline earth metal and rare earth metal.

[8] A catalyst for producing a carboxylic acid ester according to [6] or [7], in which the ratio of nickel and alumina is from 0.01 to 1.0, based on the atomic ratio of Ni / Al.

[9] A catalyst for producing a carboxylic acid ester according to [7] or [8], in which the ratio of nickel to base metal component is from 0.01 to 1.2, based on the atomic ratio Ni / (alkali metal + alkaline earth metal + rare earth metal).

[10] A catalyst for producing a carboxylic acid ester according to any one of [1] to [9], wherein the carrier is a composition comprising silica, alumina and magnesium oxide, and contains from 42 to 90 mol%. silicon, from 5.5 to 38 mol.% aluminum and from 4 to 38 mol.% magnesium, calculated on the total molar amount of silicon, aluminum and magnesium.

[11] A catalyst for producing a carboxylic acid ester according to [10], wherein the ratio of nickel to alumina is from 0.01 to 1.0, based on the atomic ratio of Ni / Al, and the ratio of nickel to magnesium oxide is from 0.01 to 1.2, based on the atomic ratio of Ni / Mg.

[12] A catalyst for producing a carboxylic acid ester according to any one of [1] to [11], wherein the specific surface area is from 20 to 350 m ² / g, the pore diameter with maximum repeatability is from 3 to 50 nm, volume the pore is from 0.1 to 1.0 ml / g and the particle diameter is from 10 to 200 microns.

[13] A method for producing a catalyst for producing a carboxylic acid ester, comprising:

the first stage of the preparation of the catalyst precursor by precipitation of nickel and component X (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) on a support by neutralizing an acid solution of a soluble metal salt, containing nickel and X; and

the second stage of nickel oxidation by heat treatment of the resulting catalyst precursor.

[14] A method for producing a carboxylic acid ester, comprising the step of reacting a catalyst to produce a carboxylic acid ester according to any one of [1] to [12] with (a) an aldehyde and an alcohol, or (b) one or more kinds of alcohols, in the presence of oxygen.

[15] The method for producing a carboxylic acid ester according to [14], wherein the aldehyde is a compound selected from acrolein, methacrolein, and mixtures thereof.

[16] The method for producing a carboxylic acid ester according to [14], wherein the aldehyde is a compound selected from acrolein, methacrolein and mixtures thereof, and the alcohol is methanol.

[17] The method for producing a carboxylic acid ester according to [14], wherein one type of alcohol is ethylene glycol and the other type of alcohol is methanol.

Advantages of the Invention

In accordance with this invention, a catalyst for producing a carboxylic acid ester can be created that maintains a high level of reactivity by using a stable nickel compound having excellent reactivity for the main catalyst component instead of the usual expensive noble metals, a method for producing such a catalyst, and a method for preparing a carboxylic acid ester using such a catalyst.

Brief Description of the Drawings

Figure 1 shows a photomicrograph obtained using a transmission electron microscope (TEM, bright field image), a catalyst to obtain a carboxylic ester of example 4;

Figure 2 shows an enlarged micrograph shown in figure 1, and the image of its part, obtained using fast Fourier transform (FFT);

Figure 3 shows a photomicrograph obtained using a scanning transmission electron microscope (STEM, bright field image) of a catalyst for preparing the carboxylic acid ester of Example 4 together with the results of the composition analysis at the indicated points by energy dispersive X-ray spectroscopy;

Figure 4 shows the micrographs obtained using a scanning transmission electron microscope (STEM, bright field image), a catalyst for the production of carboxylic acid ester of Example 4 together with a linear profile of its composition obtained by energy dispersive x-ray spectroscopy; and

Figure 5 shows a graph illustrating the results of the analysis by spectroscopy in the UV and visible regions of the catalyst to obtain the carboxylic ester of example 4.

Best Mode for Carrying Out the Invention

The following description provides a detailed explanation of the best embodiment of the present invention (the reference to which is given as “this embodiment”). In addition, the invention is not limited to the embodiments presented below, and may be practiced with some variation in various ways within the scope of the invention.

The catalyst for producing a carboxylic acid ester according to this embodiment is a catalyst for producing a carboxylic acid ester by reacting (a) an aldehyde and an alcohol, or (b) one or more kinds of alcohols in the presence of oxygen in which oxidized nickel and X (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) are supported on a support in the range of the atomic ratio Ni / (Ni + X) from 0.20 to 0.99.

The catalyst for producing a carboxylic acid ester in accordance with this embodiment preferably further comprises composite nanoparticles consisting of oxidized nickel and X (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper).

The oxidized nickel is preferably nickel oxide formed by the bonding of nickel and oxygen (for example, Ni ₂ O, NiO, NiO ₂ , Ni ₃ O ₄ or Ni ₂ O ₃ ), or a complex oxide containing nickel, for example, a solid nickel oxide compound a solution or a mixture thereof, and formed by the binding of nickel and X and / or one or more kinds of another metal element and oxygen.

The term "nickel oxide", as used herein, refers to a compound containing nickel and oxygen. Nickel oxide includes Ni ₂ O, NiO, NiO ₂ , Ni ₃ O ₄ or Ni ₂ O ₃ , or hydrates of the above compounds, nickel hydroperoxides containing an OOH group, or nickel peroxides containing an O ₂ group, or a mixture of the above compounds, etc. P.

In addition, the term “complex oxide” as used herein refers to an oxide containing two or more kinds of metals. The term “complex oxide” refers to an oxide in which two or more kinds of metal oxides form a compound, and although this includes double oxides in which ions of oxo acids are not present as structural units (such as nickel oxides such as perovskite or spinel), it also includes all oxides in a broader sense than double oxides in which two or more kinds of metals are combined. Oxides in which two or more kinds of metal oxides form a solid solution also fall into the range of complex oxides.

The following is an explanation of the action that results in an extremely high catalyst efficiency due to the deposition of oxidized nickel and X (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) on the carrier in the range of the atomic ratio Ni / (Ni + X) from 0.20 to 0.99.

The inventors of the present invention have found that the catalytic activity inherent in nickel oxides having oxidative esterification activity is achieved by combining nickel oxide and X, and that an unusually high catalyst efficiency is not exhibited by catalysts consisting of each individual component. This can be attributed to the unique effect resulting from the combination of nickel oxide and X, and is believed to be the result of the formation of a new catalytic action, which is completely different from the action of catalysts consisting of each individual component, due, for example, to the formation of a binary functional catalyst or new active components between both metal components. Based on this new concept, in the case of deposition of oxidized nickel and X on a support in a finely dispersed state, in particular, the characteristics of the catalyst could be realized, radically different from those obtained for catalysts in accordance with the prior art.

In past years, nanoparticles, which have attracted considerable attention due to advances made in the technology of synthesis of ultrafine particles, have been recognized as the main material in the field of nanotechnology, and their research is progressing throughout the world. Nanoparticles having a particle diameter of 100 nm or less differ from large particles in that they have a high proportion of the surface metal element among the metal elements that make up the nanoparticles, resulting in the surface area of the metal element per unit mass rapidly increasing with a decrease in particle size. Examples of nanoparticles known in the field of catalytic materials may include metal nanoparticles, such as platinum, palladium, ruthenium, rhodium, gold, silver and copper nanoparticles, or metal oxide nanoparticles, such as iron oxide, cobalt oxide, nickel oxide, zinc oxide nanoparticles titanium oxide, zirconium oxide, indium oxide, alumina and silicon oxide, and these nanoparticles attract attention as heterogeneous catalytic materials. Namely, one of the reasons for the increasing attention paid to the use of nanoparticles in catalytic materials is that, since the factor that contributes to the catalytic effect is limited to the metal element present on the surface of the particles, when applied at the nanoscale, the surface area on the unit mass of the metal element involved in the reaction (specific surface) increases, whereby the activity of the catalyst is calculated based on the mass of the metal ementa. Changes in the catalytic effect attributed to the size of the nanoparticles are thus commonly known as “particle size effects”.

On the other hand, there are also cases in which new effects appear, in addition to these particle size effects. For example, the action of binary metal nanoparticles is known as one of the factors that have a significant effect on the catalytic effect of nanoparticles. This action refers to an effect that cannot be exerted by a single metal component and appears only as a result of association. Alloys, referred to in accordance with the prior art, are a well-known example of this (binary metal nanoparticles not only refer to the case of elemental components being metals, but also include cases in which metal compounds or metals and metal compounds are combined. Although the size and particle shape are the main parameters controlled in the case of nanoparticles consisting of a single element, in the case of nanoparticles consisting of two or more kinds of elementary components On the other hand, additional controlled parameters include composition, crystalline structure and phase structure (for example, the structure of an alloy or solid solution in which the crystalline positions are randomly occupied by chemical components, the core-shell structure in which each chemical component is separated in the form of concentric spheres, anisotropic phase a structure in which the phases are separated in an anisotropic manner, and a structure with heterophilic bonds in which both chemical components are present next to each other m on the surface of particles). Namely, as a result of using the structure of the binary compound, changes occur in the mass of the metal component, leading to the manifestation of chemical and electronic properties, which are distinctly different from single nanoparticles. Thus, it was found that binary metal nanoparticles exhibit new catalytic, magnetic and optical properties that are not found in nanoparticles consisting of a single type of metal element, and methods have been developed for using them, in addition to catalysts, in various fields, such as electronic materials , medicine and biotechnology.

The authors of this invention conducted a large-scale search for materials with the aim of creating catalysts with high selectivity and activity in the production of carboxylic acid esters, as well as having an inexpensive metal element with high reactivity as their main component in order to replace them with expensive noble metals in accordance with the known prior art. Attention was focused on nickel as an element having properties that are similar to those of noble metals, and extensive studies have been conducted on the correlation between its chemical state and reactivity, which led to the completion of this invention. Namely, as described previously, the catalyst of this embodiment contains oxidized nickel and X as a binary metallochemical component (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) deposited on a carrier in the range of the atomic ratio Ni / (Ni + X) from 0.20 to 0.99. The catalyst of this embodiment preferably further comprises nanoparticles consisting of oxidized nickel and X (where X is at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper). The following is a more detailed explanation of such a catalyst.

When the inventors of the present invention used nickel oxides, which are currently attracting attention as a catalyst for the oxidation of alcohol, it was first found that, despite the low level of activity, even one nickel oxide (NiO) is active in the formation of a carboxylic acid ester . Moreover, as a result of additional studies, the authors of the present invention clearly showed that highly oxidized nickel peroxide (NiO ₂ ) exhibits higher performance than nickel oxide. On the other hand, activity was not observed when using only metallic nickel (Ni).

Based on this information, it was suggested that an inexpensive metal element, nickel, can be used as the main component of the catalyst. Then, the authors of the present invention investigated the addition of various metal elements to nickel oxide by changing the oxidized state of nickel, hoping to find out the possibility of further improving the characteristics of the catalyst by adjusting the oxidized state of nickel and applying the active component to the support in a finely divided state. As a result, the inventors of the present invention found that by applying oxidized nickel and at least one metal component selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver, and copper onto a support in a finely divided state in the range of the atomic ratio Ni / (Ni + X) from 0.20 to 0.99, the nickel oxide is converted from the normal oxidized state to the highly oxidized nickel oxide, thereby significantly increasing activity and selectivity compared to catalysts, consisting of by them solely from each element, or by catalysts in which the atomic ratio Ni / (Ni + X) is outside the above range.

For example, when gold is selected as X and nickel oxide and gold are deposited on the support in a finely divided state, a very high activity of the catalyst appears. It has been observed that this catalyst exhibits a higher selectivity in the preparation of a carboxylic acid ester compared to catalysts in which only one nickel oxide or only gold is supported, and a significant increase in activity has been observed for a specific Ni / (Ni + Au) ratio. With respect to the activity of the catalyst per metal atom, the activity of (Ni + Au) during the formation of the carboxylic acid ester is higher than the activity of the catalysts consisting of each component separately, and the functioning of the catalyst related to their combination, largely depends on the applied nickel and gold compositions. This is supposed to be due to the presence of a ratio optimal for the formation of the oxidized state of nickel, which is optimal for the reaction. Thus, as a result of applying two components, nickel oxide and gold, to the carrier in a dispersed state, noticeable combining effects appeared, which could not be predicted by a simple summation of the effects created by each component individually.

In the above catalyst, oxidized nickel and gold are supported on a support in a finely divided state, and both components are combined at a nanoscale. Based on the results of observations using a transmission electron microscope / scanning transmission electron microscope (TEM / STEM), almost spherical nanoparticles having a particle size distribution of 2 to 3 nm in diameter were deposited uniformly dispersed on a carrier. Based on elemental analysis of nanoparticles by energy dispersive X-ray spectroscopy (EDS), both nickel and gold are present in all particles and, as observed, are in the form of gold nanoparticles, the surface of which is coated with nickel. In addition, a separate nickel component was detected supported on a carrier, in addition to nanoparticles containing nickel and gold.

According to the results of X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD powder), although gold is present as a crystalline metal, nickel is believed to be present as an amorphous oxide with a valence of 2.

Based on the results of spectroscopy in the UV and visible spectral regions, providing the possibility of observing changes in electronic excited states, it was found that the combination of oxidized nickel oxide and gold causes the absorption peak of surface plasmons to disappear (at about 530 nm) due to gold nanoparticles and observed in gold nanoparticles consisting solely of gold as a component. The disappearance of this absorption peak of surface plasmons was not observed in combinations of gold and a metal oxide component other than nickel oxide, for example chromium oxide, manganese oxide, iron oxide, cobalt oxide, copper oxide or zinc oxide, the combinations with which were not observed to produce influence on the reaction. The disappearance of this absorption peak of surface plasmons is believed to be the result of mixing of electronic states at the interface between oxidized nickel and gold, or, in other words, hybridization of two types of metal-chemical components.

The conversion to highly oxidized nickel oxide can be observed by the color change in the catalyst and by spectroscopy in the UV and visible spectral regions. As a result of adding gold to nickel oxide, the color of nickel oxide changes from grayish green to brown, and the UV spectrum shows absorption over almost the entire visible region of the spectrum. The UV spectrum and color of the catalyst are similar to the spectrum and color of highly oxidized nickel peroxide (NiO ₂ ) used as a comparative sample. Based on this conclusion, it is believed that nickel oxide is converted to highly oxidized nickel oxide by the addition of gold.

Based on these results, it is believed that the structure of the composite nanoparticles is such that the gold nanoparticles are located in the core, the surface of the gold nanoparticles is coated with highly oxidized nickel oxide, and gold atoms are not present on the surface of the composite nanoparticles.

Intended Operation

The following is an explanation of the intended principle of operation of the catalysts in accordance with this embodiment using an example of the modification and improvement of nickel compounds for which studies have been conducted regarding their use as catalysts and electronic materials.

Examples of the use of heterogeneous nickel compounds for oxidative reactions in accordance with the prior art may include (1) a method of oxidizing alcohol using nickel peroxide (NiO ₂ ) as a stoichiometric oxidizing agent (J. Org. Chem. 27 (1962) 1597), (2 ) an oxygen-based alcohol oxidation reaction using Ni-Al hydrotalcite as a catalyst (Angew. Chem. Int. Ed. 40 (2001) 763), (3) an oxygen-based alcohol oxidation reaction using Mg-Al hydrotalcite containing Ni (II), as a catalyst (J. Mol. Catal. A 236 (2005) 206), (4) a reaction oxidation of oxygen based alcohol using nickel peroxide (NiO ₂ ) nanoparticles as a catalyst (Appl. Catal. A 290 (2005) 25) and the like.

Although highly oxidized nickel peroxide has a higher oxidizing ability than regular nickel oxide, it has long been known that it is able to oxidize various alcohols in a stoichiometric manner, as a result of various modifications and improvements of nickel catalysts, catalytic oxidation of alcohol with molecular oxygen was carried out in the past years. Nickel-containing hydrotalcite catalysts enable nickel to function as oxygen activation sites by combining nickel and another metal element (such as Al or Mg), and this is believed to result in the formation of a peroxide component as a reaction component on nickel. In addition, it has been reported that in processes using nickel peroxide nanoparticles, reactions proceed catalytically as a result of the formation of nickel peroxide in the form of nanoparticles.

Nickel oxide is used as an electrochromic material, for example, in the field of materials for electronic equipment, other than catalysts. In order to increase the reaction rate of nickel oxide films during photoabsorption, we studied (5) films of the chemical compound NiO-Me (where Me is Au, Ag, Cu, Ni, Pd, or Pt) in which the metal (Me) is doped with nickel oxide (J. Phys. D: Appl. Phys. 36 (2003) 2386). Nickel oxide doped metals act as a hole material, and the oxidation staining rate is believed to increase when nickel oxide is converted to highly oxidized nickel oxide.

Such examples of the use of nickel compounds provide important guidance in understanding the manifestation of the catalytic ability exhibited by the catalyst of this embodiment. Although the inventors of the present invention found that nickel peroxide is active in the synthesis of carboxylic acid ester synthesis, the level of activity of the catalyst was low. Pure nickel peroxide and its anhydrides have yet to be obtained, in this respect there are many aspects of their structure that remain unclear, and it is also regarded as a form of nickel oxide (divalent) that has adsorbed oxygen. However, since nickel peroxide is widely used as a stoichiometric oxidation agent, if catalytically active oxidizing active component could be formed due to the use of molecular oxygen for the oxidizing agent, nickel peroxide could be applicable for the oxidation of organic substrates with molecular oxygen. Innovative studies in this area were described in (2) above, and these studies led for the first time in the world to carry out oxygen oxidation using a heterogeneous nickel catalyst realized by highly efficient activation of molecular oxygen by combining nickel and another metal element. In addition, as described in (4) above, the report that nickel peroxide functions as a catalyst by conversion to nanoparticles indicates the importance of controlling the geometric structure for the catalytically active component.

In addition, examples of a method for controlling the oxidized state of nickel oxide used as an electrochromic material may include combining a metal of group 8 and a metal of group 1B, as described in (5) above, thereby increasing the degree of conversion to highly oxidized nickel oxide. This suggests that, also in catalytic reactions, the regulation of the electronic state of oxidized nickel is possible by combining with a specific metal, and this also applies to the basic concept of the catalyst in this embodiment.

As described above, it is assumed that the structure of the composite nanoparticles of this embodiment contains particles X serving as a core, the surface of which is coated with highly oxidized nickel oxide. Based on (1) - (5) above, in the composite nanoparticles of this embodiment, since oxidized nickel and X interact at the atomic level, the electronic state of nickel oxide is converted to a highly oxidized state, and changes in the geometric structure of its active sites, as well as changes in electronic properties can be considered as factors affecting its catalytic effect. In addition, it is assumed that, through the mediation of oxygen atoms, a new active component is formed at the interface between nickel oxide and X, and this is believed to lead to the formation of a new catalyst functionality that is completely different from that which occurs when each of components separately.

Namely, the catalyst for producing the carboxylic acid ester according to this embodiment is clearly different from conventional metal catalysts consisting of a single metal component, binary metal catalysts such as alloys or intermetallic compounds, and binary catalysts consisting of combinations of metal oxides , other than nickel, and metal elements, and is believed to change the state of the active sites, specifically due to the combination of oxidized th nickel and X, leads to completely new characteristics of the catalyst which can not be obtained in the case of catalysts in accordance with the prior art.

Detailed Description of the Carboxylic Acid Ester Catalyst

The catalyst for preparing the carboxylic acid ester according to this embodiment is a catalyst in which oxidized nickel and X (where X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) deposited on the carrier in the range of the atomic ratio Ni / (Ni + X) from 0.20 to 0.99.

The catalyst in accordance with this embodiment preferably further comprises composite nanoparticles consisting of oxidized nickel and X (where X is at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) .

Oxidized nickel and X are preferably deposited on a support in a finely divided state. Oxidized nickel and X are more preferably deposited when dispersed in the form of thin particles or a thin film, and the average diameter of each particle is preferably from 2 to 15 nm, more preferably from 2 to 10 nm, and even more preferably from 2 to 6 nm. Moreover, the average particle diameter, as referred to in this embodiment, refers to the number average particle diameter when measured by a transmission electron microscope (TEM).

The applied composition of nickel and X is such that the atomic ratio of Ni / (Ni + X) is in the range of 0.20 to 0.99, preferably in the range of 0.30 to 0.90, and more preferably in the range of 0.50 to 0.90. The atomic ratio Ni / (Ni + X), as referred to herein, is the ratio of the number of nickel atoms supported on the carrier to the total number of nickel atoms and X atoms. If the atomic ratio Ni / (Ni + X) is in within the above ranges, a certain structure of the active component, composed of nickel and X, and an oxidized state of nickel suitable for the reaction are formed, as a result of which the activity and selectivity tend to be higher than for catalysts in which this atomic ratio is beyond beyond these intervals.

