TW202237265A - Catalyst for production of carboxylate, method for producing carboxylate, and method for producing catalyst for production of carboxylate comprising catalyst metal particles and a carrier for supporting and carrying the catalyst metal particles - Google Patents

Abstract

A catalyst for production of carboxylate is disclosed, comprising catalyst metal particles and a carrier for supporting and carrying the catalyst metal particles, wherein a bulk density of the catalyst for production of carboxylate is not less than 0.50 g/cm3 and not more than 1.50 g/cm3, and when taking the particle size distribution of the volume-based particle size distribution of the catalyst for the manufacture of the above-mentioned carboxylate as the cumulative frequency of x% as Dx, D10/D50 ≥ 0.2 and D90/D50 ≤ 2.5, and for the FWHM of the above particle size distribution being set to W, W/D50 ≤ 1.5.

Description

Catalyst for producing carboxylate, method for producing carboxylate, and method for producing catalyst for producing carboxylate

The present invention relates to a catalyst for producing carboxylate, a method for producing carboxylate and a method for producing a catalyst for producing carboxylate.

Nickel or nickel compounds are widely used as catalysts for chemical synthesis such as oxidation reactions, reduction reactions, and hydrogenation reactions. In recent years, through various modifications and improvements of nickel-based catalysts, the aerobic oxidation reaction of alcohol under the catalyst has been realized. . However, in the chemical industry, it is well known that nickel and nickel compounds are widely effective not only for the oxidation reaction of alcohol, but also for various reactions such as various oxidation reactions, reduction reactions, and hydrogenation reactions, as well as purification catalysts and photocatalysts for automobile exhaust gas.

For example, as a method for producing carboxylate, it is proposed in Patent Document 1 to use the following composite particle carrier as a catalyst. The composite particle carrier contains nickel in an oxidized state and X (X represents , palladium, platinum, ruthenium, gold, silver, and copper) composed of composite particles composed of at least one element in the group consisting of , palladium, platinum, ruthenium, gold, silver, and copper), and a carrier that supports the above-mentioned composite particles, and has a support that locally exists on the above-mentioned composite particles Floor. It is considered that this catalyst can maintain high reactivity for a long time.

Patent Document 2 describes spherical silica particles containing aluminum and magnesium and having specific surface area, pore volume, pore distribution, bulk density, abrasion resistance, average particle size, aluminum content, and magnesium content. within the specified range. According to this document, it is considered that it can be used in a wide range of applications including catalyst carriers, and can provide spherical silica-based particles with strong mechanical strength, large specific surface area, and good fluidity. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent No. 4803767 [Patent Document 2] Japanese Patent No. 4420991

[Problem to be solved by the invention]

For the production of carboxylic acid esters using the catalysts described in Patent Documents 1 and 2, catalyst activity is required to be improved and catalysts exhibiting higher conversion rates are required. The inventors of the present invention have repeatedly conducted experiments on the production of carboxylate, and found that if the catalysts described in Patent Documents 1 and 2 are used to produce carboxylate for a long period of time, the conversion rate of the raw material tends to gradually decrease. As a result of studying the reason in more detail, it can be seen that the outflow of the catalyst from the reactor and the fluidity of the catalyst affect the conversion rate of the raw material. Furthermore, although the addition rate of the raw material and the selectivity of the carboxylate can be increased by increasing the amount of air blown in when the carboxylate is produced, when the catalyst is easy to flow out of the reactor, with the air As the blowing amount increases, the influence of the catalyst outflow becomes more significant, which will also become an obstacle to the improvement of the reaction performance in this respect.

The present invention was made in view of the above-mentioned problems in the prior art, and an object of the present invention is to provide a catalyst for carboxylic acid ester production that suppresses the outflow of the catalyst and exhibits high activity. [Technical means to solve the problem]

The inventors of the present invention found that the above-mentioned problems can be solved by setting the bulk density and particle size distribution (D ₁₀ /D ₅₀ , D ₉₀ /D ₅₀ , and W/D ₅₀ ) within predetermined ranges, and completed the present invention.

That is, the present invention includes the following aspects. [1] A catalyst for producing carboxylate, comprising catalytic metal particles and a carrier carrying the catalytic metal particles, wherein the bulk density of the catalyst for producing carboxylate is not less than 0.50 g/cm ³ and 1.50 g/cm ³ or less, D ₁₀ /D ₅₀ ≧ 0.2 and D ₉₀ /D when D _x is the particle size whose cumulative frequency becomes x% in the volume-based particle size distribution of the above-mentioned carboxylic acid ester production catalyst ₅₀ ≦2.5, W/D ₅₀ ≦1.5 when the full width at half maximum of the above-mentioned particle size distribution is W. [2] The catalyst for producing carboxylate according to [1], wherein W is 100 μm or less. [3] The catalyst for producing carboxylate according to [1] or [2], wherein the catalytic metal particles are selected from the group consisting of nickel, cobalt, palladium, platinum, ruthenium, lead, gold, silver, and copper at least one of the elements. [4] The catalyst for producing carboxylate according to any one of [1] to [3], wherein the catalyst metal particles contain nickel and/or cobalt in an oxidized state and X (X represents a catalyst selected from nickel, palladium , platinum, ruthenium, gold, silver and copper at least one element in the group of composite particles). [5] The catalyst for producing carboxylate according to [4], wherein the composition ratio of nickel or cobalt to X in the composite particle is 0.1 to 10 in Ni/X atomic ratio or Co/X atomic ratio. [6] The catalyst for producing carboxylate according to [4] or [5], wherein the composite particles contain nickel or cobalt in an oxidized state, and gold. [7] The catalyst for producing carboxylate according to any one of [4] to [6], wherein the composite particles have an average particle diameter of 2 to 10 nm. [8] The catalyst for producing carboxylate according to any one of [4] to [7], wherein the supporting layer in which the composite particles are locally present exists on the surface of the catalyst for producing carboxylate The area up to 40% of the equivalent diameter of the catalyst for the production of carboxylic acid ester. [9] The catalyst for producing carboxylate according to any one of [4] to [8], wherein the above-mentioned equivalent diameter is 200 μm or less, and the supporting layer locally present on the above-mentioned composite particles is present on the surface from the above-mentioned The area from the surface of the catalyst for production of carboxylate to 30% of the equivalent diameter of the catalyst for production of carboxylate. [10] The catalyst for producing carboxylate according to any one of [4] to [9], wherein an outer layer substantially free of composite particles is provided on the outside of the supporting layer where the composite particles locally exist , and the outer layer is formed with a thickness of 0.01-15 μm. [11] The catalyst for producing carboxylate according to any one of [4] to [10], wherein the composite particle has a core containing X, and the core is covered with nickel or cobalt in an oxidized state. [12] The catalyst for producing carboxylate according to any one of [1] to [11], wherein the carrier contains silica and alumina. [13] The catalyst for producing carboxylate according to any one of [1] to [12], wherein the D ₅₀ is not less than 10 μm and not more than 200 μm. [14] A method for producing a carboxylate, comprising the step of (a) making an aldehyde and an alcohol Reaction is performed, or (b) 1 type or 2 or more types of alcohols are reacted. [15] The method for producing a carboxylic acid ester according to [14], wherein the aldehyde is acrolein and/or methacrolein. [16] The method for producing a carboxylic acid ester according to [14] or [15], wherein the aldehyde is acrolein and/or methacrolein, and the alcohol is methanol. [Effect of Invention]

According to the present invention, it is possible to provide a catalyst for carboxylic acid ester production that suppresses the outflow of the catalyst and exhibits high activity.

Hereinafter, an embodiment of the present invention (hereinafter also referred to as "the present embodiment") will be described in detail. In addition, this invention is not limited to the following this embodiment, Various changes can be implemented within the range of the summary.