In the case where composite nanoparticles consisting of oxidized nickel and X are contained in the catalyst, this catalyst is not limited to its type in which the nanoparticles are only supported on the carrier, but also includes catalysts in which, in addition to the composite nanoparticles, the separately supported oxidized nickel.

A composite nanoparticle refers to a nanoparticle containing oxidized nickel and X (where X is at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver, and copper).

Although there are no particular restrictions on the structure of composite nanoparticles that contain both components, preferably both components are present in the nanoparticles, and the structure is preferably a phase structure, such as a solid solution structure in which the crystalline positions are randomly occupied by chemical components, the core-shell structure in which each chemical component is separated in the form of concentric spheres, an anisotropic phase structure in which the phases are separated by anisotro nym manner and structure with heterophile bonds, in which both chemical components are present adjacent to each other on the particle surface. More preferably, X serves as a core, and oxidized nickel covers its surface. There are no particular restrictions on the shape of the composite nanoparticles, provided that they contain both components and can be of any shape, such as spheres or hemispheres.

The content of nickel and X in the composite nanoparticles is such that the atomic ratio of Ni / X is preferably in the range from 0.1 to 10, more preferably in the range from 0.2 to 5.0, and even more preferably in the range from 0.3 to 3.0.

The range of the average particle diameter of the composite nanoparticles is preferably from 2 to 15 nm, more preferably from 2 to 10 nm, and even more preferably from 2 to 6 nm.

In the case where the composite nanoparticles have a shape in which X is in the core and oxidized nickel covers its surface, the average particle diameter X is preferably in the range from 1.5 to 12 nm, more preferably in the range from 2 to 10 nm and even more preferably in the range from 2 to 6 nm, taking into account the balance between the manifestation of activity and stability. The thickness of the surface nickel layer is determined by one or more layers of oxidized nickel molecules and varies in accordance with such factors as the composition of supported nickel and X, the atomic ratio and particle diameter of nickel and X in composite nanoparticles, as well as the method by which the catalyst is obtained. The thickness of the nickel layer, based on oxidized nickel molecules, is preferably from about 1 to 5 layers, and more preferably from about 1 to 3 layers. In addition, a complex oxide can be formed inside composite nanoparticles that have a chemically bonded component, such as Ni-O-X, at the interface at which nickel and X components are in contact.

The reason for the existence of preferred intervals for the composition of the deposited nickel and X composition and the atomic ratio of nickel to X in composite nanoparticles and the reason for the tolerance is that the proportion of surface atoms varies according to the particle diameter X. For example, citing gold as an example, when the particle diameter 10 nm gold, the total number of atoms is approximately 2.1 × 10 ⁴ , and the fraction of the number of surface atoms becomes approximately 15%. If the particle diameter is 2 nm, then the total number of atoms is approximately 150, and the fraction of the number of surface atoms becomes approximately 63%. Thus, if we take into account how the surface of X is coated with nickel, we can easily assume that the atomic ratio of nickel to X differs depending on the particle diameter of X.

As described previously, the use of a transmission electron microscope / scanning transmission electron microscope (TEM / STEM) is an effective analytical method for studying the morphology of composite nanoparticles, and images of nanoparticles obtained by TEM / STEM when irradiated with an electron beam make it possible to analyze elements inside the nanoparticles and extract information about the distribution of these elements. As will be indicated in the examples described below, it was confirmed that the composite nanoparticles in accordance with this embodiment have a structure in which nickel and X are contained in all particles, and surface X is coated with nickel. In the case of such a structure, the atomic ratio of nickel to X differs according to the place of analysis of the composition in the nanoparticles, and higher amounts of nickel are found at the edges of the particles compared to the center of the particles. Therefore, a tolerance is provided for the atomic ratio of nickel to X, depending on the location of the analysis site, even for individual nanoparticles, and the interval of this tolerance is included in the intervals of the atomic ratio Ni / X, as described previously.

If you select gold, silver or copper as X, UV and visible spectroscopy (UV-Vis) is an effective means of identifying their structure. In the case of nanoparticles containing only gold, silver or copper, the photoelectric field in the band of visible light and near IR binds to free electrons on the metal surface, which leads to the absorption of surface plasmons. For example, if a catalyst coated with gold nanoparticles is irradiated with visible light, then an absorption spectrum due to plasmon resonance created by gold nanoparticles at a wavelength of about 530 nm is observed. However, in the case of the catalyst coated with nickel oxide and gold in accordance with this embodiment, the absorption of their surface plasmons disappears, which suggests the absence of gold on the surface of the catalyst in accordance with this embodiment.

Preferred examples of oxidized nickel may include nickel oxides formed by the bonding of nickel and oxygen (e.g., Ni ₂ O, NiO, NiO ₂ , Ni ₃ O ₄ or Ni ₂ O ₃ ), and complex oxides containing nickel, such as nickel oxide compounds, are solid solutions or mixtures thereof, and formed by the bonding of nickel and X and / or one or more types of other metal elements and oxygen.

There are no particular restrictions on the solid form of nickel, provided that it allows you to obtain the specified activity of the catalyst, and preferably nickel is in an amorphous state in which there are no diffraction peaks observed by x-ray diffraction. As a result of using this form, since the interaction with oxygen is supposed to be larger and the interface between the mutually bonded oxidized nickel and X increases, an even higher catalyst activity can be obtained.

X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper, and more preferably selected from the group consisting of nickel, palladium, ruthenium, gold and silver.

Although, by its chemical state, X may be a metal, oxide, hydroxide, a complex compound containing X and nickel or one or more kinds of other metal elements, or any mixture thereof, the preferred chemical state is metal or oxide, and metal is more preferred. In addition, there are no particular restrictions on the solid form X, provided that it allows you to get the specified activity of the catalyst, and it can be crystalline or amorphous.

Another metal element, as referred to herein, means a constituent element of the carrier described below, a third constituent element contained in the catalyst in addition to oxidized nickel and X, or a metal component such as an alkali metal, alkaline earth metal or rare earth metal.

The catalyst in accordance with this embodiment contains oxidized nickel and X supported on a support as previously described, and preferably exhibits an excellent effect due to the formation of composite nanoparticles consisting of oxidized nickel and X. In addition, the composite nanoparticle, as referred to in This embodiment relates to a nanoscale particle containing various binary metal components within a single particle. Although examples of various binary metal components may include binary metal particles in which both the nickel component and component X are metals, and metal particles in which an alloy or intermetallic compound of nickel and X is formed, if used as catalysts to obtain a complex carboxylic acid ester, selectivity and catalytic activity of the target product are low compared to the catalyst in accordance with this invention, which makes them suitable yaschimi.

The catalyst in accordance with this embodiment preferably contains oxidized nickel on a support in an independent manner, in addition to composite nanoparticles consisting of oxidized nickel and X. The presence of oxidized nickel not combined with X serves to further increase the structural stability of the catalyst particles and also inhibits an increase in pore diameter caused by prolonged reactions, and the concomitant growth of composite nanoparticles. This effect is noticeable when an aluminum-containing composition based on silica containing silica and aluminum or a composition containing silica, alumina and magnesium oxide is used for the carrier, as will be described below.

Below is an explanation of the action, as a result of which the structural stability of the catalyst particles is increased, and the increase in pore diameter caused by prolonged reactions, with the concomitant growth of composite nanoparticles, is restrained due to the presence of free oxidized nickel on the support.

As will be described later, the formation of acetals and the like. under the influence of acidic substances, examples of which are methacrylic acid or acrylic acid, which are by-products typical of reactions for the production of esters of carboxylic acids, can be restrained by maintaining the pH of the reaction system in the range from 6 to 9, and more preferably under neutral conditions (for example, at a pH of 6.5 to 7.5) or, in other words, maintaining the pH as close as possible to pH 7 by adding an alkali metal or alkaline earth metal compound to the reaction system.

According to studies conducted by the inventors of the present invention, in the case of a long-term reaction in accordance with the procedure described above using a catalyst in which single-component gold nanoparticles are supported on a support according to this embodiment, it was found that the catalyst particles undergo structural changes gradually. This phenomenon is believed to be due to the fact that the catalyst particles are repeatedly locally exposed to acid and base due to the reaction procedure described above, as a result of which a portion of Al in the support dissolves and precipitates, resulting in a rearrangement of the cross-linked structure based on silicon oxide and alumina, which, in turn, causes an increase in the pore diameter of the catalyst particles. In addition, at the same time as the pore diameter increases, particle growth is stimulated by sintering of gold particles, which has been found to reduce the activity of the catalyst.

On the other hand, the presence of composite nanoparticles and oxidized nickel separately on the support serves to increase the structural stability of the catalyst particles due to the procedure described above, while also increasing the pore diameter and the growth of composite nanoparticles. As described previously, the reason for this is believed to be that the reaction between oxidized nickel and the constituent elements of the support leads to the formation of nickel oxide compounds or complex nickel-containing oxides, such as solid solutions, and as a result of such compounds act stabilizingly on the cross-linked structure based on silicon oxide and aluminum oxide, the structural stability of the catalyst particles is significantly increased. The performance of such a catalyst with structural stabilization effects, as the authors of this invention suggest, is due to the oxidized nickel present in the carrier. Therefore, these effects occur naturally in the case when the oxidized nickel contained in the composite nanoparticles is in contact with the carrier, and the maximum stabilizing effects are believed to be achieved if free oxidized nickel is present on the carrier.

Carrier

With respect to the catalyst support for producing the carboxylic acid ester according to this embodiment, there are no particular restrictions, provided that it is capable of supporting oxidized nickel and X, and the catalyst support according to the prior art can be used to synthesize the carboxylic acid ester .

Examples of this carrier may include various types of carriers, such as activated carbon, silica, alumina, silica-alumina, titanium dioxide, silica-titania, zirconia, magnesium oxide, silica-magnesium oxide system, silica-alumina-magnesium oxide, calcium carbonate, zinc oxide, zeolite and crystalline metal silicate system. Preferred examples thereof may include activated carbon, silica, alumina, silica-alumina, silica-alumina, silica-alumina-magnesia, titania, silica-titania and zirconia . More preferred examples may include a silica-alumina system and a silica-alumina-magnesium oxide system.

In addition, the carrier may also contain one or more types of metal components selected from the group consisting of alkali metals (Li, Na, K, Rb, Cs), alkaline earth metals (Be, Mg, Ca, Sr, Ba) and rare earths metals (La, Ce, Pr). The supported metal component is preferably an oxide obtained by calcining, for example, nitrate or acetate.

Preferably, a silica-based composition comprising silica and aluminum or a composition comprising silica, alumina and magnesium oxide is used for the carrier. This type of carrier has a higher water resistance compared to silica and a higher acid resistance compared to alumina. In addition, it also provides superior physical properties compared to carriers commonly used in accordance with the prior art, including greater hardness and higher mechanical strength than activated carbon, while it also provides more stable deposition of oxidized nickel and X, which are the active components of the catalyst (where X is at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver, and copper). As a result, the catalyst is able to maintain a high level of reactivity over a long period of time.

A catalyst for producing a carboxylic acid ester in which oxidized nickel and X have a specific atomic ratio and an aluminum-containing silica composition or a composition containing silica, alumina and magnesium oxide are used for a carrier that exhibits high mechanical strength and physical stability, having a large surface area suitable for use as a catalyst carrier, also exhibits sufficient corrosion resistance with respect to the nature liquid phase reaction in the form of a synthesis reaction of a carboxylic acid ester in the presence of oxygen.

The following is an explanation of the properties of the support of this embodiment, which provides a significant increase in catalyst life. The reason that a significant increase in the mechanical strength and chemical resistance of the carrier is possible is, as suggested, the following.

In a silica-based aluminum support, Si-O-Al-O-Si bonds are re-formed by adding aluminum (Al) to the non-crosslinked silica (Si-O) chains in silica gel. Since Al crosslinked structures are formed without losing the stability inherent to Si-O chains with respect to acidic substances, Si-O bonds are strengthened and hydrolysis resistance (referred to hereinafter as "water resistance") is believed to be while significantly increasing. In addition, when cross-linked Si-O-Al-O-Si structures are formed, the number of non-cross-linked Si-O chains decreases individually compared to silica gel, which is also believed to lead to an increase in mechanical strength. Namely, it is assumed that the number of formed Si-O-Al-O-Si structures is related to an increase in the mechanical strength and water resistance of the obtained silica gel.

In a carrier based on a silica-alumina-magnesium oxide system, due to the presence of magnesium oxide in addition to silica and alumina, charge stabilization is maintained as a result of compensating neutralization by Mg (divalent) charge differences due to differences in valency between Si ( tetravalent) and Al (trivalent), which are caused by the formation of cross-linked structures of Si-O-Al-O-Si. Moreover, since the charge balance is achieved through the use of a three-component system, it is assumed that the structural stability is further enhanced. Therefore, in contrast to a carrier based solely on a silica-alumina system exhibiting acidity, a carrier containing silica, alumina and magnesium oxide is almost neutral, and this is believed to inhibit appreciable formation of acetal under acidic conditions.

One of the reasons for the possibility of stable support of oxidized nickel and X on the carrier over a long period of time is that the mechanical strength and chemical resistance of the carrier are significantly improved as described above, thereby providing a carrier with superior physical properties compared to commonly used carriers in accordance with the prior art. As a result, nickel and X, which are active components of the catalyst, are resistant to peeling, which, accordingly, provides the possibility of their stable support on the carrier for a long period of time.

It has been found that the nickel component of commonly used carriers, such as silica or a silica-alumina system, is gradually washed away during lengthy reactions. In contrast, in the case of using the above media, the authors of the present invention found that the leaching of the Nickel component is restrained for a long period of time. Based on the results of X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM / EDX), and high-resolution X-ray luminescence (HRXRF), in the case of using a carrier based on silicon oxide or based on a silicon oxide-titanium dioxide system, it was confirmed that the leachable nickel the component is nickel oxide present separately on the carrier. Since nickel oxide is an acid soluble compound, it is believed that it is washed away by typical by-products of this reaction in the form of acidic substances represented by methacrylic acid and acrylic acid.

Based on the analysis of the chemical state of nickel by high resolution X-ray luminescence (HRXRF), the nickel catalyst, in accordance with this embodiment, is supposed to be not only nickel oxide, which is the only compound, but is also present as a result of the formation of complex oxides containing nickel such as nickel oxide compounds, solid solutions, or mixtures thereof, formed by the bonding of nickel and a constituent element of the carrier.

High resolution X-ray luminescence (HRXRF) analysis makes it possible to analyze the chemical state based on the energy positions (chemical shifts) and the shape of the resulting spectrum due to its extremely high energy resolution. In particular, in the case of the K spectra of 3d transition metal elements, changes occur in the chemical shift and shape due to changes in the valence and electronic state, and the chemical state can be analyzed in detail. In the catalyst in accordance with this embodiment, changes occurred in the Ni K spectrum, thereby confirming that the chemical state of nickel is different from nickel oxide, which is the only compound.

For example, nickel aluminate, which is formed from nickel oxide and alumina, is a compound that is insoluble in acid. As a result of the formation of such a nickel compound on the support, the leaching of the nickel component is expected to be substantially reduced.

The following is an explanation of two preferred supports for significantly increasing the life of the catalyst in accordance with this embodiment, namely a support containing silica and alumina and a support based on a silica-alumina-magnesium oxide system.

The elemental composition of the carrier containing silica and alumina is such that the amount of aluminum is from 1 to 30 mol%, preferably from 5 to 30 mol%, and more preferably from 5 to 25 mol%, based on the total molar amount of silicon and aluminum. If the amount of aluminum is within this range, acid resistance and mechanical strength tend to correspond to suitable values.

Furthermore, in addition to silica and alumina, the additional inclusion of at least one type of basic metal component selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals, in the catalyst carrier in accordance with this embodiment is preferred from the point of view additional increase in mechanical strength and chemical resistance. Examples of alkali metals of this basic metal component may include Li, Na, K, Rb and Cs, examples of alkaline earth metals may include Be, Mg, Ca, Sr and Ba, and examples of rare earth metals may include La, Ce and Pr.

The elemental composition of the carrier containing silica, alumina and at least one type of main metal component selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals, is such that the amount of aluminum is in the range from 1 to 30 mol. %, preferably from 5 to 30 mol.% and more preferably from 5 to 25 mol.%, based on the total molar amount of silicon and aluminum. In addition, the ratio of the main metal component to alumina, based on the atomic ratio (alkali metal + 1/2 × alkaline earth metal + 1/3 × rare earth metal) / Al, is preferably in the range from 0.5 to 10, more preferably from 0.5 to 5.0, and even more preferably from 0.5 to 2.0. If the elemental composition of silicon oxide, alumina and the main metal component is in the above range, then silicon, aluminum and the main metal element form a certain stably connected structure, and as a result, the mechanical strength and water resistance of the carrier tend to correspond to suitable values.

Moreover, a carrier comprising silica, alumina and magnesium oxide preferably comprises from 42 to 90 mol% of silicon, from 5.5 to 38 mol% of aluminum and from 4 to 38 mol% of magnesium, and more preferably from 75 to 90 mol% of silicon, from 5.5 to 15 mol% of aluminum oxide and from 4 to 10 mol% of magnesium oxide, based on the total molar amount of silicon, aluminum and magnesium, in terms of mechanical strength and water resistance of the carrier . This is believed to be due to the fact that silicon, aluminum and magnesium, when contained in these intervals, form a certain stably bound structure.

The following description provides an explanation of the method for producing two preferred types of carriers used in this embodiment and having the composition described above.

There are no particular restrictions on the method for producing a carrier containing silica and alumina, and an aluminum-containing silica composition obtained, for example, in accordance with methods 1) to (5) below, can be obtained by calcination under the conditions described below.

(1) Use of a commercially available silica-alumina composition.

(2) Reaction of a silica sol with a solution of an aluminum compound.

(3) Reaction of a silica sol with a water-insoluble aluminum compound.

(4) Reaction of silica gel with an aqueous solution of an aluminum compound soluble in water.

(5) Solid-phase interaction of silica gel with an aluminum compound.

The following description provides a detailed explanation of the methods for preparing the carrier indicated in (2) to (5) above.

In methods (2) through (5) above, a silica sol or silica gel is used as a source of silica. There are no particular restrictions on the length of the Si-O chain of silica gel, provided that it has Si sites that do not have cross bonds that react with Al. Although preferred examples of aluminum compounds may include water-soluble compounds such as sodium aluminate, aluminum chloride hexahydrate, aluminum perchlorate hexahydrate, aluminum sulfate, aluminum nitrate nonahydrate or aluminum diacetate, insoluble compounds such as aluminum hydroxide or aluminum oxide can also be used when provided that they are compounds that react with cross-linked Si in a silica sol or silica gel.

In the case of using methods (2) and (3), in which a silica sol is used as a starting material, a silica sol is mixed with an aluminum compound to obtain a mixed sol containing a silica sol and an aluminum compound, after which a hydrothermal reaction is carried out for from 1 to 48 hours at a temperature of from 20 to 100 ° C and drying to obtain a gel, and then fired at temperature, time and atmospheric conditions, which are described below. Alternatively, an alkaline aqueous solution is added to the above mixed sol to co-precipitate silica and an aluminum compound, followed by drying and subsequent calcination under the conditions described below. In addition, the above mixed sol can be converted to fine particles by direct use of a spray drying apparatus, or the mixed sol can be dried to form a gel, then granulated to obtain a carrier containing silica and aluminum and having particles of the desired diameters.

In the case of method (3), in particular, although the silica sol interacts with an aluminum compound that is insoluble in water, the aluminum compound can be pre-ground to obtain particles of a given size or pre-coarsely ground. After mixing and reacting the silica sol and the water-insoluble aluminum compound, the mixture is dried, followed by firing under the conditions described below. The silica-alumina composition can be ground to obtain particles of a predetermined size after calcination without first grinding the aluminum compound.

In the case of method (4), in which silica gel is used as a starting material, an aqueous solution of a water-soluble aluminum compound is reacted in silica gel, and the silica gel can either be pre-ground to obtain particles of a given size or pre-coarsely ground. After mixing and reacting silica gel and an aqueous solution of a water-soluble aluminum compound for 1 to 48 hours, at a temperature of 20 to 100 ° C, the mixture is dried, followed by calcination for 1 to 48 hours under the conditions described below. The composition of silicon oxide-alumina can be crushed to obtain particles of a given size after firing without preliminary grinding silica gel.

Similarly, in method (5), which also uses silica gel as a starting material, the mixture is obtained by reacting silica gel with an aluminum compound in a solid phase. Al interacts in the solid phase with Si, which has no transverse bonds. Silica gel and aluminum compound can be pre-crushed to obtain particles of a given size or can be pre-coarsely ground. Grinding can be performed separately for each substance or both substances can be crushed after mixing. Firing is carried out at temperature, time and atmospheric conditions, which are described below. A mixture of silica gel and aluminum compound can be used in grinding to the desired particle size after the reaction without prior grinding.