[Catalyst for production of carboxylate] The catalyst for production of carboxylate according to the present embodiment comprises catalytic metal particles and a carrier carrying the above-mentioned catalytic metal particles, and the bulk density of the catalyst for production of carboxylate is 0.5 g/cm ³ to 1.5 g/cm ³ , the full width at half maximum of the particle size distribution based on the volume of the above-mentioned carboxylic acid ester production catalyst is 100 μm or less, on the volume basis of the above-mentioned carboxylic acid ester production catalyst In the particle size distribution, when the particle size whose frequency is accumulated to x% is set as D _x , D ₁₀ /D ₅₀ ≧0.2 and D ₉₀ /D ₅₀ ≦2.5, and the full width at half maximum of the volume-based particle size distribution is set to W , W/D ₅₀ ≦1.5. Since it is comprised in this way, the catalyst for carboxylic acid ester production of this embodiment suppresses the outflow of a catalyst, and expresses high activity.

In this embodiment, the bulk density of the catalyst for carboxylic acid ester production is 0.50 g/cm ³ or more and 1.50 g/cm ³ or less. Although it is considered that the aforementioned bulk density is less related to the problem of catalyst activity reduction, it is considered that by adjusting the bulk density to the above range, the catalyst is easily diffused in the reactor and the conversion rate of the raw material is improved. That is, it is considered that if the bulk density is less than the above-mentioned lower limit, the catalyst will flow out from the reactor under long-term operation, thereby reducing the amount of catalyst and thus lowering the activity. If the bulk density is greater than the above-mentioned upper limit, the catalyst will flow out. The cyclicity is low, so the chance of contact with raw materials is lost, and the activity becomes low. From this point of view, the bulk density of the catalyst for carboxylic acid ester production is preferably from 0.70 g/cm ³ to 1.30 g/cm ³ , more preferably from 0.90 g/cm ³ to 1.20 g/cm ³ . The said bulk density can be measured by the method described in the Example mentioned later. The said bulk density can be adjusted to the said range by employ|adopting the preferable manufacturing conditions etc. which are mentioned later, for example.

D ₁₀ /D ₅₀ is 0.2 or more when D _x is the particle diameter whose cumulative frequency becomes x% in the volume-based particle diameter distribution of the catalyst for carboxylic acid ester production. D ₁₀ /D ₅₀ is an index showing the extent to which particles with small particle diameters exist relative to the average particle diameter in the catalyst for production of carboxylic acid esters. The closer the value is to 1.0, the steeper the distribution on the small particle side is. In this embodiment, by making _D10 / _D50 into 0.2 or more, the fluidity|fluidity of the catalyst for carboxylate production will improve, and a high activity will be shown. From the same viewpoint, D ₁₀ /D ₅₀ is preferably 0.3 to 0.8. D ₁₀ /D ₅₀ can be measured by a laser diffraction-scattering method, and more specifically, can be measured by a method described in Examples described later. D ₁₀ /D ₅₀ can be adjusted to the above-mentioned range by, for example, adopting preferable manufacturing conditions described later.

In the present embodiment, D ₉₀ /D ₅₀ is 2.5 or more. It is an index showing the extent to which particles with large particle diameters exist relative to the average particle diameter as a catalyst for carboxylic acid ester production, and the closer the value is to 1.0, the steeper the distribution on the large particle side is. In this embodiment, by making D ₉₀ /D ₅₀ 2.5 or more, the fluidity of the catalyst for carboxylic acid ester production will improve, and a high activity will be shown. From the same viewpoint, D ₉₀ /D ₅₀ is preferably 1.4 to 2.3. D ₉₀ /D ₅₀ can be measured by a laser diffraction-scattering method, and more specifically, it can be measured by the method described in Examples described later. D ₉₀ /D ₅₀ can be adjusted to the above-mentioned range by, for example, adopting preferable manufacturing conditions described later.