With regard to a method for producing a carrier containing silica, alumina and at least one type of main metal component selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals, the carrier can be obtained by drying a suspension containing a mixture of silicon oxide, alumina and an alkali metal compound, an alkaline earth metal compound and / or a rare earth metal compound, in accordance with a method for producing a carrier comprising silica and ksid alumina as described above, followed by firing under conditions to be described later.

Typical commercially available compounds, similar to the aluminum-containing starting material, can be used as the starting compound of an alkali metal, alkaline earth metal, and rare earth metal. The starting material is preferably a water-soluble compound and more preferably is a hydroxide, carbonate, sulfate or acetate.

Another example of a preparation method that can be used may include adsorption of a base metal component selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals, on a carrier containing silica and alumina. For example, an immersion method can be used in which the carrier is added to a solution in which the base metal compound is dissolved, followed by heat treatment, or an impregnation method in which the main compound in an amount equal to the pore volume is included in the carrier, after which drying follows. However, the method in which the alkali metal compound is then adsorbed requires caution in that the drying of the liquid is carried out under mild conditions, taking into account the high degree of dispersion of the main metal component on the carrier.

The following is an explanation of a method for producing a carrier comprising silica, alumina, and magnesium oxide. A carrier based on a silica-alumina-magnesia system obtained in accordance with methods (1) to (5) below can, for example, be obtained by calcination under the conditions described below.

(1) Pre-gelation of silica-alumina followed by the addition of magnesium oxide.

(2) Reaction of a silica sol, an aluminum compound, and a magnesium compound.

(3) The interaction of a silica sol, a water-insoluble aluminum compound, and a water-insoluble magnesium compound.

(4) The interaction of silica gel, a water-soluble aluminum compound and a water-soluble magnesium compound.

(5) Solid-phase interaction of silica gel, aluminum compound and magnesium compound.

In methods (1) to (5) above, a silica sol, water glass, or silica gel is used as a source of silica. There are no particular restrictions on the length of the Si-O chain of silica gel, provided that it has Si sites that do not have cross bonds that react with Al. Although preferred examples of aluminum compounds may include water-soluble compounds such as sodium aluminate, aluminum chloride hexahydrate, aluminum perchlorate hexahydrate, aluminum sulfate, aluminum nitrate nonahydrate or aluminum diacetate, insoluble compounds such as aluminum hydroxide or aluminum oxide can also be used when provided that they are compounds that react with cross-linked Si in a silica sol or silica gel. Examples of magnesium compounds that can be used may include magnesium oxide, magnesium hydroxide, magnesium acetate, magnesium nitrate, magnesium chloride and magnesium sulfate.

In the case of method (1), in which a silica-alumina gel is used as a starting material, sulfuric acid is initially added to the liquid glass to obtain a silica hydrogel having a pH of from 8 to 10.5, followed by the addition of a solution to it Al ₂ (SO ₄ ) ₃ (pH 2 or less) and the addition of sodium aluminate (pH 5 to 5.5) to obtain a silica-alumina hydrogel. After that, the moisture content in the gel is adjusted to a value of from 10 to 40% by spray drying, etc., followed by the addition of magnesium oxide, carrying out a hydrothermal reaction for 1 to 5 hours at a temperature of from 50 to 90 ° C, drying and then firing under the conditions described below to obtain a carrier.

In the case of methods (2) and (3) in which a silica sol is used as a starting material, a silica sol, an aluminum compound and a magnesium compound are mixed to obtain a mixed sol containing a silica sol, an aluminum compound and a magnesium compound, and hydrothermal reaction for 1 to 48 hours at a temperature of from 20 to 100 ° C and subsequent drying to obtain a gel, after which the gel is fired at temperature, time and atmospheric conditions, which are described below. Alternatively, an alkaline aqueous solution is added to the above mixed sol to co-precipitate silica, an aluminum compound and a magnesium compound, followed by drying and subsequent calcination under the conditions described below. In addition, the above mixed sol can be converted to fine particles by direct use of a spray drying apparatus, or the mixed sol can be dried to form a gel and then granulated to obtain a carrier containing silica, alumina and magnesium oxide and having particles of desired diameters.

In the case of method (3), in particular, although the silica sol interacts with an aluminum compound and a magnesium compound that are insoluble in water, the aluminum compound and magnesium compound can be pre-crushed to obtain particles of a given size or pre-coarsely ground. After mixing and reacting a silica sol, a water-insoluble aluminum compound, and a water-insoluble magnesium compound, the mixture is dried, followed by firing under the conditions described below. The composition of silicon oxide-alumina-magnesium oxide can be crushed to obtain particles of a given size after firing without preliminary grinding the aluminum compound and magnesium compound.

In the method (4) using silica gel as a starting material, an aqueous solution of a water-soluble aluminum compound and a water-soluble magnesium compound is reacted in silica gel, and the silica gel can either be pre-crushed to obtain particles of a given size, or pre-coarsely ground. After mixing and reacting silica gel and an aqueous solution of a water-soluble aluminum compound and a water-soluble magnesium compound for 1 to 48 hours, at a temperature of 20 to 100 ° C, the mixture is dried, followed by calcination for 1 to 48 hours under the conditions described below . The composition of silicon oxide-alumina-magnesium oxide can be crushed to obtain particles of a given size after firing without preliminary grinding silica gel.

Similarly, in method (5), which also uses silica gel as a starting material, the mixture is obtained by reacting silica gel with an aluminum compound and a magnesium compound in the solid phase. Silica gel, aluminum compound and magnesium compound can be pre-crushed to obtain particles of a given size or can be pre-coarsely ground. Grinding can be performed separately for each substance or all three substances can be crushed after mixing. Firing is performed at temperature, time and atmospheric conditions, which are described below. A mixture of silica gel, aluminum compound and magnesium compound can be used to grind to the desired particle size after the reaction without prior grinding.

In addition, inorganic and organic substances can be added to the mixed suspension of each of the above starting materials in order to control the properties of the suspension or finely control the properties of the product, for example, the structure of the pores, or the properties of the resulting carrier.

Specific examples of inorganic substances used may include inorganic acids such as nitric acid, hydrochloric acid or sulfuric acid, metal salts of alkali metals such as Li, Na, K, Rb or Cs, or alkaline earth metals such as Mg, Ca, Sr or Ba, water-soluble compounds, such as ammonia or ammonium sulfate, and clay minerals, which form suspensions by dispersion in water. In addition, specific examples of organic substances may include polymers such as polyethylene glycol, methyl cellulose, polyvinyl alcohol, polyacrylic acid or polyacrylamide.

Although there are various effects when adding inorganic and organic substances, these effects can mainly include the formation of a spherical carrier, as well as the regulation of pore diameter and pore volume, and more specifically, the properties of the liquid with respect to the mixed suspension are an important factor in obtaining a spherical carrier. The properties of the liquid can be changed to values that facilitate the production of a spherical support by controlling the viscosity and concentration of solid particles using inorganic and organic substances. In addition, the regulation of pore diameter and pore volume can be performed by selecting the optimal organic compound that remains inside the carrier at the stage of formation and can be removed by firing and washing after formation.

The carrier can be obtained by spray drying a mixed suspension of each of the above starting materials and additives. Known atomizing devices, such as rotary disk devices, dual fluid nozzle devices, or pressurized nozzle devices, can be used to grind the mixed suspension to a drip state.

The spray liquid must be used in a well-mixed state. If the liquid is poorly mixed, then the liquid affects the characteristics of the carrier, for example, causes a decrease in durability due to the uneven distribution of the composition. In particular, when compiling a mixture of starting materials, since there are cases in which an increase in the viscosity of the suspension or partial gelation occurs (compaction of the colloid), care should be taken to prevent the formation of inhomogeneous particles. Accordingly, there are cases in which it is preferable to adjust the pH of the silica sol near a value of 2, in a semi-stable range, for example, using a method such as adding acid or base, while also taking other measures, such as gradually mixing the starting materials with stirring.

It is necessary that the sprayed liquid has a certain degree of viscosity and concentration of solid substance. If the viscosity and concentration of a solid are excessively low, many of the porous bodies obtained by spray drying have the appearance of deformed spheres, rather than perfect spheres. In addition, if the viscosity and concentration of a solid substance are excessively high, then, in addition to a negative effect on the dispersion of porous bodies, depending on the properties of the liquid, stable drops cannot be formed. Therefore, the viscosity is preferably in the range of 5 to 10,000 cP, provided that the liquid can be sprayed at this viscosity, and a higher viscosity allowing spraying is preferable in terms of shaping, and taking into account the balance between viscosity and ease of handling viscosity preferably selected from the range of 10 to 1000 cP. In addition, a concentration of a solid in the range of 10 to 50 wt.% Is preferred in terms of particle shape and diameter. In addition, the hot air temperature at the inlet of the drying column of the spray drying apparatus from 200 to 280 ° C and the outlet temperature of the drying column in the range from 110 to 140 ° C are preferred as a common indicator of spray drying conditions.

The firing temperature of the carrier is usually selected in the range from 200 to 800 ° C. Sintering at temperatures above 800 ° C causes a noticeable decrease in the specific surface, which makes this temperature undesirable. In addition, although there are no particular restrictions on the firing atmosphere, firing is usually carried out in air or in a nitrogen atmosphere. In addition, although the firing time can be determined depending on the specific surface after firing, it usually ranges from 1 to 48 hours. Due to changes in the physical properties of the carrier, such as porosity, it is necessary to select suitable temperature and heating conditions as firing conditions. If the calcination temperature is excessively low, it is difficult to maintain the durability in the form of a complex oxide, while if the calcination temperature is excessively high, this leads to a decrease in pore volume. In addition, the heating conditions may preferably include a gradual increase in temperature by programmed heating and the like. In the case of firing under such conditions, when the temperature rises rapidly, gasification and combustion of inorganic and organic substances become intense, causing them to be exposed to temperatures above a given temperature or to cause grinding, which makes such conditions undesirable.

The specific surface area of the carrier, when measured by the BET nitrogen adsorption method, is preferably 10 m ² / g or more, more preferably 20 m ² / g or more, and even more preferably 50 m ² / g or more, from the point of view of ease of deposition of composite nanoparticles , catalytic activity and resistance to peeling. In addition, although this is not particularly required in terms of catalytic activity, the specific surface area of the carrier is preferably 700 m ² / g or less, more preferably 350 m ² / g or less, and even more preferably 300 m ² / g or less, s point of view of mechanical strength and durability.

The pore structure of the carrier is an extremely important physical property with respect to the deposition characteristics of metal components, with the exception of strength, long-term stability, including peeling resistance, and reaction characteristics, and the pore diameter is the physical quantity required to exhibit these characteristics. If the pore diameter is less than 3 nm, then, although the peeling characteristics of the supported metal are suitable, in the case of using a catalyst for a liquid-phase reaction and the like. the pore diameter is preferably 3 nm or more, from the point of view of maintaining high reactivity without excessively large diffusion resistance within the pores, so that the diffusion step of the starting reaction materials is not a limiting step. On the other hand, the pore diameter is preferably 50 nm or less, from the point of view of resistance of the catalyst to cracking and resistance to peeling of the deposited metal. Thus, the pore diameter is preferably from 3 to 50 nm, and more preferably from 3 to 30 nm. Pore volume is required to provide pores for applying composite nanoparticles. However, if the pore volume becomes excessively large, then the strength tends to decrease rapidly. Therefore, a pore volume in the range of 0.1 to 1.0 ml / g is preferable, while from a strength point of view, a value in the range of 0.1 to 0.5 ml / g is more preferable. The carrier of this embodiment preferably satisfies the above ranges for pore diameter and pore volume.

The shape of the carrier is selected from a hollow cylindrical shape or a cellular shape, which is a structure that exhibits low pressure loss in the fixed layer, in accordance with the type of reaction, and under conditions of suspension in the liquid phase, the suspension particles are usually spherical, and a carrier shape that allows use the carrier by selecting the optimal pore diameter based on reactivity and separation method. For example, in the case of performing a catalyst separation process using a typical simple precipitation separation method, the particle diameter is preferably selected from 10 to 200 μm, more preferably from 20 to 150 μm and even more preferably from 30 to 150 μm, taking into account the balance with the reaction characteristics . In the case of a cross-filter method, small particles having a diameter of 0.1 to 20 μm or less are preferred due to their high reactivity. The catalyst for producing a carboxylic acid ester in accordance with this embodiment can thus be used to change the appearance and shape of the carrier in accordance with the purpose of use.

Although there are no particular restrictions on the amount of oxidized nickel deposited on the carrier, it is usually from 0.1 to 20 wt.%, Preferably from 0.2 to 10 wt.%, More preferably from 0.2 to 5 wt.% And even more preferably 0.5 to 2 wt.% based on nickel based on the weight of the carrier. The amount of X deposited on the carrier is usually from 0.1 to 10 wt.%, Preferably from 0.2 to 5 wt.%, More preferably from 0.2 to 2 wt.%, Even more preferably from 0.3 to 1.5 wt.% And particularly preferably from 0.5 to 1.0 wt.% Calculated on the metal of the mass of the carrier.

Moreover, in this embodiment, there is a preferred range for the atomic ratio between nickel and the elemental composition of the carrier. In the case of using a carrier of this embodiment containing silica and alumina, the ratio of nickel and alumina in the catalyst, based on the atomic ratio of Ni / Al, is preferably from 0.01 to 1.0, more preferably from 0.02 to 0.8 and even more preferably from 0.04 to 0.6. In addition, in the case of the use of a carrier containing silica, alumina and at least one type of main metal component selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals, the ratio of nickel and alumina in the catalyst, based on the atomic ratio of Ni / Al is preferably from 0.01 to 1.0, more preferably from 0.02 to 0.8, and even more preferably from 0.04 to 0.6, while the ratio of nickel to base metal component per per atomic ratio Ni / (alkali metal + alkaline earth metal + rare earth metal), is preferably from 0.01 to 1.2, more preferably from 0.02 to 1.0, and even more preferably from 0.04 to 0.6.

Moreover, preferred ranges are also available for the atomic ratio between nickel and the constituent elements of the carrier aluminum and magnesium in the case of a carrier based on a system of silicon oxide-alumina-magnesium oxide. The ratio of nickel and alumina in the catalyst, based on the atomic ratio of Ni / Al, is preferably from 0.01 to 1.0, more preferably from 0.02 to 0.8, and even more preferably from 0.04 to 0.6 . In addition, the ratio of nickel and magnesium, based on the atomic ratio of Ni / Mg, is preferably from 0.01 to 1.2, more preferably from 0.02 to 1.0, and even more preferably from 0.04 to 0 , 6.

If the atomic ratio of nickel and aluminum, which are a constituent element of the carrier, the main metal element or magnesium are within the above ranges, then there is a tendency to increase the effects leading to the suppression of leaching of nickel and structural changes in the catalyst particles. This is believed to be the result of the formation of a specific complex oxide of nickel, aluminum, a base metal component and magnesium when they are within these ranges, whereby a stably bonded structure is formed.

The catalyst for producing a carboxylic acid ester according to this embodiment may also contain a third constituent element as an active component of the catalyst, in addition to oxidized nickel and X. Examples of elements that may be contained may include titanium, vanadium, chromium, manganese, iron, cobalt, zinc, gallium, zirconium, niobium, molybdenum, rhodium, cadmium, indium, tin, antimony, tellurium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, mercury, thallium, lead, bismuth, aluminum, boron, silicon and phosphorus. The content of these third constituent elements is from 0.01 to 20 wt.% And preferably from 0.05 to 10 wt.% Calculated on the catalyst. In addition, the catalyst may also contain at least one type of metal component selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals. The content of these alkali metals, alkaline earth metals or rare earth metals is selected in the range of 15 wt.% Or less based on the catalyst.

It should be noted that these third constituent elements or alkali metals, alkaline earth metals and rare earth metals may be contained in the catalyst during the preparation and reaction of the catalyst, or a method may be used in which they are pre-contained in the carrier.

Catalyst form

The specific surface area of the catalyst in accordance with this embodiment, as measured by BET nitrogen adsorption, is preferably in the range from 20 to 350 m ² / g, more preferably from 50 to 300 m ² / g, and even more preferably from 100 to 250 m ² / g, in terms of catalytic activity and resistance to peeling of active components.

The pore structure of the catalyst is an extremely important physical property with respect to the deposition characteristics of metal components, long-term stability, including peeling resistance, and reaction characteristics, and the pore diameter is the physical quantity required to exhibit these characteristics. If the pore diameter is less than 3 nm, then although the peeling characteristics of the supported metal are suitable, in the case of a catalyst for a liquid phase reaction and the like, the pore diameter is preferably 3 nm or more, from the point of view of maintaining high reactivity without excessively high resistance diffusion within the pores, so that the diffusion step of the starting reaction materials is not a limiting step. On the other hand, the pore diameter is preferably 50 nm or less, from the point of view of resistance of the catalyst to cracking and resistance to peeling of the deposited metal. Accordingly, the pore diameter is preferably from 3 to 50 nm, more preferably from 3 to 30 nm, and even more preferably from 3 to 10 nm. The pore volume is preferably in the range from 0.1 to 1.0 ml / g, more preferably from 0.1 to 0.5 ml / g, and even more preferably from 0.1 to 0.3 ml / g, from the point of view application characteristics and reaction characteristics. The catalyst in accordance with this embodiment preferably satisfies the above ranges for pore diameter and pore volume.

The pore diameter of the catalyst may be suitably selected depending on the type of reaction. For example, when used in a suspension state in a liquid phase, the pore diameter varies according to the method used to separate the catalyst, and in the case of separation by spontaneous precipitation, it is preferably from 10 to 200 μm, more preferably from 20 to 150 μm and even more preferably from 20 up to 100 microns.

A method of producing a catalyst used to produce a carboxylic acid ester

There are no particular limitations with respect to the catalyst preparation method in accordance with this embodiment, provided that the catalyst is prepared as described above and commonly used supported catalyst preparation methods can be used, examples of which may include impregnation methods (such as adsorption, filling pore, drying by evaporation of moisture or spraying), precipitation methods (such as co-precipitation, precipitation or stirring), ion exchange and vapor deposition. In this embodiment, impregnation and precipitation methods are preferred, with precipitation methods being more preferred.

The following description provides an explanation of a typical method for producing a catalyst in accordance with this embodiment using an example of deposition. In a first step, for example, a catalyst precursor is prepared by depositing nickel and component X on a support by neutralizing an acidic aqueous solution of a soluble metal salt containing nickel and X. In this step, the components of nickel and X (such as hydroxide) are deposited and supported on the support by a neutralization reaction between nickel and X ions in an aqueous solution. The combination of nickel and component X is preferably made more suitable by simultaneously precipitating both components from a mixed aqueous solution.

Then, in the second stage, the catalyst in accordance with this embodiment can be obtained by washing and drying the catalyst precursor obtained in the first stage, as necessary, followed by heat treatment.

Examples of soluble nickel-containing metal salts that are used to prepare the catalyst may include nickel nitrate, nickel acetate, and nickel chloride. In addition, examples of soluble metal salts containing X may include palladium chloride and palladium acetate when palladium is selected as X, ruthenium chloride and ruthenium nitrate when ruthenium is selected as X, hydrochloric acid, sodium tetrachloroaurate, dicyanoaurate potassium, gold diethylamine trichloride and gold cyanide in the case when gold is selected as X, and silver chloride and silver nitrate in the case when silver is selected as X.

Examples of the bases used to prepare the catalyst may include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and ammonia. In addition, the carrier may also contain one or more kinds of basic metal components selected from the group consisting of alkali metals (such as Li, Na, K, Rb or Cs), alkaline earth metals (such as Be, Mg, Ca, Sr or Ba) and rare earth metals (such as La, Ce or Pr).

In a first step, an acidic aqueous solution of a soluble metal salt containing nickel and X is mixed with a carrier and then neutralized with a base with stirring to precipitate a precipitate of nickel and component X on the carrier. During the deposition of nickel and component X, suitable conditions are selected, such as the concentration of the aqueous solution containing nickel and X, the base, the pH of the aqueous solution and temperature.

The concentration of each component in an aqueous solution containing nickel and X is usually in the range from 0.0001 to 1.0 mol / L, preferably from 0.001 to 0.5 mol / L, and more preferably from 0.005 to 0.2 mol / L . The ratio of nickel and X in the aqueous solution, based on the atomic ratio of Ni / X, is preferably in the range from 0.1 to 10, more preferably from 0.2 to 5.0, and even more preferably from 0.5 to 3.0.

In addition, the pH of the aqueous solution is adjusted with the above base so that the pH is typically in the range of 5 to 10, and preferably in the range of 6 to 8. The temperature of the aqueous solution is usually in the range of 0 to 100 ° C, preferably from 30 to 90 ° C and more preferably from 60 to 90 ° C.

In addition, there are no particular restrictions on the deposition time of nickel and component X, and although this time varies depending on factors such as the components applied, the amounts of nickel and X applied and the ratio of nickel to X, it is usually in the range of 1 minute to 5 hours, preferably from 5 minutes to 3 hours, and more preferably from 5 minutes to 1 hour.

The temperature during the heat treatment of the catalyst precursor in the second stage is usually from 40 to 900 ° C, preferably from 80 to 800 ° C, more preferably from 200 to 700 ° C and even more preferably from 300 to 600 ° C. Heat treatment is carried out in air (or in atmospheric air), in an oxidizing atmosphere (such as oxygen, ozone, nitric oxide, carbon dioxide, hydrogen peroxide, hypochlorous acid or inorganic / organic peroxide) or in an inert gas atmosphere (such as helium, argon or nitrogen). The duration of the heat treatment is suitably selected in accordance with the heat treatment temperature and the amount of catalyst precursor.

Following the aforementioned second stage, if necessary, a reduction treatment in a reducing atmosphere (such as hydrogen, hydrazine, formalin or formic acid) can be carried out. In this case, the reduction is performed by choosing a processing method in which oxidized nickel is not completely reduced to a metallic state. The temperature and duration of the reduction treatment are suitably selected according to the type of reducing agent, type X, and amount of catalyst.

Moreover, if necessary, an oxidative treatment can be carried out in air (or in atmospheric air) or in an oxidizing atmosphere (such as oxygen, ozone, nitric oxide, carbon dioxide, hydrogen peroxide, hypochlorous acid or inorganic / organic peroxide), followed by heat treatment or reduction treatment as described above.

The third constituent, in addition to nickel and X, may be added during the preparation of the catalyst or under reaction conditions. An alkali metal, alkaline earth metal or rare earth metal can also be added in the process of obtaining the catalyst or in the reaction system. In addition, the starting materials of the third constituent element, an alkali metal, an alkaline earth metal, and a rare earth metal are selected from salts of organic acids, salts of inorganic acids, hydroxides, and the like.

Method for producing carboxylic acid ester

The carboxylic acid ester can be obtained from (a) an aldehyde and an alcohol, or (b) one or more types of alcohols in the presence of oxygen using a catalyst to produce a carboxylic ester in accordance with this embodiment.

Although there are no particular restrictions on the amount of catalyst used, it can vary over a wide range in accordance, for example, with the types of starting reaction materials, the composition of the catalyst and the method of preparation thereof, the reaction conditions or the type of reaction in the case of a catalyst in suspension in a reaction state , the catalyst can preferably be used so that the concentration of solid substance in the suspension is in the range from 1 to 50 wt./vol.%, preferably from 3 to 30 w / v% and more preferably 10 to 25 w / v%.

Examples of aldehydes that may be used as starting materials may include C ₁ -C ₁₀ aliphatic saturated aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, isobutyrylaldehyde or glyoxal; C ₃ -C ₁₀ aliphatic α ・ β-unsaturated aldehydes such as acrolein, methacrolein or crotonaldehyde; C ₆ -C ₂₀ aromatic aldehydes such as benzaldehyde, tolaldehyde, benzylaldehyde or phthalaldehyde; and derivatives of these aldehydes. These aldehydes can be used individually or as a mixture of any two or more of their types.

Examples of alcohols that can be used may include C ₁ -C ₁₀ aliphatic saturated alcohols, such as methanol, ethanol, isopropanol, butanol, 2-ethylhexanol or octanol; C ₅ -C ₁₀ alicyclic alcohols such as cyclopentanol or cyclohexanol; C ₂ -C ₁₀ diols such as ethylene glycol, propylene glycol or butanediol; C ₃ -C ₁₀ aliphatic unsaturated alcohols, such as allyl alcohol or metal alcohol; C ₆ -C ₂₀ aromatic alcohols, such as benzyl alcohol; and hydroxyoxetanes, such as 3-alkyl-3-hydroxymethyloxetane. These alcohols may be used individually or as a mixture of any two or more kinds thereof.

In the production method according to this embodiment, (a) the corresponding carboxylic acid ester can be obtained by reacting an aldehyde and an alcohol, or (b) the corresponding carboxylic acid ester can be obtained by reacting one or more kinds of alcohols.

In the case of obtaining a carboxylic acid ester from aldehyde and alcohol, there are no particular restrictions on the mass ratio of aldehyde and alcohol, and although the preparation can be performed in a wide range of mass ratios, for example, when the molar ratio of aldehyde to alcohol is from 10 to 1/1000, obtaining usually carried out with a molar ratio in the range from 1/2 to 1/50.

In the case of obtaining a carboxylic acid ester from two types of alcohols, there are also no particular restrictions on the mass ratios of the types of alcohols, and the preparation can be performed with a molar ratio of one type of alcohol to another type of alcohol from 10 to 1/1000 and preferably from 1/2 to 1/50.

The preparation of the carboxylic acid ester can be performed either batchwise or continuously using any arbitrary method, such as a vapor phase reaction, a liquid phase reaction or an irrigation reaction.

Although the reaction can be carried out in the absence of a solvent, it can also be carried out using a solvent that is inert to the reaction components, such as hexane, decane, benzene or dioxane.

Although the reaction can be carried out using a type of reaction known in the art, such as a reaction in a fixed bed, a reaction in a fluidized bed or a reaction in a stirred tank, when carrying out the reaction, for example, in a liquid phase, the reaction can be carried out using any a reaction tank, such as a bubble column reactor, a suction pipe reactor, or a stirred tank reactor.

The oxygen used to produce the carboxylic acid ester may be in the form of molecular oxygen, namely, gaseous oxygen per se or a mixed gas in which gaseous oxygen is diluted with a diluent that is inert to the reaction, for example, nitrogen gas or carbon dioxide, and preferably, air is used as the source of the initial oxygen due to the simplicity of the process, economy, and the like.

Although the partial pressure of oxygen varies according to the type of aldehyde, the type of alcohol and other reaction materials, the reaction conditions or the type of reaction vessel and the like, taking into account the practical application, the partial pressure of oxygen at the outlet of the reaction tank is in an interval that is less than the lower the limit value of the explosive range of its concentration, and is preferably regulated in such a way that, for example, is from 20 to 80 kPa. Although the reaction can be carried out in a wide range of arbitrary values of the reaction pressure, from low pressure to high pressure, the reaction is usually carried out at a pressure of from 0.05 to 2 MPa. From a safety point of view, it is preferable to set the total pressure so that the oxygen concentration in the gas leaving the reaction vessel does not exceed the explosive limit (oxygen concentration, for example, 8%).

In the case where a reaction is carried out to produce a carboxylic acid ester in a liquid phase and the like, the pH of the reaction system is preferably maintained between 6 and 9 by adding an alkali metal or alkaline earth metal compound (such as an oxide, hydroxide, carbonate) to the reaction system or carboxylate). These alkali metal or alkaline earth metal compounds may be used individually, or two or more kinds may be used in combination.

Although the preparation of the carboxylic acid ester can be carried out at a high temperature of 200 ° C and higher as a reaction temperature, the reaction temperature is preferably 30 to 200 ° C, more preferably 40 to 150 ° C and even more preferably 60 to 120 ° C. There are no special restrictions on the reaction time, and although it cannot be unconditionally determined, since it varies in accordance with the given conditions, it usually ranges from 1 to 20 hours.

Examples

Although the description below provides a more detailed explanation of this embodiment using examples, this embodiment is not limited to these examples. A person of ordinary skill in the art can perform the examples below, as well as various variants thereof, and such variants are also included in the scope of the claims for the patent.

In addition, in the examples and comparative examples, the determination of the amounts of Ni and X deposited on the carrier and the atomic ratio Ni / (Ni + X), the determination of the content of constituent elements (Si, Al, base metal, Mg) deposited on the carrier, the determination of the ratios nickel and constituent elements deposited on a carrier, analysis of the crystal structure of a nanoparticle, analysis of the chemical state of the metal components of the catalyst, morphological control and elemental analysis of nanoparticles, measurement of the spectra of the catalysts in the UV and visible region, analysis of x the physical state of nickel, the measurement of the physical properties of the support and catalyst (specific surface, pore diameter, pore volume), a visual study of the shape of the support and catalyst, and the measurement of the average particle diameter were performed in accordance with the methods described below.

Determination of the amounts of Ni and X deposited on a carrier and the atomic ratio of Ni / (Ni + X)

Nickel and X concentrations in the catalyst were quantified using an inductively coupled plasma atomic emission spectrometer IRIS Intrepid II Model XDL (ICP-AES, MS) manufactured by Thermo Fisher Scientific K.K.

Samples were prepared by weighing the catalyst in a Teflon decomposition vessel, sulfuric acid and hydrogen fluoride were added, decomposed by heating using an ETHOS TC microwave sample preparation device manufactured by Milestone General K.K. and evaporated to dryness with a heater, followed by the addition of nitric acid and hydrochloric acid to the precipitated residue, decomposed by heating using a microwave sample preparation device and used a clean liquid with a fixed volume obtained by decomposition for the sample.

This quantification method was performed using the ICP-AES proprietary standard method, and the value of the simultaneously tested blank sample was subtracted to determine the nickel and X contents in the catalyst and calculate their deposited amounts and atomic ratio.

Determination of the content of constituent elements (Si, Al, base metal, Mg) deposited on a carrier

Samples prepared by dissolving the support with sodium silicate and samples obtained by dissolving molten alkaline salt were prepared. The content of the base metal and / or Mg was measured in samples obtained by dissolution with sodium silicate, while the contents of Al and Si were measured in samples obtained by dissolution with molten alkaline salt using an inductively coupled plasma atomic emission spectrometer (ICP-AES) JY- 38P2 manufactured by Seiko Electronics Industry Co., Ltd., followed by calculation of atomic ratios of the obtained metal content values.

Determination of the ratio of Nickel and the constituent elements of the media

Atomic ratios were calculated from the contents of Ni, Al, Mg and the base metal, measured as described above.

Analysis of the crystal structure of a nanoparticle

Analysis of the crystal structure of the nanoparticles was performed using a Rint2500 powder X-ray diffraction (XRD) system manufactured by Rigaku Corp., using a copper tube as an X-ray source (40 kV, 200 mA), the measurement interval was from 5 to 65 degrees (0.02 degrees / step), the measurement speed of 0.2 deg./min and the width of the slots (scattering, divergence, reception) at 1 degree, 1 degree and 0.15 mm.

The catalyst samples were uniformly dispersed on a non-reflective sample plate and fixed with a neoprene film.

Analysis of the chemical state of the metal components of the catalyst

The chemical state of the metal components of the catalyst was analyzed using an XPS X-ray photoelectron spectroscopy (XPS) system ESCALAB 250 manufactured by Thermo Electron Corp., using Al Kα (15 kV × 10 mA) for an excitation source, with an analyzed surface area of approximately 1 mm (shape: oval) , using overview scanning (from 0 to 1, 100 eV) and narrow scanning (Ni2p) for absorption regions.

Samples for XPS measurement were prepared by grinding the catalyst particles with an agate mortar and pestle and sampling the resulting powder.

Morphological control and elemental analysis of nanoparticles

TEM bright field images, STEM dark field images, and STEM-EDS composition analyzes (point analysis, mapping, linear distribution) were obtained using a transmission electron microscope / scanning transmission electron microscope (TEM / STEM) model 3100FEF, manufactured by JEOL (accelerating voltage: 300 kV, equipped with an energy dispersive X-ray detector (EDX)).

Data analysis software consisted of Digital Micrograph ™ Ver. 1.70.16 (Gatan) for analytical images TEM and STEM (length measurement, analysis with Fourier transform) and NORAN System SIX Ver. 2.0 (Thermo Fisher Scientific) for the analysis of EDS data (mapping processing, quantitative composition calculations).

Samples for measurements were prepared by grinding the catalyst particles with a mortar and pestle, dispersed in ethanol and subjected to ultrasonic cleaning for about 1 minute, after which they were applied dropwise to a molybdenum (Mo) microgrid and exposed to air to obtain samples for observing TEM / STEM.

Measurement of the spectrum of the catalyst in the UV and visible region

The spectrum of the catalyst in the UV and visible region was measured using a V-550 UV and visible spectrophotometer manufactured by JASCO Corporation (integrating sphere, with a powder sample holder), during the measurement interval from 800 to 200 nm and at a scanning speed of 400 nm / min

Samples for measurements were prepared by grinding the catalyst particles with a mortar and pestle, placed in the holder of the powder sample and used for measurement in the UV and visible region.

Nickel chemical analysis

Ni Kα spectra were measured using a high resolution X-ray luminescent spectrometer (HRXRF) XFRA-190 manufactured by Techno Corp., and each of the obtained types of parameters was compared with parameters for standard substances (metallic nickel, nickel oxide) to evaluate the valence of the chemical state of nickel and t .P. in catalysts.

Samples for measurements were used for measurements without modification. The Ni Kα spectra were measured in the partial spectrum mode. In this case, a Ge (220) gap with a vertical divergence angle of 1 ° was used to analyze the crystal structure, and the excitation voltage and current were set at 35 kV and 80 mA, respectively. Filter paper was used for the absorber in standard samples, the counting time was selected for each sample from the catalyst samples, and measurements were performed so that the peak intensity in the Kα spectrum was 3000 counts / s or less, and the counting time was 10,000 counts or more. The measurements were repeated five times for each sample and the metal sample was measured before and after each repeated measurement. After smoothing (stochastic gradient method (SG), 7 points, 5 cycles) of the measured spectra, the position of the peak, the full width at half height (FWHM) and the asymmetry coefficient (Al) were calculated, and the position of the peak is considered as a displacement or chemical shift (ΔE ), relative to the measured value for the metal sample before and after the measurement of the sample.

Physical properties of the support and catalyst: specific surface, pore diameter, pore volume

Measurements were performed using an Autosoap 3MP instrument manufactured by Yuasa Ionics Inc., using nitrogen as an adsorbed gas (nitrogen adsorption method). The specific surface area was measured by the BET method, the pore diameter and pore size distribution were measured by the BJH method (Barrett-Joyner-Halenda) and the pore volume was measured by using an adsorbed amount at a maximum P / P ratio of ₀ .

Visual study of the form of the carrier and catalyst

A visual study of the carrier particles and the catalyst was carried out using a scanning electron microscope (SEM) X-650 manufactured by Hitachi, Ltd.

Measurement of the average particle diameter of the carrier and catalyst

The average particle diameter (based on volume) was measured using a LS230 particle diffraction analyzer manufactured by Beckman-Coulter, Inc.

Reference Example 1

Using 0.5 g of commercially available nickel oxide (Wako Pure Chemical Industries, Ltd.) as a catalyst, 1.0 g of methacrolein and 10 ml of methanol were charged to the reaction tank as a high pressure autoclave (total volume: 120 ml) made from SUS316 and equipped with a magnetic stirrer. After the autoclave was closed and the atmosphere in the internal space of the system was replaced with nitrogen gas, a nitrogen-based gas mixture containing 7 vol.% Oxygen was introduced into the vapor-phase unit and the total pressure inside the system was increased to 3.0 MPa. Then the reaction tank was placed in an oil bath and the reaction was carried out for 2 hours at a reaction temperature of 80 ° C with stirring. After cooling, the residual pressure was released and the autoclave was opened, after which the catalyst was filtered off and the filtrate was analyzed by gas chromatography. As a result, the amount of methyl methacrylate formed was 1.0 μmol.

Reference Example 2

The reaction was carried out in the same manner as in Reference Example 1, except for the use of nickel peroxide hydrate (Aldrich Corp.) for the catalyst instead of nickel oxide. As a result, the amount of methyl methacrylate formed was 5.3 μmol.

Reference Example 3

The reaction was carried out in the same manner as in Reference Example 1, except for using metallic nickel (Wako Pure Chemical Industries, Ltd.) instead of nickel oxide for the catalyst. As a result, the impossibility of the formation of methyl methacrylate was confirmed.

Example 1

(1) Preparation of catalyst

30 g of commercially available γ-alumina (Neobead, Mizusawa Industrial Chemicals, Ltd.) was added to a glass container containing 100 ml of distilled water, after which an aqueous solution of nickel nitrate and an aqueous solution of palladium chloride were added dropwise, stirring at 60 ° C, was added 0.5 N. aqueous sodium hydroxide solution to bring the pH of the aqueous solutions to 8, continued stirring for 1 hour, allowed to stand still, removed the supernatant, washed with distilled water until no more Cl ions were detected, dried for 16 hours at 105 ° C and burned in air for 5 hours at 600 ° C. Then, the resulting catalyst was subjected to reduction treatment for 1 hour at room temperature in a hydrogen atmosphere, obtaining a catalyst with deposited 1.5 wt.% Nickel and 0.5 wt.% Palladium (NiOPd / γ-alumina). The atomic ratio of Ni / (Ni + Pd) in the resulting catalyst was 0.84. Based on the results of X-ray diffraction (XRD), diffraction patterns inherent in nickel were not observed, thus confirming that nickel is present in an amorphous state. On the other hand, although it could not be defined as a pronounced peak, there was a broad peak corresponding to palladium crystals. Although the magnitude of this peak was close to the detection limit of powder X-ray diffraction (2 nm), calculations of the average crystallite size using the Scherrer formula gave a value of about 3 nm. With respect to the chemical state of Ni, a valency of 2 was confirmed based on the results of X-ray photoelectron spectroscopy (XPS).

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 3 to 4 nm (number average particle diameter: 3.8 nm) were deposited on the carrier. Elemental analysis (20 points) was performed for each of the observed nanoparticles by the method of auxiliary energy dispersive x-ray spectroscopy (EDX) and the presence of nickel and palladium in all particles was confirmed. The atomic ratio of nickel to palladium in these composite particles (average value) was 1.24.

(2) Synthesis of Carboxylic Acid Ester

0.2 g of the catalyst obtained in (1) above, 1.0 g of methacrolein and 10 ml of methanol were loaded into the reaction tank as a high pressure autoclave (total volume: 120 ml) made of SUS316 and equipped with a magnetic stirrer. After the autoclave was closed and the atmosphere in the internal space of the system was replaced with nitrogen, a nitrogen-based gas mixture containing 7 vol.% Oxygen was introduced into the vapor-phase unit and the pressure inside the system was increased to 3.0 MPa.

Then the reaction tank was placed in an oil bath and the reaction was carried out for 1 hour at a reaction temperature of 80 ° C and with stirring. After cooling, the residual pressure was released and the autoclave was opened, after which the catalyst was filtered off and the filtrate was analyzed by gas chromatography. As a result, the conversion of methacrolein was 18.2% and the selectivity for the formation of methyl methacrylate was 74.5%.

Example 2

The catalyst was obtained in the same manner as in (1) of Example 1, except for using an aqueous solution of silver nitrate instead of an aqueous solution of palladium chloride. The applied amounts of nickel and silver of the resulting catalyst were 1.6 wt.% And 1.3 wt.%, Respectively (NiOAg / γ-alumina). In addition, the atomic ratio of Ni / (Ni + Ag) was 0.69. Based on the results of X-ray powder diffraction (XRD), a broad peak was present corresponding to silver crystals. Calculations of the average size of its crystallites in accordance with the Scherrer formula gave a value of about 4 nm. On the other hand, the diffraction pattern inherent in nickel was not observed, thus confirming that nickel is present in an amorphous state. With respect to the chemical state of Ni, a valency of 2 was confirmed based on the results of X-ray photoelectron spectroscopy (XPS).

A visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle size distribution of 4 to 5 nm (number average particle diameter: 4.2 nm) were deposited on the carrier. Elemental analysis (20 points) was performed for each of the observed nanoparticles by the method of auxiliary energy dispersive x-ray spectroscopy (EDX) and the presence of nickel and silver in all particles was confirmed. The atomic ratio of nickel to silver in these composite particles (average value) was 0.81.

In addition, as a result of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), the absorption peaks of surface plasmons due to silver nanoparticles were not observed near 405 nm, while a wide absorption region was observed. characteristic of NiO ₂ over a wavelength range of 200 to 800 nm.

The reaction was carried out in the same manner as in (2) of Example 1 using this catalyst. As a result, the conversion rate of methacrolein was 6.2% and the selectivity for the formation of methyl methacrylate was 55.1%.

Example 3

The catalyst was obtained in the same manner as in (1) of Example 1, except for using an aqueous solution of hydrochloric acid instead of an aqueous solution of palladium chloride. The applied amounts of nickel and gold of the resulting catalyst were 1.4 wt.% And 0.4 wt.%, Respectively (NiOAu / γ-alumina). In addition, the atomic ratio of Ni / (Ni + Au) was 0.92. Based on the results of powder X-ray diffraction (XRD), a diffraction pattern inherent in nickel was not observed, thus confirming that nickel is present in an amorphous state. On the other hand, although it could not be defined as a pronounced peak, there was a wide peak corresponding to gold crystals. Although the magnitude of this peak was close to the detection limit of powder X-ray diffraction (2 nm), calculations of the average crystallite size using the Scherrer formula yielded a value of about 3 nm. With respect to the chemical state of Ni, a valency of 2 was confirmed based on the results of X-ray photoelectron spectroscopy (XPS).

A visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle size distribution of 2 to 3 nm (number average particle diameter: 3.2 nm) were deposited on the carrier. Elemental analysis (20 points) was performed for each of the observed nanoparticles by the method of auxiliary energy dispersive X-ray spectroscopy (EDX) and the presence of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 1.14.

As a result of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed near 530 nm, while a wide absorption region characteristic of NiO ₂ was observed , over the wavelength range from 200 to 800 nm.

The reaction was carried out in the same manner as in (2) of Example 1 using this catalyst. As a result, the conversion of methacrolein was 22.4%, and the selectivity for the formation of methyl methacrylate was 92.4%.

Reference Example 4

A 1.5 wt% nickel supported catalyst (NiO / γ-alumina) was obtained in the same manner as in (1) of Example 1, except that an aqueous palladium chloride solution was not added and hydrogen reduction was not performed. .

The reaction was carried out in the same manner as in (2) of Example 1 using this catalyst. As a result, the conversion of methacrolein was 3.1%, and the selectivity for the formation of methyl methacrylate was 35.2%.

Comparative Example 1

A 0.5 wt% palladium supported catalyst (Pd / γ-alumina) was obtained in the same manner as in (1) of Example 1, except that nickel nitrate was not added. In accordance with the results of X-ray powder diffraction (XRD), a broad peak was present corresponding to palladium crystals. Calculations of the average size of these crystallites in accordance with the Scherrer formula gave a value of about 3 nm.

The reaction was carried out in the same manner as in (2) of Example 1 using this catalyst. As a result, the conversion of methacrolein was 10.3% and the selectivity of methyl methacrylate formation was 52.4%.

Reference Example 2

A 1.5 wt% silver supported catalyst (Ag / γ-alumina) was obtained in the same manner as in (1) of Example 1, except that an aqueous solution of silver nitrate was used in place of an aqueous solution of palladium chloride and no nickel nitrate was added. In accordance with the results of powder x-ray diffraction (XRD) there was a wide peak corresponding to silver crystals. Calculations of the average size of these crystallites in accordance with the Scherrer formula gave a value of about 5 nm. As a result of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to silver nanoparticles were observed near 405 nm.

The reaction was carried out in the same manner as in (2) of Example 1 using this catalyst. As a result, the conversion rate of methacrolein was 2.1% and the selectivity for the formation of methyl methacrylate was 25.3%.

Reference Example 3

A catalyst coated with 1.5 wt.% Nickel and 1.4 wt.% Silver (NiAg / γ-alumina) was obtained in the same manner as in (1) of Example 1, except that an aqueous solution of silver nitrate was used instead of an aqueous solution of palladium chloride, the atmosphere of the heat treatment was changed from air to hydrogen.

Based on the results of powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), it was confirmed that nickel was reduced to a metallic state, and it was confirmed that an alloy of nickel and silver was formed.

The reaction was carried out in the same manner as in (2) of Example 1 using this catalyst. As a result, the methacrolein conversion was 1.5% and the methyl methacrylate (MMA) selectivity was 5.1%.

Table 1 presents the physical properties and reaction results for the catalysts used to produce the carboxylic acid ester of Examples 1-3, Reference Example 4, and Comparative Examples 1-3.

Table 1 No. Supported Composite Nanoparticles The amount of deposited Ni and X (wt.%) The atomic ratio of Ni / (Ni + X) (mol.%) Reaction results Ni X The degree of conversion (%) The selectivity of the formation of MMA (%) Example 1 NiOPd / Al ₂ O ₃ 1,5 0.5 0.84 18.2 74.5 Example 2 NiOAg / Al ₂ O ₃ 1,6 1.3 0.69 6.2 55.1 Example 3 NiOAu / Al ₂ O ₃ 1.4 0.4 0.92 22.4 92.4 Reference Example 4 NiO / Al ₂ O ₃ 1,5 0 - 3,1 35,2 Comparative Example 1 Pd / Al ₂ O ₃ 0 0.5 - 10.3 52,4 Reference Example 2 Ag / Al ₂ O ₃ 0 1,5 - 2.1 25.3 Reference Example 3 NiAg / Al ₂ O ₃ 1,5 1.4 - 1,5 5.1

Example 4

The magnesium compound was applied onto a commercially available silica (CARiACT Q-15, Fuji Silysia Chemical, Ltd.) by impregnation in a hot water bath using an aqueous solution containing magnesium acetate. Then, the obtained impregnated product was dried for 12 hours at 120 ° C, after which it was calcined in air for 6 hours at 600 ° C. As a result, a support was obtained based on the silica-magnesium oxide (SiO ₂ —MgO) system, which contained 5 wt.% Magnesium oxide based on Mg.

Then, 100 ml of an aqueous solution containing predetermined amounts of an aqueous solution of nickel nitrate and an aqueous solution of hydrochloric acid was heated at 80 ° C. 30 g of the support based on the silica-magnesium oxide system obtained above was added to this solution, after which the mixture was kept under stirring for one hour, thereby precipitating nickel and gold components on the support. Then this mixture was allowed to calmly settle and the supernatant was removed, after which it was washed with distilled water until the Cl ions were no longer detected. After that, the mixture was filtered, dried for 16 hours at 105 ° C and calcined for 3 hours in air at 500 ° C, obtaining a catalyst coated with 1.0 wt.% Nickel and 0.8 wt.% Gold (NiOAu / SiO _2- MgO). The atomic ratio of Ni / (Ni + Au) in the resulting catalyst was 0.81.

In accordance with the results of powder X-ray diffraction (XRD) for the catalyst described above, a wide diffraction peak characteristic of gold was observed, and calculations of the average crystallite size based on the distribution of the line width of the diffraction peak from the Au (111) plane gave a value of 3 nm. On the other hand, since there were no diffraction patterns due to nickel, it was assumed that nickel is present in the amorphous phase. With respect to the chemical state of nickel, a valency of 2 was confirmed based on the results of X-ray photoelectron spectroscopy (XPS).

The microstructure of the above catalyst was observed using a transmission electron microscope (TEM / STEM). As shown in figure 1, spherical particles with a particle diameter of from 2 to 3 nm are uniformly deposited on the surface of the carrier. The number average particle diameter of the nanoparticles was 3.0 nm (number of nanoparticles used for calculation: 100). Nanoparticles were observed with an additional magnification of the images (Fig. 2) to obtain data on the lattice structure. According to the results of analysis with the Fourier transform, the lattice planes corresponding to the lattice period for Au (200) (d = 2.039 Å) intersect at an angle of 90 °, respectively, indicating that this is an image of an Au (200) lattice. Thus, the nanoparticles contain crystalline gold. Lattice structures corresponding to the lattice periods of Au (200) and Au (111) were also observed in other particles.

Further, analysis of the composition at points using STEM-EDS for each nanoparticle showed that nickel and gold were detected in each particle. The average ratio of nickel and gold atoms in the nanoparticles (the number of nanoparticles used in the calculation: 50) was 0.82. Only trace amounts of nickel were detected by analyzing points outside the nanoparticles. Moreover, when analyzing the nano-regions of the particles observed (Fig. 3), the atomic ratio of Ni / Au in the center of the particles (measurement point 1) was 0.73, while its value at the edge of the particle (measurement point 2) was 2.95. Only trace amounts of nickel were determined in other parts of the particles (measurement point 3). As a result of such measurements, 20 times more nickel was detected at the edges of all particles. The observed distribution of nickel and gold was almost completely consistent with the data obtained on the basis of the results of elemental mapping of EDS. In addition, in accordance with the linear profiles of the composition (Fig. 4), nickel was distributed in such a way that its distribution profile surrounded the distribution profile of gold in all scanning directions (1, 2). Thus, since nickel is distributed over gold and nickel is detected in large quantities at the edges of the particles, the nanoparticles contained in the above catalyst are considered to have a shape in which the surfaces of the gold nanoparticles are coated with nickel.

Figure 5 shows the absorption spectra of the particles of the catalyst NiOAu / SiO ₂ -MgO obtained using spectroscopy in the UV and visible spectral region (UV-Vis). The Au / SiO ₂ -MgO sample has gold nanoparticles supported on the same support (the catalyst obtained in comparative example 4 described below), and the absorption of surface plasmons due to gold nanoparticles appears near 530 nm. A NiO / SiO ₂ -MgO sample (the catalyst obtained in Reference Example 5 described later) and a NiO ₂ / SiO _2- MgO sample (synthesized by oxidative treatment of the sample obtained in Reference Example 5 using hypochlorous acid) have fine NiO particles and NiO ₂ deposited on the same carrier and a wide absorption region over the wavelength range from 200 to 800 nm, observed for NiO ₂ / SiO ₂ -MgO, were not observed for NiO / SiO ₂ -MgO. This result means that a wide absorption region over the wavelength range from 200 to 800 nm appears in the case of highly oxidized nickel oxide (NiO ₂ ). In contrast, the absorption of surface gold plasmons near 530 nm does not occur in the case of NiOAu / SiO ₂ -MgO, and a wide absorption region characteristic of NiO ₂ is observed over the wavelength range from 200 to 800 nm.

Based on these results, it is believed that NiOAu / SiO _{2 —} MgO catalysts have a form in which gold atoms are not present on their surface, and most likely the surfaces of the gold nanoparticles are coated with highly oxidized nickel oxide.

0.3 g of the catalyst obtained above, 1.0 g of methacrolein and 10 ml of methanol were charged into the reaction tank as a high pressure autoclave (total volume: 120 ml) made from SUS316 and equipped with a magnetic stirrer, and after the autoclave was closed and the atmosphere in the internal space of the system was replaced with nitrogen gas, a nitrogen-based gas mixture containing 7 vol.% oxygen was introduced into the vapor-phase unit, and the pressure inside the system was increased to 5.0 MPa.

Then the reaction tank was placed in an oil bath and the reaction was carried out for 2 hours at a reaction temperature of 60 ° C and with stirring. After cooling, the residual pressure was released and the autoclave was opened, after which the catalyst was filtered off and the filtrate was analyzed by gas chromatography.

As a result, the methacrolein conversion ratio was 61.3% and the methyl methacrylate formation selectivity was 95.7%.

Reference Example 5

A nickel supported catalyst in an amount of 1.0 wt.% (Ni / SiO ₂ —MgO) was obtained in the same manner as in Example 4, except that an aqueous solution of hydrochloric acid was not added.

The reaction was carried out in the same manner as in example 4 using this catalyst. As a result, the conversion rate of methacrolein was 3.2% and the selectivity for the formation of methyl methacrylate was 30.1%.

Reference Example 4

A gold supported catalyst in an amount of 0.9 wt.% (Au / SiO ₂ —MgO) was obtained in the same manner as in Example 4, except that nickel nitrate was not added. The average crystallite size, calculated according to powder X-ray diffraction (XRD), was 3 nm.

The reaction was carried out in the same manner as in example 4 using this catalyst. As a result, the conversion of methacrolein was 9.7% and the selectivity for the formation of methyl methacrylate was 75.0%.

Reference Example 5

A catalyst coated with 1.0 wt.% Nickel and 0.8 wt.% Gold (NiAu / SiO ₂ —MgO) was prepared in the same manner as in Example 4, except that the heat treatment atmosphere was changed from air to hydrogen. In accordance with the results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) for this catalyst, nickel was reduced to a metallic state and it was confirmed that an alloy of nickel and gold was formed.

The reaction was carried out in the same manner as in example 4 using this catalyst. As a result, the conversion of methacrolein was 11.3% and the selectivity for the formation of methyl methacrylate was 62.4%.

Reference Example 6

A catalyst supported with 1.1 wt.% Iron and 0.9 wt.% Gold (Fe ₂ O ₃ Au / SiO ₂ —MgO) was obtained in the same manner as in Example 4, except for using iron nitrate instead of nickel nitrate. The atomic ratio Fe / (Fe + Au) in the resulting catalyst was 0.81.

In accordance with the results of spectrometry in the UV and visible region (UV-Vis) for this catalyst, absorption of surface plasmons due to gold nanoparticles (at about 530 nm) was observed.

The reaction was carried out in the same manner as in example 4 using this catalyst. As a result, the conversion rate of methacrolein was 10.4% and the selectivity for the formation of methyl methacrylate was 55.2%.

Reference Example 7

A catalyst coated with 1.2 wt.% Cobalt and 0.8 wt.% Gold (Co ₃ O ₄ Au / SiO _{2 —} MgO) was prepared in the same manner as in Example 4, except for using cobalt nitrate instead of nickel nitrate. The atomic Co / (Co + Au) ratio in the resulting catalyst was 0.83.

In accordance with the results of spectrometry in the UV and visible region (UV-Vis) for this catalyst, absorption of surface plasmons due to gold nanoparticles (at about 530 nm) was observed.

The reaction was carried out in the same manner as in example 4 using this catalyst. As a result, the conversion rate of methacrolein was 2.6% and the selectivity for the formation of methyl methacrylate was 45.8%.

Reference Example 8

A catalyst coated with 1.0 wt.% Copper and 0.8 wt.% Gold (CuOAu / SiO _{2 —} MgO) was obtained in the same manner as in Example 4, except for using copper nitrate instead of nickel nitrate. The atomic ratio of Cu / (Cu + Au) in the resulting catalyst was 0.79.

In accordance with the results of spectrometry in the UV and visible region (UV-Vis) for this catalyst, absorption of surface plasmons due to gold nanoparticles (at about 530 nm) was observed.

The reaction was carried out in the same manner as in example 4 using this catalyst. As a result, the conversion of methacrolein was 9.2% and the selectivity for the formation of methyl methacrylate was 58.1%.

Table 2 presents the physical properties and reaction results for the catalysts used to produce the carboxylic acid ester of Example 4, Reference Example 5, and Comparative Examples 4-8.

table 2 No. Supported Composite Nanoparticles The amount of deposited Ni and Au (wt.%) The atomic ratio of Ni / (Ni + Au) (mol.%) Reaction results Ni Au The degree of conversion (%) The selectivity of the formation of MMA (%) Example 4 NiOAu / SiO ₂ -MgO 1,0 0.8 0.81 61.3 95.7 Reference Example 5 NiO / SiO ₂ -MgO 1,0 0 1.00 3.2 30.1 Reference Example 4 Au / SiO ₂ -MgO 0 0.9 - 9.7 75.0 Reference Example 5 NiAu / SiO ₂ -MgO 1,0 0.8 0.81 11.3 62,4 Reference Example 6 Fe ₂ O ₃ Au / SiO ₂ -MgO 1.1 ¹⁾ 0.9 0.81 ⁴⁾ 10,4 55.2 Reference Example 7 Co ₃ O ₄ Au / SiO ₂ -MgO 1.2 ²⁾ 0.8 0.83 ⁵⁾ 2.6 45.8 Reference Example 8 CuOAu / SiO ₂ -MgO 1,0 ³⁾ 0.8 0.79 ⁶⁾ 9.2 58.1 ^{1) the} applied amount of Fe, ^{2) the} applied amount of Co, ^{3) the} applied amount of Cu,
⁴⁾ atomic ratio Fe / (Fe + Au), ⁵⁾ atomic ratio Co / (Co + Au), ⁶⁾ atomic ratio Cu / (Cu + Au)

Examples 5-10, reference example 6, comparative example 9

2 kg of silica sol (Snowtex N-30 manufactured by Nissan Chemical Industries, Ltd. (SiO ₂ content: 30 wt.%)) Was added to 128 g titanium dioxide sol (STS-018 manufactured by Ishihara Techno Co., Ltd. (TiO content ₂ : 30 wt.%)) And mixed, after which the suspension was kept for 24 hours at 15 ° C and spray dried in a spray drying device with a set gas outlet temperature of 130 ° C to obtain a solid-state material.

Then a support was prepared based on a silica-titanium dioxide system by firing for 2 hours in air at 300 ° C, and then for 3 hours at 600 ° C. The ratio of silica / titanium dioxide based on oxides was 93.6 / 6.0. The specific surface when determined by nitrogen adsorption was 236 m ² / g, and the pore volume was 0.26 ml / g. The average particle diameter of the carrier was 60 μm in accordance with the results obtained by the laser diffraction particle size analyzer. In addition, the shape of the carrier was determined to be nearly spherical based on visual studies using a scanning electron microscope (SEM).

Then, 30 g of a carrier based on a silica-titanium dioxide system prepared as described above was added to a glass container containing 100 ml of distilled water, after which, while stirring at 90 ° C, an aqueous solution of nickel nitrate was added dropwise in predetermined amounts and aqueous solution of hydrochloric acid; the pH of the aqueous solution was adjusted to 7 by the addition of 0.5 n. aqueous sodium hydroxide solution and stirring was continued for 1 hour. After this, the aqueous solution was allowed to calmly settle and the supernatant was removed, then the precipitate was washed with distilled water until the Cl ions were no longer detected, dried for 16 hours at 105 ° C and calcined for 3 hours at 400 ° C in air, a catalyst in which the atomic ratio of Ni / (Ni + Au) was varied in the range from 0 to 1.0 (while the total amount of nickel and gold remained constant), and then the reaction was carried out in the same manner as in example 4. Table 3 presents the physical properties of the obtained catalyst s, along with the activity of formation of methyl methacrylate (MMA) per unit molar amount of nickel and gold (mol MMA / h / mol Ni + Au).

Table 3 No. Supported Composite Nanoparticles The amount of deposited Ni and Au (wt.%) The atomic ratio of Ni / (Ni + Au) (mol.%) The activity of the formation of MMA (mol MMA / h / mol Ni + Au) Ni Au Example 5 NiOAu / SiO ₂ -TiO ₂ 1,2 0.4 0.91 25,2 Example 6 NiOAu / SiO ₂ -TiO ₂ 1,1 0.7 0.83 41.3 Example 7 NiOAu / SiO ₂ -TiO ₂ 0.9 1.3 0.70 63.5 Example 8 NiOAu / SiO ₂ -TiO ₂ 0.8 1.7 0.61 52.1 Example 9 NiOAu / SiO ₂ -TiO ₂ 0.7 2.1 0.53 43.7 Example 10 NiOAu / SiO ₂ -TiO ₂ 0.3 3,5 0.22 14.0 Reference Example 6 NiO / SiO ₂ -TiO ₂ 1.3 0 1.00 0.4 Reference Example 9 Au / SiO ₂ -TiO ₂ 0 4.3 0 8.3

Example 11

The reaction for the formation of methyl acrylate was carried out using the same procedure and the same reaction conditions as in Example 4, except for the use of the catalyst obtained in Example 4 (NiOAu / SiO _{2 —} MgO) and the participation of acrolein instead of methacrolein in the reaction.

As a result, the conversion rate of acrolein was 71.3% and the selectivity for the formation of methyl acrylate was 96.8%.

Example 12

The reaction of formation of ethyl acrylate was carried out using the same methodology and the same reaction conditions as in Example 4, except for the use of the catalyst obtained in Example 4 (NiOAu / SiO ₂ -MgO), participation of acrolein instead of methacrolein in the reaction, and participation of ethanol in the reaction instead of methanol.

As a result, the conversion rate of acrolein was 81.5% and the selectivity for the formation of ethyl acrylate was 96.2%.

Example 13

The ethylbenzoate formation reaction was carried out using the same procedure and the same reaction conditions as in Example 4, except for the use of the catalyst obtained in Example 4 (NiOAu / SiO ₂ -MgO), participation of benzaldehyde instead of methacrolein and participation of ethanol in the reaction instead of methanol.

As a result, the conversion of benzaldehyde was 88.2% and the selectivity of ethylbenzoate formation was 98.2%.

Example 14

The reaction for the formation of methyl methacrylate was carried out using the same procedure and the same reaction conditions as in Example 4, except for the use of the catalyst obtained in Example 4 (NiOAu / SiO _{2 —} MgO) and the participation of metal alcohol in the reaction instead of methacrolein.

As a result, the degree of metal alcohol conversion was 59.2% and the selectivity for the formation of methyl acrylate was 94.1%.

Example 15

The reaction for the formation of ethyl acetate was carried out using the same procedure and the same reaction conditions as in Example 4, except for using the catalyst obtained in Example 4 (NiOAu / SiO _{2 —} MgO), participating in the reaction of ethanol instead of methacrolein and methanol and carrying out the reaction at a temperature of 80 ° C.

As a result, the degree of ethanol conversion was 30.4% and the ethyl acetate selectivity was 91.2%.

Example 16

The methylglycolate formation reaction was carried out using the same procedure and the same reaction conditions as in Example 4, except for the use of the catalyst obtained in Example 4 (NiOAu / SiO ₂ -MgO) and the participation of ethylene glycol in place of methacrolein.

As a result, the conversion of ethylene glycol was 42.4% and the selectivity for the formation of methyl glycolate was 90.5%.

Example 17

(1) Media Preparation

An aqueous solution in which 4.16 kg of aluminum nitrate nonahydrate and 540 g of 60% nitric acid was dissolved in 5.0 l of pure water was gradually added while stirring in 20.0 kg of a solution of silica sol with colloidal particles with a diameter of 10 to 20 nm, maintained at 15 ° C (Snowtex N-30 manufactured by Nissan Chemical Industries, Ltd. (SiO ₂ content: 30 wt.%)), Obtaining a mixed suspension of silica sol and aluminum nitrate. Thereafter, the mixed suspension was aged by aging at 50 ° C. for 24 hours. After cooling to room temperature, the mixed suspension was spray dried in a spray drying apparatus with a set gas outlet temperature of 130 ° C to obtain a solid material.

Then, the obtained solid-state material was placed in a layer about 1 cm thick in an open-top stainless steel container, after which it was heated in an electric furnace from room temperature to 300 ° C for 2 hours and then kept at this temperature for 3 hours. After additional heating to 600 ° C for 2 hours, followed by keeping it at this temperature for 3 hours, the solid-state material was gradually cooled, obtaining a carrier based on a silica-alumina system. The amount of aluminum in the resulting support was 10 mol%, based on the total molar amount of silicon and aluminum. The specific surface determined by nitrogen adsorption was 145 m ² / g, the pore volume was 0.27 ml / g, and the average pore diameter was 8 nm. The average particle diameter of the carrier, in accordance with the measurement results by the particle size analyzer by laser diffraction, was 62 μm. In addition, it was found that the shape of the carrier is close to spherical, based on visual studies using a scanning electron microscope (SEM).

(2) Preparation of catalyst

1.0 l of a solution containing 22.30 g of nickel nitrate hexahydrate and 20 ml of an aqueous solution of hydrochloric acid with a concentration of 1.3 mol / l was heated to 80 ° C. 300 g of the support based on the silica-alumina system obtained above were placed in this aqueous solution, after which the pH of the aqueous solution was adjusted to 7 by adding 0.5 N. an aqueous solution of sodium hydroxide, maintaining at 80 ° C and with stirring, and stirring was continued for 1 hour, precipitating the components of Nickel and gold on the media.

Then, after keeping in a calm state, the supernatant was removed and the precipitate was washed several times with distilled water, the liquid was filtered. After drying the filtrate for 16 hours at 105 ° C, the product was calcined for 5 hours at 450 ° C in air to obtain a catalyst coated with 1.43 wt.% Nickel and 1.45 wt.% Gold (NiOAu / SiO ₂ -Al ₂ O ₃ ). The atomic ratio Ni / (Ni + Au) in the obtained catalyst was 0.768, and the atomic ratio Ni / Al was 0.144. The specific surface, as determined by nitrogen adsorption, was 150 m ² / g, the pore volume was 0.28 ml / g, and the average pore diameter was 8 nm. The average particle diameter of the catalyst, in accordance with the measurement results of the particle size analyzer by laser diffraction, was 61 μm. In addition, it was found that the shape of the catalyst is close to spherical, based on visual studies using a scanning electron microscope (SEM).

Based on the results of powder X-ray diffraction (XRD), a diffraction pattern corresponding to nickel was not observed, and it was confirmed that nickel is present in an amorphous state. On the other hand, although it could not be defined as a pronounced peak, there was a wide peak corresponding to gold crystals. Although the magnitude of this peak was close to the detection limit of powder X-ray diffraction (2 nm), calculations of the average crystallite size using the Scherrer formula gave a value of about 3 nm.

With respect to the chemical state of Ni, a valency of 2 was confirmed based on the results of X-ray photoelectron spectroscopy (XPS). Moreover, the chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the high resolution X-ray luminescence (HRXRF), and was defined as a chemical state different from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα- spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.458 and the chemical shift (ΔE) was 0.331. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 3.2 nm). A visual study of enlarged images of nanoparticles showed that the nanoparticles had a lattice structure corresponding to the lattice period of Au (111). Point composition analysis by STEM-EDS for each nanoparticle confirmed that nickel and gold were contained in each particle. The average ratio of nickel and gold atoms in composite nanoparticles (the number of nanoparticles used in the calculation: 50) was 0.83. Moreover, in the analysis of the nano-regions of the observed particles, nickel was distributed over gold in all particles, and more nickel was found at the edges of all particles.

Further, when studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), the absorption peaks of surface plasmons due to gold nanoparticles were not observed near 530 nm, while a wide absorption region was observed, characteristic for NiO ₂ , over a wavelength range of 200 to 800 nm.

Based on these results, it was found that the nanoparticles contained in the catalyst according to this embodiment have a shape in which the surface of the gold nanoparticles is coated with nickel and have a surface electronic state different from that for gold nanoparticles containing a single metal component.

(3) Synthesis of carboxylic acid ester

200 g of the catalyst (NiOAu / SiO ₂ -Al ₂ O ₃ ) obtained above was loaded into a stirred stainless steel reaction tank having a 1.2 liter liquid phase assembly and equipped with a catalyst separator. The oxidation reaction of the formation of a carboxylic acid ester was then carried out using an aldehyde and an alcohol, or one or more types of alcohols, stirring the contents of the reaction tank at a stirrer end speed of 4 m / s. A solution of 36.7 wt.% Methacrolein in methanol was continuously fed into the reaction tank at a flow rate of 0.6 l / h, along with a continuous supply of a solution of 1-4 wt.% NaOH in methanol at a flow rate of 0.06 l / h, while being blown air so that the reaction temperature is 80 ° C and the outlet oxygen concentration at the reaction pressure of 0.5 MPa is 4.0 vol.% (which is equivalent to the partial oxygen pressure of 0.02 MPa), and the concentration of NaOH supplied to the reaction tank , adjusted so that the pH of the reaction system was 7. The reaction first product is continuously recovered from the outlet of the reaction tank overflow and reactivity was investigated by analyzing by gas chromatography.

200 hours after the start of the reaction, the methacrolein conversion was 61.5%, the methyl methacrylate formation selectivity was 94.6%, and the methyl methacrylate formation activity per unit mass of the catalyst was 7.60 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 61.7%, a methyl methacrylate formation selectivity of 94.7% and a methyl methacrylate formation activity of 7.628 mol / h / kg of catalyst.

In addition, when the concentrations of Ni, Au and Si ions in the reaction solution were analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm or less in both cases, and the concentration Si was 1 ppm or less in both cases, thus confirming that peeling and leaching of Ni and Au, which are active components of the catalyst, as well as leaching of Si, which is a component of the support, were suppressed. When the catalyst was recovered after undergoing a reaction for 500 hours and examined by a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the pore volume of the catalyst, as determined by nitrogen adsorption, was 0.28 ml / g, and the average pore diameter was 8 nm.

Further, a visual study of the catalyst after the reaction using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm (number average particle diameter: 3.0 nm) were deposited on the support. Point analysis of the composition using STEM-EDS for each nanoparticle confirmed that nickel and gold were contained in each nanoparticle. The average ratio of nickel and gold atoms in composite nanoparticles (the number of nanoparticles used in the calculation: 50) was 0.85. In addition, in the analysis of the nano-regions of the observed particles, nickel was distributed over gold in all particles, and more nickel was found at the edges of all particles. In addition, when studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed near 530 nm.

Based on these results, it was confirmed that the physical properties of the catalyst and the structure of the nanoparticles of this embodiment did not change after the reaction compared to the initial state.

Example 18

A silica-alumina-based carrier having a specific surface area of 110 m ² / g was prepared according to the same procedure as in (1) of Example 17, except that aluminum nitrate was added so that the amount of aluminum amounted to 15 mol.% calculated on the total molar amount of silicon and aluminum, and set the firing temperature of 700 ° C.

The catalyst was then prepared in the same manner as in (2) of Example 17, except for using the above support and using 4.46 g of nickel nitrate hexahydrate.

The amount of supported nickel and gold in the resulting catalyst was 0.25 wt.% And 1.43 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.370, and the atomic ratio of Ni / Al was 0.017.

In accordance with the results of powder x-ray diffraction (XRD) there was a wide peak corresponding to gold crystals. The average size of its crystallites, calculated according to the Scherrer formula, was approximately 3 nm. On the other hand, diffraction patterns due to nickel were not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.452 and the chemical shift (ΔE) was 0.341. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 3.2 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX) and the presence of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.81.

In addition, when studying changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17 using this catalyst. As a result, the conversion rate of methacrolein after completion of the reaction for 200 hours was 58.4%, the selectivity for the formation of methyl methacrylate was 94.7%, and the activity for the formation of methyl methacrylate per unit mass of the catalyst was 7.220 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 58.6%, a methyl methacrylate formation selectivity of 94.9% and a methyl methacrylate formation activity of 7.260 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined by a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.4 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 19

300 g of commercially available silica (CARiACT Q-10, Fuji Silysia Chemical, Ltd.) was added to a glass container containing 500 ml of distilled water, after which 98.5 g of aluminum nitrate nonahydrate as an aluminum source was gradually added to the solution, and dissolved in a solution of silica gel and evaporated with drying in a hot water bath.

The obtained solid-state material was placed in a layer about 1 cm thick in an open-top stainless steel container, after which it was heated in an electric furnace from room temperature to 300 ° C for 2 hours and then kept at this temperature for 3 hours. After additional heating to 600 ° C for 2 hours, followed by keeping it at this temperature for 3 hours, the solid-state material was gradually cooled, obtaining a carrier based on a silica-alumina system. The amount of aluminum in the resulting support was 5 mol%, based on the total molar amount of silicon and aluminum. The specific surface, as determined by nitrogen adsorption, was 183 m ² / g.

Then, the catalyst was obtained in the same manner as in (2) of Example 17, except for the use of the above support and the use of nickel nitrate hexahydrate in an amount of 66.89 g.

The amount of supported nickel and gold in the resulting catalyst was 4.50 wt.% And 1.44 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.913, and the atomic ratio of Ni / Al was 0.914.

Based on the results of X-ray powder diffraction (XRD), there was a broad peak corresponding to gold crystals. The average size of its crystallites, calculated according to the Scherrer formula, was approximately 3 nm. On the other hand, diffraction patterns due to nickel were not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.403, and the chemical shift (ΔE) was 0.336. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 2.9 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the presence of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.85.

In addition, according to the results of a study of changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17 using this catalyst. As a result, the conversion rate of methacrolein after completion of the reaction for 200 hours was 57.6%, the selectivity for the formation of methyl methacrylate was 93.6%, and the activity for the formation of methyl methacrylate per unit mass of the catalyst was 7.038 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 57.1%, a methyl methacrylate formation selectivity of 93.8% and a methyl methacrylate formation activity of 6.992 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.1 nm, thus showing the practical absence of any changes after the reaction compared to the initial state.

Example 20

A commercially available silica-alumina compound (N631HN manufactured by Nikki Chemical Co., Ltd., the amount of alumina based on the total molar amount of silicon and aluminum: 30 mol%) was placed in a approximately 1 cm thick layer in a stainless steel container with open top, after which it was heated in an electric oven from room temperature to 300 ° C for 2 hours and then kept at this temperature for 3 hours. After additional heating to 800 ° C for 2 hours, followed by aging at this temperature for 3 hours, the solid-state material was gradually cooled, obtaining the target substance. The specific surface, as determined by nitrogen adsorption, was 348 m ² / g.

Then, the catalyst was obtained in the same manner as in (2) of Example 17, except for using the above support. The amount of supported nickel and gold in the resulting catalyst was 1.40 wt.% And 1.42 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.768, and the atomic ratio of Ni / Al was 0.046.

According to the results of powder x-ray diffraction (XRD) there was a wide peak corresponding to gold crystals. The average size of its crystallites, calculated according to the Scherrer formula, was approximately 3 nm. On the other hand, diffraction patterns due to nickel were not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.492 and the chemical shift (ΔE) was 0.329. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm (number average particle diameter: 3.0 nm) were deposited on the carrier. Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the presence of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.80.

In addition, according to the results of a study of changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17, except for the use of this catalyst. As a result, the methacrolein conversion rate after the reaction for 200 hours was 60.4%, the methyl methacrylate formation selectivity was 94.3%, and the methyl methacrylate formation activity per unit mass of the catalyst was 7.436 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 61.0%, a methyl methacrylate formation selectivity of 94.2% and a methyl methacrylate formation activity of 7.501 mol / h / kg of catalyst.

In addition, when the concentrations of Ni, Au and Si ions in the reaction solution were analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm or less in both cases, and the concentration Si was 1 ppm or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.2 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 21

An aqueous solution in which 4.86 kg of aluminum nitrate nonahydrate and 1.53 kg of rubidium nitrate was dissolved in 5.0 l of pure water was gradually fed with stirring in 20.0 kg of a solution of silica sol with colloidal particles with a diameter of 10 to 20 nm maintained at 15 ° C (TX11561 manufactured by Nalco Co., Ltd. (SiO ₂ content: 30 wt.%)) to obtain a mixed suspension of silica sol, aluminum nitrate and rubidium nitrate. Then, the mixed suspension was aged by aging at room temperature for 24 hours. Then, the mixed suspension was spray dried in a spray drying apparatus with a set gas outlet temperature of 130 ° C. to obtain a solid material. The obtained solid-state material was placed in a layer about 1 cm thick in an open-top stainless steel container, after which it was heated in an electric furnace from room temperature to 400 ° C for 2 hours and then kept at this temperature for 3 hours. After additional heating to 580 ° C for 2 hours, followed by keeping it at this temperature for 3 hours, the solid-state material was gradually cooled, obtaining a carrier based on the silica-alumina-rubidium oxide system. The amount of aluminum was 11.5 mol%, based on the total molar amount of silicon and aluminum, and the atomic ratio (alkali metal + 1/2 × alkaline earth metal + 1/3 × rare earth metal) / Al was 0.80. The specific surface, as determined by nitrogen adsorption, was 127 m ² / g. The average particle diameter of the carrier, according to the results of measurements by the particle size analyzer by laser diffraction, was 64 μm. In addition, it was found that the shape of the carrier is close to spherical, based on visual studies using a scanning electron microscope (SEM).

Further, 1.0 l of a solution containing 14.9 g of nickel nitrate hexahydrate and 13 ml of a 1.3 mol / L aqueous solution of hydrochloric acid was heated to 90 ° C. 300 g of the support based on the silica-alumina-rubidium oxide system obtained above were placed in this aqueous solution and then kept at 90 ° C and with stirring, stirring was continued for 1 hour, precipitating nickel and gold components on the support.

Then, after keeping in a calm state, the supernatant was removed and the precipitate was washed several times with distilled water, the liquid was filtered. After drying the filtrate for 16 hours at 105 ° C, the product was calcined for 3 hours at 500 ° C in air, obtaining a catalyst coated with 0.97 wt.% Nickel and 0.95 wt.% Gold (NiOAu / SiO ₂ -Al ₂ O ₃ -Rb ₂ O). The atomic ratio Ni / (Ni + Au) in the obtained catalyst was 0.774, and the atomic ratio Ni / Al was 0.11, while the atomic ratio Ni / Rb was 0.137. According to the results of powder X-ray diffraction (XRD), a diffraction pattern corresponding to nickel was not observed, thus confirming that nickel is present in an amorphous state. A peak was present, although broad, as described above, corresponding to gold crystals, and the average crystallite size was 3.0 nm.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.432, and the chemical shift (ΔE) was 0.345. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 2.8 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and it was confirmed that nickel and gold were contained in all particles. The atomic ratio of nickel to gold in these composite particles (average value) was 1.02.

In addition, according to the results of a study of changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17, with the exception of using this catalyst and using an amount of catalyst of 240 g. As a result, the conversion of methacrolein after completion of the reaction for 200 hours was 55.3%, the selectivity for the formation of methyl methacrylate was 95 , 1%, and the activity of the formation of methyl methacrylate per unit mass of the catalyst was 5.721 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 54.9%, a methyl methacrylate formation selectivity of 95.3% and a methyl methacrylate formation activity of 5.692 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.2 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 22

A carrier based on a silica-alumina-strontium oxide system was prepared in the same manner as in Example 21, except that 2.90 kg of strontium nitrate was used instead of rubidium nitrate. The amount of aluminum was 11.5 mol.% Based on the total molar amount of silicon and aluminum, and the atomic ratio (alkali metal + 1/2 × alkaline earth metal + 1/3 × rare earth metal) / Al was 0.53. The specific surface, as determined by nitrogen adsorption, was 138 m ² / g. The average particle diameter of the carrier, in accordance with the measurement results by the particle size analyzer by laser diffraction, was 62 μm. In addition, it was found that the shape of the carrier is close to spherical, based on visual studies using a scanning electron microscope (SEM).

Then, a catalyst was obtained with 3.98 wt.% Nickel and 0.97 wt.% Gold (NiOAu / SiO ₂ -Al ₂ O ₃ -SrO) deposited in the same manner as in Example 21, except that the specified higher carrier, and the amount of nickel nitrate hexahydrate was 59.46 g.

The atomic ratio Ni / (Ni + Au) in the resulting catalyst was 0.932, and the atomic ratio Ni / Al was 0.421, while the atomic ratio Ni / Sr was 0.398.

Based on the results of X-ray powder diffraction (XRD), there was a broad peak corresponding to gold crystals. The average crystallite size calculated by Scherrer’s formula was approximately 3 nm. On the other hand, a diffraction pattern due to nickel was not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.464, and the chemical shift (ΔE) was 0.339. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm (number average particle diameter: 3.0 nm) were deposited on the carrier. Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 1.1.

In addition, according to the results of a study of changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17, except that this catalyst was used, and the amount of catalyst was 240 g. As a result, the conversion of methacrolein after the reaction for 200 hours was 52.5%, selectivity methyl methacrylate formation was 95.0%, and methyl methacrylate formation activity per unit mass of catalyst was 5.426 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 52.8%, a methyl methacrylate formation selectivity of 94.9% and a methyl methacrylate formation activity of 5.451 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.2 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 23

A carrier based on a system of silica-alumina-magnesium-lanthanum was obtained in the same manner as in Example 21, except that aluminum nitrate nonahydrate was used in an amount of 1.88 kg and 3.5 kg of magnesium nitrate and 1 were added. 0 kg of lanthanum chloride hydrate instead of rubidium nitrate. The amount of aluminum was 4.8 mol%, based on the total molar amount of silicon and aluminum, and the atomic ratio (alkali metal + 1/2 alkaline earth metal + 1/3 alkaline earth metal) / Al was 1.514. The specific surface, as determined by nitrogen adsorption, was 115 m ² / g. The average particle diameter of the carrier, in accordance with the measurement results by the particle size analyzer by laser diffraction, was 62 μm. In addition, it was found that the shape of the carrier is close to spherical, based on visual studies using a scanning electron microscope (SEM).

Then, the catalyst was obtained in the same manner as in Example 21, except for the use of the above support and the use of nickel nitrate hexahydrate in an amount of 4.46 g.

The applied amounts of nickel and gold in the resulting catalyst were 0.25 wt.% And 1.02 wt.%, Respectively. In addition, the atomic ratio Ni / (Ni + Au) in the obtained catalyst was 0.451, and the atomic ratio Ni / Al was 0.064, while the atomic ratio Ni / (Mg + La) was 0.061.

In accordance with the results of powder x-ray diffraction (XRD) there was a wide peak corresponding to gold crystals. The average crystallite size calculated by Scherrer’s formula was approximately 3 nm. On the other hand, a diffraction pattern due to nickel was not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.493, and the chemical shift (ΔE) was 0.335. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 3.2 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 1.09.

In addition, according to the results of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17, with the exception of using this catalyst and the amount of catalyst used was 240 g. As a result, the conversion of methacrolein after completion of the reaction for 200 hours was 53.6%, the selectivity for the formation of methyl methacrylate was 95 , 3%, and the activity of the formation of methyl methacrylate per unit mass of the catalyst was 5.557 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 53.3%, a methyl methacrylate formation selectivity of 95.2% and a methyl methacrylate formation activity of 5.520 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.2 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Table 4 presents the physical properties of the catalysts for the production of esters of carboxylic acids of examples 17-23.

Table 4 No. Catalyst The compositions of silicon oxide and aluminum oxide (mol.%) The applied amount of Ni and Au (wt.%) The ratio of the constituent elements of the catalyst (atomic ratios) Si Al Ni Au Ni / (Ni + Au) Ni / Al Ni / base metal Example 17 NiOAu / SiO ₂ -Al ₂ O ₃ 90.0 10.0 1.43 1.45 0.768 0.144 - Example 18 NiOAu / SiO ₂ -Al ₂ O ₃ 85.0 15.0 0.25 1.43 0.370 0.017 - Example 19 NiOAu / SiO ₂ -Al ₂ O ₃ 95.0 5,0 4,50 1.44 0.913 0.914 - Example 20 NiOAu / SiO ₂ -Al ₂ O ₃ 70.0 30,0 1.40 1.42 0.768 0,046 - Example 21 NiOAu / SiO ₂ -Al ₂ O ₃ -Rb ₂ O 88.5 11.5 0.97 0.95 0.774 0,110 0.137 Example 22 NiOAu / SiO ₂ -Al ₂ O ₃ -SrO 88.5 11.5 3.98 0.97 0.932 0.421 0.398 Example 23 NiOAu / SiO ₂ -Al ₂ O ₃ -MgO-La ₂ O ₃ 95.2 4.8 0.25 1,02 0.451 0,064 0,061

Example 24

The ethyl acrylate formation reaction was carried out using the same procedure and the same reaction conditions as in (3) of Example 17, except for using the catalyst obtained in (2) of Example 17 (NiOAu / SiO ₂ -Al ₂ O ₃ ), participation in the reaction of acrolein instead of methacrolein and participation in the reaction of ethanol instead of methanol.

As a result, the conversion rate of acrolein after completion of the reaction for 200 hours was 71.2%, the selectivity for the formation of ethyl acrylate was 96.2%, and the activity for the formation of ethyl acrylate per unit mass of the catalyst was 8.942 mol / h / kg of catalyst. Reactivity after 500 hours was assessed as not substantially changed and provided an acrolein conversion of 71.5%, an ethyl acrylate formation selectivity of 96.1% and an ethyl acrylate formation activity of 8.970 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.4 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 25

(1) Receiving media

An aqueous solution in which 3.75 kg of aluminum nitrate nonahydrate, 2.56 kg of magnesium nitrate and 540 g of 60% nitric acid was dissolved in 5.0 L of pure water was gradually added with stirring to 20.0 kg of a silica sol solution. with colloidal particles with a diameter of 10 to 20 nm, maintained at 15 ° C (Snowtex N-30 manufactured by Nissan Chemical Industries, Ltd. (SiO ₂ content: 30 wt.%)), obtaining a mixed suspension of silica sol, aluminum nitrate and nitrate magnesium. Thereafter, the mixed suspension was aged by aging at 50 ° C. for 24 hours. After cooling to room temperature, the mixed suspension was spray dried in a spray drying apparatus with a set gas outlet temperature of 130 ° C to obtain a solid material.

The obtained solid-state material was placed in a layer about 1 cm thick in an open-top stainless steel container, after which it was heated in an electric furnace from room temperature to 300 ° C for 2 hours, and then kept at this temperature for 3 hours. After additional heating to 600 ° C for 2 hours, followed by keeping it at this temperature for 3 hours, the solid-state material was gradually cooled to obtain a carrier. The amounts of silicon, aluminum and magnesium in the resulting carrier were 83.3 mol%, 8.3 mol% and 8.3 mol%, respectively, based on the total molar amount of silicon, aluminum and magnesium. The specific surface, as determined by nitrogen adsorption, was 148 m ² / g, the pore volume was 0.26 ml / g, and the average pore diameter was 8 nm. The average particle diameter of the carrier, in accordance with the results of measurements by the particle size analyzer by laser diffraction, was 64 μm. In addition, it was found that the shape of the carrier is close to spherical, based on visual studies using a scanning electron microscope (SEM).

(2) Preparation of catalyst

1.0 l of a solution containing 23.78 g of nickel nitrate hexahydrate and 19 ml of a 1.3 mol / L aqueous solution of hydrochloric acid was heated to 90 ° C. 300 g of the support based on the silica-alumina-magnesium oxide system obtained above were placed in this aqueous solution and kept at 90 ° C with stirring, then stirring was continued for 1 hour, precipitating the nickel and gold components on the support.

Then, after keeping in a calm state, the supernatant was removed and the precipitate was washed several times with distilled water, the liquid was filtered. After drying the filtrate for 16 hours at 105 ° C, the product was calcined for 3 hours at 500 ° C in air, obtaining a catalyst coated with 1.52 wt.% Nickel and 1.49 wt.% Gold (NiOAu / SiO ₂ -Al ₂ O ₃ —MgO). The atomic ratio Ni / (Ni + Au) in the obtained catalyst was 0.774, the atomic ratio Ni / Al was 0.179, and the atomic ratio Ni / Mg was 0.179. The specific surface, as determined by nitrogen adsorption, was 150 m ² / g, the pore volume was 0.28 ml / g, and the average pore diameter was 5 nm.

The average particle diameter of the catalyst, in accordance with the measurement results of the particle size analyzer by laser diffraction, was 65 μm. It was found that the shape of the catalyst is close to spherical, based on visual studies using a scanning electron microscope (SEM).

According to the results of powder X-ray diffraction (XRD), a diffraction pattern corresponding to nickel was not observed, and it was confirmed that nickel is present in an amorphous state. On the other hand, although it could not be defined as a pronounced peak, there was a wide peak corresponding to gold crystals. Although the magnitude of this peak was close to the detection limit of powder X-ray diffraction (2 nm), calculations of the average crystallite size using the Scherrer formula gave a value of about 3 nm.

With respect to the chemical state of Ni, a valency of 2 was confirmed based on the results of X-ray photoelectron spectroscopy (XPS). Moreover, the chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the high resolution X-ray luminescence (HRXRF), and was defined as a chemical state different from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα- spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.489 and the chemical shift (ΔE) was 0.340. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm (number average particle diameter: 3.0 nm) were deposited on the carrier. A visual study of enlarged images of nanoparticles showed that the nanoparticles had a lattice structure corresponding to the lattice period of Au (111). Point analysis of the composition by STEM-EDS for each nanoparticle confirmed that gold and nickel were contained in each nanoparticle. The average ratio of nickel and gold atoms in composite nanoparticles (the number of nanoparticles used in the calculation: 50) was 0.85. Moreover, in the analysis of the nano-regions of the observed particles, nickel was distributed over gold in all particles, and more nickel was found at the edges of all particles.

Further, according to the results of studying changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), the absorption peaks of surface plasmons due to gold nanoparticles were not observed near 530 nm, while a wide absorption region was observed. characteristic for NiO ₂ over a wavelength range of 200 to 800 nm.

Based on these results, it was found that the nanoparticles contained in the catalyst according to this embodiment have a shape in which the surface of the gold nanoparticles is coated with oxidized nickel and have a surface electronic state different from that for gold nanoparticles containing a single metal component.

(3) Synthesis of carboxylic acid ester

The reaction was carried out in the same manner as in (3) of Example 17, using the catalyst prepared above (NiOAu / SiO ₂ —Al ₂ O ₃ —MgO). As a result, the conversion of methacrolein after completion of the reaction for 200 hours was 65.3%, the selectivity for the formation of methyl methacrylate was 96.1%, and the activity of the formation of methyl methacrylate per unit mass of the catalyst was 8.192 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not significantly changed and provided a methacrolein conversion of 65.1%, a methyl methacrylate formation selectivity of 96.0% and a methyl methacrylate formation activity of 8.159 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases, thereby confirming that peeling and leaching of nickel and gold, which are active components of the catalyst, as well as leaching of silicon oxide, which is a component of the carrier, were suppressed. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the pore volume of the catalyst, as determined by nitrogen adsorption, was 0.27 ml / g, and the average pore diameter was 5 nm. In addition, a visual study of the catalyst after the reaction using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the support (number average particle diameter: 3.2 nm). Point-by-point analysis by STEM-EDS for each nanoparticle confirmed that nickel and gold were contained in each nanoparticle. The average ratio of nickel and gold atoms in composite nanoparticles (the number of nanoparticles used in the calculation: 50) was 0.82. Moreover, in the analysis of the nano-regions of the observed particles, nickel was distributed over gold in all particles, and more nickel was found at the edges of all particles. In addition, according to the results of studying changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), the absorption peaks of surface plasmons due to gold nanoparticles were not observed near 530 nm.

Based on these results, it was confirmed that the physical properties of the catalyst and the structure of the nanoparticles of this embodiment did not change after the reaction compared to the initial state.

Example 26

A support having a specific surface area of 155 m ² / g was obtained in the same manner as in (1) of Example 25, except that aluminum nitrate and magnesium nitrate were added to the silica sol so that the amounts of aluminum and magnesium contained in the carrier were 13.6 mol% and 4.3 mol%, respectively, based on the total molar amount of silicon, aluminum and magnesium, and a calcination temperature of 700 ° C was set.

Then, the catalyst was obtained in the same manner as in (2) of Example 25, except for the use of the above support and the use of nickel nitrate hexahydrate in an amount of 3.72 g.

The applied amounts of nickel and gold in the resulting catalyst were 0.20 wt.% And 1.48 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.312, and the atomic ratio of Ni / Al was 0.014, while the atomic ratio of Ni / Mg was 0.046. According to the results of powder X-ray diffraction (XRD), a diffraction pattern corresponding to nickel was not observed, thus confirming that nickel is present in an amorphous state. There was a peak, although broad, as described above, corresponding to gold crystals, and the average crystallite size was 3.0 nm in accordance with the calculations.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.480, and the chemical shift (ΔE) was 0.334. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were deposited on the carrier (number average particle diameter: 3.3 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX) and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.79.

In addition, according to the results of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17 using this catalyst. As a result, the conversion rate of methacrolein after completion of the reaction for 200 hours was 64.4%, the selectivity for the formation of methyl methacrylate was 95.8%, and the activity of the formation of methyl methacrylate per unit mass of the catalyst was 8.054 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 64.6%, a methyl methacrylate formation selectivity of 95.7%, and a methacrylate formation activity of 8.071 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.4 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 27

A support having a specific surface area of 138 m ² / g was obtained in the same manner as in (1) of Example 25, except that aluminum nitrate and magnesium nitrate were added to the silica sol so that the amounts of aluminum and magnesium contained in the carrier were 22.3 mol% and 5.6 mol%, respectively, based on the total molar amount of silicon, aluminum and magnesium, and a calcination temperature of 800 ° C was set.

Then, the catalyst was obtained in the same manner as in (2) of Example 25, except for the use of the above support and the use of nickel nitrate hexahydrate in an amount of 77.29 g.

The applied amounts of nickel and gold in the resulting catalyst were 5.0 wt.% And 1.49 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.918, and the atomic ratio of Ni / Al was 0.217, while the atomic ratio of Ni / Mg was 0.858.

According to the results of powder x-ray diffraction (XRD) there was a wide peak corresponding to gold crystals. The average crystallite size calculated by Scherrer’s formula was approximately 3.0 nm. On the other hand, a diffraction pattern due to nickel was not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.479 and the chemical shift (ΔE) was 0.327. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 3.1 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.93.

In addition, according to the results of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17 using this catalyst. As a result, the methacrolein conversion rate after the reaction for 200 hours was 64.1%, the methyl methacrylate formation selectivity was 95.6%, and the methyl methacrylate formation activity per unit mass of the catalyst was 8.0 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 63.9%, a methyl methacrylate formation selectivity of 95.7%, and a methacrylate formation activity of 7.983 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.2 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 28

A support having a specific surface area of 123 m ² / g was obtained in the same manner as in (1) of Example 25, except that aluminum nitrate and magnesium nitrate were added to the silica sol so that the amounts of aluminum and magnesium contained in the carrier were 36.6 mol% and 17.2 mol%, respectively, based on the total molar amount of silicon, aluminum and magnesium, and a calcination temperature of 800 ° C was set.

The catalyst was then prepared in the same manner as in (2) of Example 25, except for the use of the above support, the use of nickel nitrate hexahydrate in an amount of 16.35 g and the use of 13 ml of a 1.3 mol / L aqueous solution of hydrochloric acid.

The applied amounts of nickel and gold in the resulting catalyst were 1.0 wt.% And 0.90 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.789, and the atomic ratio of Ni / Al was 0.025, while the atomic ratio of Ni / Mg was 0.053.

Based on the results of X-ray powder diffraction (XRD), there was a broad peak corresponding to gold crystals. The average crystallite size calculated by Scherrer’s formula was approximately 3 nm. On the other hand, a diffraction pattern due to nickel was not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.487, and the chemical shift (ΔE) was 0.344. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 2.8 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 1.03.

In addition, according to the results of a study of changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of example 17, except for the use of this catalyst and the use of an amount of catalyst of 240 g. As a result, the conversion of methacrolein after completion of the reaction for 200 hours was 63.4%, the selectivity for the formation of methyl methacrylate was 95 , 3%, and the activity of the formation of methyl methacrylate per unit mass of the catalyst was 6.573 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 63.6%, a methyl methacrylate formation selectivity of 95.4% and a methyl methacrylate formation activity of 6.601 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.0 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 29

Sulfuric acid was added to 10 kg of sodium silicate solution No. 3 (SiO ₂ : from 28 to 30 wt.%, Na ₂ O: from 9 to 10 wt.%) To bring the pH to 9, after which Al ₂ (SO ₄ ) ₃ to bring the pH to 2. In addition, sodium aluminate was then added to bring the pH to 5-5.5, after which it was partially dehydrated to obtain a hydrogel containing about 10 wt.% Silica-alumina. After spray drying with a spray drying device at 130 ° C., the hydrogel was washed until the Na ₂ O content was 0.02 wt.% And the SO ₄ content was 0.5 wt.% Or less. Then it was mixed with 300 g of MgO in the form of a suspension, subjected to heat treatment for 3 hours at 80 ° C, filtered and washed, after which it was dried for 6 hours at 110 ° C, heated for 3 hours to 700 ° C, kept at this temperature for 3 hours and then gradually cooled. The resulting carrier contained 79.1 mol%, 14.7 mol% and 6.3 mol% of silicon, aluminum and magnesium, respectively, based on the total molar amount of silicon, aluminum and magnesium. The specific surface, as determined by nitrogen adsorption, was 223 m ² / g. The average particle diameter of the carrier was 60 μm, in accordance with the results obtained by the laser diffraction particle size analyzer. Based on visual studies using a scanning electron microscope (SEM), it was found that the shape of the carrier was almost spherical.

The catalyst was then prepared in the same manner as in (2) of Example 25, except for the use of the above support, the use of nickel nitrate hexahydrate in an amount of 47.56 g, and the use of 13 ml of an aqueous solution of 1.3 mol / L hydrochloric acid.

The applied amounts of nickel and gold in the resulting catalyst were 3.02 wt.% And 0.95 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.914, and the atomic ratio of Ni / Al was 0.202, while the atomic ratio of Ni / Mg was 0.471.

In accordance with the results of powder x-ray diffraction (XRD) there was a wide peak corresponding to gold crystals. The average crystallite size calculated by Scherrer’s formula was approximately 3 nm. On the other hand, a diffraction pattern due to nickel was not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin

divalent nickel, as suggested on the basis of high resolution X-ray luminescence (HRXRF), and was defined as a chemical state that is different from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.490, and the chemical shift (ΔE) was 0.336. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 2.9 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX) and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 1.12.

In addition, according to the results of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17, except for the use of this catalyst and the use of an amount of catalyst of 240 g. As a result, the conversion of methacrolein after completion of the reaction for 200 hours was 66.2%, the selectivity for the formation of methyl methacrylate was 95 , 8%, and the activity of the formation of methyl methacrylate per unit mass of the catalyst was 6.899 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 66.1%, a methyl methacrylate formation selectivity of 95.9% and a methyl methacrylate formation activity of 6.896 mol / h / kg of catalyst.

In addition, when the concentrations of Ni, Au and Si ions in the reaction solution were analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm or less in both cases, and the concentration Si was 1 ppm or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.0 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 30

A carrier having a specific surface area of 167 m ² / g was obtained in the same manner as in (1) of Example 25, except that aluminum nitrate and magnesium hydroxide were added to the silica sol so that the amounts of aluminum and magnesium contained in the carrier were 10.2 mol% and 7.2 mol%, respectively, based on the total molar amount of silicon, aluminum and magnesium, and a calcination temperature of 600 ° C was set.

The catalyst was then prepared in the same manner as in (2) of Example 25, except for the use of the above support, use of nickel nitrate hexahydrate in an amount of 112.97 g, and use of 38 ml of a 1.3 mol / L aqueous solution of hydrochloric acid.

The applied amounts of nickel and gold in the resulting catalyst were 7.50 wt.% And 3.10 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.89, and the atomic ratio of Ni / Al was 0.724, while the atomic ratio of Ni / Mg was 1.0.

In accordance with the results of powder x-ray diffraction (XRD) there was a wide peak corresponding to gold crystals. The average crystallite size calculated according to the Scherrer formula was approximately 5 nm. On the other hand, a diffraction pattern due to nickel was not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.487, and the chemical shift (ΔE) was 0.333. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 4 to 5 nm (number average particle diameter: 4.2 nm) were deposited on the carrier. Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.71.

In addition, according to the results of a study of changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17, except for using this catalyst and using an amount of catalyst of 100 g. As a result, the conversion of methacrolein after completion of the reaction for 200 hours was 63.4%, the selectivity for the formation of methyl methacrylate was 95 , 2%, and the activity of the formation of methyl methacrylate per unit mass of the catalyst was 15.759 mol / h / kg of catalyst. Reactivity after 500 hours was assessed as not substantially changed and provided a methacrolein conversion of 63.2%, a methyl methacrylate formation selectivity of 94.9% and a methyl methacrylate formation activity of 15.66 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm. or less in both cases, and the Si concentration was 1 ppm. or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 4.2 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 31

A support having a specific surface area of 134 m ² / g was obtained in the same manner as in (1) of Example 25, except that aluminum nitrate and magnesium hydroxide were added to the silica sol so that the amounts of aluminum and magnesium contained in the carrier were 15.1 mol% and 37.5 mol%, respectively, based on the total molar amount of silicon, aluminum and magnesium, and a calcination temperature of 600 ° C. was set.

The catalyst was then prepared in the same manner as in (2) of Example 25, except for the use of the above support, the use of nickel nitrate hexahydrate in an amount of 46.0 g, and the use of 38 ml of a 1.3 mol / L aqueous solution of hydrochloric acid.

The applied amounts of nickel and gold in the resulting catalyst were 3.0 wt.% And 2.99 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.771, and the atomic ratio of Ni / Al was 0.174, while the atomic ratio of Ni / Mg was 0.07.

In accordance with the results of powder x-ray diffraction (XRD) there was a wide peak corresponding to gold crystals. The average crystallite size calculated according to the Scherrer formula was approximately 5 nm. On the other hand, a diffraction pattern due to nickel was not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.488 and the chemical shift (ΔE) was 0.334. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle size distribution of 4 to 6 nm (number average particle diameter: 5.2 nm) were deposited on the carrier. Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.65.

In addition, according to the results of a study of changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17, except for using this catalyst and using an amount of catalyst of 100 g. As a result, the conversion of methacrolein after completion of the reaction for 200 hours was 61.3%, the selectivity for the formation of methyl methacrylate was 95 , 4%, and the activity of the formation of methyl methacrylate per unit mass of the catalyst was 15.269 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 61.2%, a methyl methacrylate formation selectivity of 95.6% and a methyl methacrylate formation activity of 15.276 mol / h / kg of catalyst.

In addition, when the concentrations of Ni, Au and Si ions in the reaction solution were analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm or less in both cases, and the concentration Si was 1 ppm or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 5.1 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 32

A support having a specific surface area of 144 m ² / g was obtained in the same manner as in (1) of Example 25, except that aluminum nitrate and magnesium nitrate were added to the silica sol so that the amounts of aluminum and magnesium contained in the carrier, amounted to 5.6 mol.% and 4.4 mol.%, respectively, based on the total molar amount of silicon, aluminum and magnesium.

The catalyst was then prepared in the same manner as in (2) of Example 25, except for the use of the above support, the use of nickel nitrate hexahydrate in an amount of 5.94 g, and the use of 12 ml of an aqueous solution of 1.3 mol / L hydrochloric acid.

The applied amounts of nickel and gold in the resulting catalyst were 0.30 wt.% And 0.90 wt.%, Respectively. In addition, the atomic ratio of Ni / (Ni + Au) was 0.528, and the atomic ratio of Ni / Al was 0.053, while the atomic ratio of Ni / Mg was 0.069.

According to the results of powder x-ray diffraction (XRD) there was a wide peak corresponding to gold crystals. The average crystallite size calculated by Scherrer’s formula was approximately 3 nm. On the other hand, a diffraction pattern due to nickel was not observed, thus confirming that nickel is present in an amorphous state.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.411, and the chemical shift (ΔE) was 0.331. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 2.8 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 1.15.

In addition, according to the results of a study of changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17, except for the use of this catalyst and the use of an amount of catalyst of 240 g. As a result, the conversion of methacrolein after completion of the reaction for 200 hours was 62.1%, the selectivity of methyl methacrylate formation was 95 , 2%, and the activity of the formation of methyl methacrylate per unit mass of the catalyst was 6.432 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a methacrolein conversion of 62.3%, a methyl methacrylate formation selectivity of 95.1% and a methyl methacrylate formation activity of 6.445 mol / h / kg of catalyst.

In addition, when the concentrations of Ni, Au and Si ions in the reaction solution were analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm or less in both cases, and the concentration Si was 1 ppm or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.0 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Table 5 presents the physical properties of the catalysts for the production of carboxylic acid esters of Examples 25-32.

Table 5 No. Catalyst The elemental composition of the carrier (mol.%) The applied amount of Ni and Au (wt.%) The ratio of the constituent elements of the catalyst (atomic ratios) Si Al Mg Ni Au Ni / (Ni + Au) Ni / Al Ni / Mg Example 25 NiOAu / SiO ₂ -Al ₂ O ₃ -MgO 83.3 8.3 8.3 1,52 1.49 0.774 0.179 0.179 Example 26 NiOAu / SiO ₂ -Al ₂ O ₃ -MgO 82.0 13.6 4.3 0.20 1.48 0.312 0.014 0,046 Example 27 NiOAu / SiO ₂ -Al ₂ O ₃ -MgO 72.0 22.3 5,6 5.00 1.49 0.918 0.217 0.858 Example 28 NiOAu / SiO ₂ -Al ₂ O ₃ -MgO 46.2 36.6 17,2 1.00 0.90 0.789 0,025 0,053 Example 29 NiOAu / SiO ₂ -Al ₂ O ₃ -MgO 79.1 14.7 6.3 3.02 0.95 0.914 0.202 0.471 Example 30 NiOAu / SiO ₂ -Al ₂ O ₃ -MgO 82.6 10,2 7.2 7.50 3.10 0.890 0.724 1,030 Example 31 NiOAu / SiO ₂ -Al ₂ O ₃ -MgO 47.4 15.1 37.5 3.00 2.99 0.771 0.174 0,070 Example 32 NiOAu / SiO ₂ -Al ₂ O ₃ -MgO 90.0 5,6 4.4 0.30 0.90 0.528 0,053 0,069

Example 33

The ethyl acrylate formation reaction was carried out using the same procedure and the same reaction conditions as in (3) of Example 17, except for the participation of the catalyst obtained in Example 25 (NiOAu / SiO ₂ -Al ₂ O ₃ -MgO) in the reaction acrolein instead of methacrolein and participation in the reaction of ethanol instead of methanol.

As a result, the conversion rate of acrolein after completion of the reaction for 200 hours was 75.4%, the selectivity for the formation of ethyl acrylate was 97.3%, and the activity of the formation of ethyl acrylate per unit mass of the catalyst was 9.577 mol / h / kg of catalyst. Reactivity after 500 hours was assessed as not substantially changed and provided an acrolein conversion of 75.2%, an ethyl acrylate formation selectivity of 97.4%, and an ethyl acrylate formation activity of 9.562 mol / h / kg of catalyst.

In addition, when the concentrations of Ni, Au and Si ions in the reaction solution were analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm or less in both cases, and the concentration Si was 1 ppm or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.1 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 34

The methylglycolate formation reaction was carried out using the same procedure and the same reaction conditions as in (3) of Example 17, except for the use of the catalyst obtained in Example 25 (NiOAu / SiO ₂ -Al ₂ O ₃ -MgO) and participation in ethylene glycol reactions instead of methacrolein.

As a result, the conversion of ethylene glycol after the reaction for 200 hours was 52.4%, the selectivity for the formation of methyl glycolate was 92.4%, and the activity of the formation of methyl glycolate per unit mass of the catalyst was 6.321 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as not substantially changed and provided a conversion of ethylene glycol of 52.6%, a selectivity of methyl glycolate formation of 92.3%, and a methyl glycolate formation activity of 6.33 mol / h / kg of catalyst.

In addition, when the concentrations of Ni, Au and Si ions in the reaction solution were analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the concentrations of Ni and Au were 0.1 ppm or less in both cases, and the concentration Si was 1 ppm or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 3.2 nm, thereby showing the practical absence of any changes after the reaction compared to the initial state.

Example 35

A catalyst coated with 1.45 wt.% Nickel and 1.44 wt.% Gold (NiOAu / SiO ₂ / K) was obtained in the same manner as in (2) of Example 17, except that a support was used in which commercially available silica (CARiACT Q-10, Fuji Silysia Chemical, Ltd.) was impregnated with 4 wt.% potassium and calcined at 600 ° C. The atomic ratio Ni / (Ni + Au) in the resulting catalyst was 0.772. Based on the results of a powder X-ray diffraction (XRD) study of this catalyst, a diffraction pattern corresponding to nickel was not observed, thereby confirming that nickel is present in an amorphous state. On the other hand, there was a broad peak corresponding to gold crystals, and the average crystallite size calculated by the Scherrer formula was about 3 nm.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and the Ni Kα spectrum closely matches the spectrum of nickel oxide, which is the only compound. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 0.325 and the chemical shift (ΔE) was 0.331. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 3.2 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.86.

In addition, according to the results of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17 using this catalyst. As a result, the conversion rate of methacrolein after the reaction for 200 hours was 45.2%, the selectivity for the formation of methyl methacrylate was 92.5%, and the activity for the formation of methyl methacrylate per unit mass of the catalyst was 5.458 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as showing a decrease in reactivity and selectivity, which led to a methacrolein conversion of 40.4%, methyl methacrylate formation selectivity of 91.4%, and methyl methacrylate formation activity of 4.821 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the Ni concentration was 5 ppm and 3 ppm, the Au concentration was 1 h ./mln and 0.6 ppm, and Si concentrations were 10 ppm and 7 ppm, thus demonstrating the peeling and leaching of Ni, Au and Si. When the catalyst was recovered after undergoing a reaction for 500 hours and examined using a scanning electron microscope (SEM), cracking and chipping were observed in the portion of the catalyst.

In addition, the number average particle diameter of the composite nanoparticles, as determined by a transmission electron microscope (TEM), was 4.6 nm, thereby indicating that sintering of the composite nanoparticles took place.

Example 36

A catalyst coated with 1.49 wt.% Nickel and 1.51 wt.% Gold (NiOAu / γAl ₂ O ₃ ) was obtained in the same manner as in (2) of example 17, except for the use of commercially available γ-alumina ( Neobead, Mizusawa Industrial Chemicals, Ltd). The atomic ratio of Ni / (Ni + Au) in the resulting catalyst was 0.768. Based on the results of a powder X-ray diffraction (XRD) study of this catalyst, a diffraction pattern corresponding to nickel was not observed, thus confirming that nickel is present in an amorphous state. On the other hand, there was a wide peak corresponding to gold crystals, and the average crystallite size calculated by Scherrer’s formula was about 3 nm.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and was defined as a chemical state that differs from the chemical state of nickel oxide, which is the only compound, based on differences in Ni Kα spectra. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.350, and the chemical shift (ΔE) was 0.334. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 3.1 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX) and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.89.

In addition, as a result of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17 using this catalyst. As a result, the conversion rate of methacrolein after completion of the reaction for 200 hours was 47.2%, the selectivity for the formation of methyl methacrylate was 92.8%, and the activity for the formation of methyl methacrylate per unit mass of the catalyst was 5.718 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as exhibiting a decrease in reactivity and selectivity, resulting in a methacrolein conversion of 41.4%, methyl methacrylate formation selectivity of 91.5%, and a methacrylate formation activity of 4.945 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Al ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the Ni concentration was 3 ppm and 2 ppm, the Au concentration was 0, 9 ppm and 0.7 ppm, and Al concentrations were 10 ppm and 8 ppm, thus demonstrating peeling and leaching of Ni, Au, and Al. When the catalyst was recovered after undergoing a reaction for 500 hours and examined using a scanning electron microscope (SEM), cracking and chipping were observed in the portion of the catalyst. In addition, the number average particle diameter of the composite nanoparticles, as determined using a transmission electron microscope (TEM), was 4.2 nm, thereby indicating that sintering of the composite nanoparticles takes place.

Example 37

A catalyst supported by 1.50 wt.% Nickel and 1.52 wt.% Gold (NiOAu / SiO ₂ -TiO ₂ ) was obtained in the same manner as in (2) of Example 17, except that the composition used for the support silicon oxide-titanium dioxide used as a carrier in example 5. The atomic ratio of Ni / (Ni + Au) in the resulting catalyst was 0.768. Based on the results of a powder X-ray diffraction (XRD) study of this catalyst, a diffraction pattern corresponding to nickel was not observed, thus confirming that nickel is present in an amorphous state. On the other hand, there was a broad peak corresponding to gold crystals, and the average crystallite size calculated by the Scherrer formula was about 3 nm.

The chemical state of nickel corresponds to high-spin divalent nickel, as suggested by the results of high-resolution X-ray luminescence (HRXRF), and the Ni Kα spectrum closely matches the spectrum of nickel oxide, which is the only compound. The full width at half height (FWHM) of the Ni Kα spectrum of the catalyst, as obtained from the measured spectrum, was 3.252, and the chemical shift (ΔE) was 0.330. The full width at half height (FWHM) of the Ni Kα spectrum of nickel oxide, measured as a standard substance, was 3.249, and the chemical shift (ΔE) was 0.344.

In addition, a visual study of the shape of the active components of the catalyst using a transmission electron microscope (TEM / STEM) confirmed that nanoparticles with a maximum particle diameter distribution of 2 to 3 nm were applied to the carrier (number average particle diameter: 3.2 nm). Elemental analysis (20 points) was performed for each of the observed nanoparticles using an auxiliary energy dispersive X-ray detector (EDX), and the content of nickel and gold in all particles was confirmed. The atomic ratio of nickel to gold in these composite particles (average value) was 0.81.

In addition, according to the results of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), absorption peaks of surface plasmons due to gold nanoparticles were not observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17 using this catalyst. As a result, the conversion rate of methacrolein after completion of the reaction for 200 hours was 55.3%, the selectivity for the formation of methyl methacrylate was 92.8%, and the activity for the formation of methyl methacrylate per unit mass of the catalyst was 6.699 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as showing a decrease in reactivity and selectivity, which led to a conversion of methacrolein of 48.8%, a selectivity of methyl methacrylate formation of 92.1% and a methyl methacrylate formation activity of 5.867 mol / h / kg of catalyst.

In addition, when the concentration of Ni, Au and Si ions in the reaction solution was analyzed using ICP-MS 200 and 500 hours after the start of the reaction, the Ni concentration was 8.0 ppm and 3.0 ppm, concentration Au was 1.3 ppm and 0.9 ppm, and Si concentrations were 8.0 ppm and 6.0 ppm, thus demonstrating the peeling and leaching of Ni, Au and Si. When the catalyst was recovered after undergoing a reaction for 500 hours and examined by a scanning electron microscope (SEM), cracking and chipping were observed in a portion of the catalyst. In addition, the pore volume of the catalyst, as determined by nitrogen adsorption, was 0.46 ml / g, and the average pore diameter was 15 nm. The number average particle diameter of the composite nanoparticles, as determined by a transmission electron microscope (TEM), was 4.4 nm, thus showing that the pore diameter of the catalyst was increased and sintering of the composite nanoparticles took place.

Reference Example 10

A gold-coated catalyst in an amount of 1.48 wt.% (Au / SiO ₂ -Al ₂ O ₃ ) was obtained in the same manner as in (2) of Example 17, except that an oxide-based support was used for the support silica-alumina obtained in (1) of Example 17, and nickel nitrate hexahydrate was not added. According to the results of powder X-ray diffraction (XRD) for this catalyst, there was a wide peak corresponding to gold crystals. The average crystallite size calculated by the Scherrer formula was approximately 3 nm. When the shape of the gold particles was observed using a transmission electron microscope (TEM), it was confirmed that gold particles having a number average particle diameter of 3.5 nm were deposited on the carrier. In addition, the specific surface area of the catalyst was 148 m ² / g, the pore volume of the catalyst, as determined by nitrogen adsorption, was 0.29 ml / g, and the average pore diameter was 8 nm. In addition, as a result of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), a peak of absorption of surface plasmons due to gold nanoparticles (at about 530 nm) was observed.

The reaction was carried out in the same manner as in (3) of Example 17 using this catalyst. As a result, the methacrolein conversion after the reaction for 200 hours was 25.3%, the methyl methacrylate formation selectivity was 80.5%, and the methyl methacrylate formation activity per unit mass of the catalyst was 2.659 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as showing a decrease in reactivity and selectivity, which led to a methacrolein conversion of 17.8%, methyl methacrylate formation selectivity of 78.3% and methyl methacrylate formation activity of 1.819 mol / h / kg of catalyst.

In addition, when the concentrations of Au and Si ions in the reaction solution were analyzed by ICP-MS 200 and 500 hours after the start of the reaction, the Au concentrations were 0.1 ppm or less in both cases, and the Si concentration was 1 h ./mln or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the pore volume of the catalyst, as determined by nitrogen adsorption, was 0.41 ml / g, and the average pore diameter was 13 nm. The number average particle diameter of the gold nanoparticles, as determined by a transmission electron microscope (TEM), was 5.3 nm, thereby indicating that the pore diameter of the catalyst was increased and sintering of the gold nanoparticles took place.

Reference Example 11

A gold-coated catalyst in an amount of 1.48 wt.% (Au / SiO ₂ -Al ₂ O ₃ -MgO) was obtained in the same manner as in (2) of Example 25, except that a support based on a support was used silica-alumina-magnesium oxide systems prepared in (1) of Example 25 and no nickel nitrate hexahydrate was added. According to the results of powder x-ray diffraction (XRD) for this catalyst there was a wide peak corresponding to gold crystals. The average crystallite size calculated by Scherrer’s formula was approximately 3 nm. When the shape of the gold particles was examined using a transmission electron microscope (TEM), it was confirmed that gold particles with an average particle diameter of 3.4 nm were deposited on the carrier. In addition, the specific surface area of the catalyst was 152 m ² / g, the pore volume of the catalyst, as determined by nitrogen adsorption, was 0.25 ml / g, and the average pore diameter was 5 nm. In addition, as a result of studying the changes in the electronic excited state of this catalyst by UV and visible spectroscopy (UV-Vis), a peak in the absorption of surface plasmons caused by gold nanoparticles was observed (at about 530 nm).

The reaction was carried out in the same manner as in (3) of Example 17 using this catalyst. As a result, the conversion of methacrolein after the reaction for 200 hours was 29.3%, the selectivity for the formation of methyl methacrylate was 82.3%, and the activity of formation of methyl methacrylate per unit mass of the catalyst was 3.148 mol / h / kg of catalyst. Reactivity after 500 hours was evaluated as showing a decrease in reactivity and selectivity, which led to a methacrolein conversion of 23.5%, methyl methacrylate formation selectivity of 80.1%, and methyl methacrylate formation activity of 2.457 mol / h / kg of catalyst.

In addition, when the concentrations of Au and Si ions in the reaction solution were analyzed by ICP-MS 200 and 500 hours after the start of the reaction, the Au concentrations were 0.1 ppm or less in both cases, and the Si concentration was 1 h ./mln or less in both cases. When the catalyst was recovered after the reaction for 500 hours and examined using a scanning electron microscope (SEM), no significant cracking or chipping of the catalyst particles was observed. In addition, the pore volume of the catalyst, as determined by nitrogen adsorption, was 0.37 ml / g, and the average pore diameter was 10 nm. The number average particle diameter of the gold nanoparticles, as determined by a transmission electron microscope (TEM), was 5.4 nm, and an enlarged pore diameter of the catalyst and sintering of the gold nanoparticles were observed.

Based on the results described above, the catalyst for producing carboxylic acid ester in accordance with this embodiment provides an efficient way to obtain carboxylic acid esters with high selectivity from aldehyde and alcohol, or one or more types of alcohols, and exhibits excellent mechanical strength and chemical the resistance of the carrier without cracking or chipping of the catalyst even after a long period of time. In addition, there was practically no manifestation of peeling or leaching of nickel and component X, which are active components of the catalyst, an increase in the pore diameter of the catalyst, or sintering of composite nanoparticles, which makes it possible to maintain a high level of catalyst reactivity even after a long period of time.

This application is based on a Japanese patent application filed by the Japanese Patent Office on August 13, 2007 (Japanese Patent Application No. 2007-210962), a Japanese patent application filed by the Japanese Patent Office on October 11, 2007 (Japanese Patent Application No. 2007 -265375), a Japanese patent application filed by the Japanese Patent Office on October 26, 2007 (Japanese Patent Application No. 2007-279411) and a Japanese patent application, registered by the Japanese Patent Office April 14, 2008 (Japanese Patent Application No. 2008 -105103), the contents of which are included to this document by reference.

Industrial applicability

The present invention can be used in industry as a catalyst for producing a carboxylic acid ester by reacting an aldehyde and an alcohol, or one or more types of alcohols, in the presence of oxygen.

Claims (17)

1. A catalyst for producing a carboxylic acid ester by reacting (a) an aldehyde and an alcohol, or (b) one or more kinds of alcohols, in the presence of oxygen, containing:
oxidized nickel; and
X, where X represents at least one element selected from the group consisting of palladium, platinum, ruthenium, gold, silver and copper, deposited on a carrier in the range of the atomic ratio Ni / (Ni + X) from 0.20 to 0 , 99. 2. The catalyst according to claim 1, containing a composite nanoparticle consisting of oxidized nickel and X, where X represents at least one element selected from the group consisting of palladium, platinum, ruthenium, gold, silver and copper. 3. The catalyst according to claim 2, in which the composite nanoparticle is a particle having X in its core, and the surface of the core is coated with oxidized nickel. 4. The catalyst according to claim 2 or 3, in which, in addition to the composite nanoparticle, the carrier contains independently oxidized nickel. 5. The catalyst according to claim 1 or 2, in which the oxidized nickel is a nickel oxide and / or a complex oxide containing Nickel. 6. The catalyst according to claim 1 or 2, in which the carrier is an aluminum-containing composition based on silicon oxide, which contains silicon oxide and aluminum oxide, and the amount of aluminum is in the range from 1 to 30 mol.%, Calculated on the total molar amount of silicon and aluminum. 7. The catalyst according to claim 6, in which the carrier further comprises at least one type of main metal component selected from the group consisting of alkali metal, alkaline earth metal and rare earth metal. 8. The catalyst according to claim 6, in which the ratio of Nickel and alumina is from 0.01 to 1.0 based on the atomic ratio of Ni / Al. 9. The catalyst according to claim 7 or 8, in which the ratio of Nickel and the main metal component is from 0.01 to 1.2 based on the atomic ratio Ni / (alkali metal + alkaline earth metal + rare earth metal). 10. The catalyst according to claim 1 or 2, in which the carrier is a composition containing silicon oxide, aluminum oxide and magnesium oxide, and contains from 42 to 90 mol.% Silicon, from 5.5 to 38 mol.% Aluminum and from 4 up to 38 mol.% magnesium calculated on the total molar amount of silicon, aluminum and magnesium. 11. The catalyst of claim 10, in which the ratio of Nickel and alumina is from 0.01 to 1.0 based on the atomic ratio of Ni / Al, and the ratio of Nickel and magnesium oxide is from 0.01 to 1.2 calculated per atomic ratio of Ni / Mg. 12. The catalyst according to claim 1 or 2, in which the specific surface is from 20 to 350 m ² / g, the pore diameter with maximum repeatability is from 3 to 50 nm, the pore volume is from 0.1 to 1.0 ml / g and the particle diameter is from 10 to 200 microns. 13. A method of producing a catalyst for producing a carboxylic acid ester according to any one of claims 1 to 12, including:
a first step for preparing a catalyst precursor by precipitation of nickel and component X, where X is at least one element selected from the group consisting of palladium, platinum, ruthenium, gold, silver and copper on a support by neutralizing an acidic solution of a soluble metal salt containing nickel and X; and a second stage of nickel oxidation by heat treatment of the obtained catalyst precursor, wherein the Ni / (Ni + X) atomic ratio is from 0.20 to 0.99. 14. A method of producing a carboxylic acid ester comprising the step of reacting a catalyst according to claims 1-12 with (a) an aldehyde and an alcohol or (b) one or more kinds of alcohols in the presence of oxygen. 15. The method according to 14, in which the aldehyde is a compound selected from acrolein, methacrolein and mixtures thereof. 16. The method according to 14, in which the aldehyde is a compound selected from acrolein, methacrolein and mixtures thereof, and the alcohol is methanol. 17. The method according to 14, in which one type of alcohol is ethylene glycol, and the other type of alcohol is methanol.

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