W/D ₅₀ is 1.5 or less when the full width at half maximum of the volume-based particle size distribution of the catalyst for carboxylic acid ester production is W. W/D ₅₀ is an index showing how wide the half maximum width of the peak is relative to the average particle diameter in the above-mentioned particle size distribution, and the smaller the value, the steeper the distribution. In the present embodiment, by making W/D ₅₀ 1.5 or less, the fluidity of the catalyst for carboxylic acid ester production is improved while suppressing the outflow of the catalyst, thereby suppressing the outflow of the catalyst and expressing high activity. In addition, when there are a plurality of peaks in the above-mentioned particle size distribution, W about the highest peak is made to satisfy the above-mentioned relationship. From the same viewpoint, W/D ₅₀ is preferably from 0.6 to 1.3. W/D ₅₀ can be measured by a laser diffraction-scattering method, more specifically, it can be measured by the method described in the Example mentioned later. W/D ₅₀ can be adjusted to the above-mentioned range by employing, for example, preferable manufacturing conditions described later.

In this embodiment, the above-mentioned W is preferably 100 μm or less. By setting the value of W to 100 μm or less, it tends to be possible to further suppress catalyst outflow. It is considered that not only the above-mentioned bulk density but also the above-mentioned FWHM is less relevant to the problem of lowering the catalytic activity, but by adjusting the FHM to the above-mentioned range, it tends to prevent the catalyst from flowing out of the reactor. , And subsequently, the conversion rate of raw materials is increased. Furthermore, it was not previously known that the degree to which the outflow of the catalyst from the reactor affects the conversion rate of the raw material is based on the difference in the particle size distribution of the catalyst, which is a new insight. From the same viewpoint, W is more preferably from 5 μm to 95 μm, and further preferably from 10 μm to 90 μm. W can be measured by a laser diffraction-scattering method, and more specifically, it can be measured by the method described in the Example mentioned later. W can be adjusted to the above-mentioned range by employing, for example, preferable manufacturing conditions described later.

D ₅₀ in this embodiment is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm, further preferably 40 μm to 100 μm, and even more preferably 40 μm to 80 μm. By making _D50 into this range, there exists a tendency for the catalyst for carboxylate production which suppresses the outflow of a catalyst further and shows higher activity to be obtained. D ₅₀ can be measured by the laser diffraction-scattering method, more specifically, it can be measured by the method described in the Examples described later. _D50 can be adjusted to the above-mentioned range by employing, for example, preferable manufacturing conditions described later.

In this embodiment, the particle size distribution of the catalyst is preferably a single peak. The so-called particle size distribution having a single peak means that in the volume-based particle size distribution, there are no peaks other than the highest peak that do not have more than 1/5 of the highest peak.

In the present embodiment, the catalytic metal particles are not particularly limited as long as they have the function of catalyzing the reaction for producing carboxylate esters. From the viewpoint of catalytic performance, it is preferable to contain a metal particle selected from the group consisting of nickel, At least one element of the group consisting of cobalt, palladium, platinum, ruthenium, lead, and gold, silver, and copper. Also, in terms of further catalyst performance, as the catalyst metal particles, it is more preferable to contain nickel and/or cobalt and X (X represents a catalyst selected from nickel, palladium, platinum, ruthenium, gold, silver and At least one element in the group consisting of copper) composite particles, and more preferably the composite particles contain nickel or cobalt in an oxidation state, and gold.

In this embodiment, the catalyst for carboxylic acid ester production preferably has a supporting layer in which composite particles locally exist. The term "supporting layer in which composite particles locally exist" refers to a region where composite particles are concentratedly supported in the carrier. In the catalyst for the production of carboxylate according to this embodiment, it is preferable that the composite particles are selectively supported in a certain area rather than randomly loaded in the carrier. This area is called "localized area of the composite particle". The supporting layer of existence". In the catalyst for the production of carboxylate, as long as composite particles are concentrated in a certain region compared with other parts, this region is the "supporting layer where composite particles locally exist". Therefore, which region The term "carrying layer in which composite particles locally exist" can be determined by the X-ray microprobe analysis method described later or the secondary electron reflection image of a high-resolution scanning electron microscope. The supporting layer in which the composite particles exist locally is preferably present in a region from the surface of the catalyst for carboxylate production to 40% of the equivalent diameter of the catalyst for carboxylate production. When the supporting layer in which the composite particles are locally present exists in the above-mentioned region, the influence of the diffusion rate of the reactant inside the carrier decreases, and the reaction activity tends to increase.

The catalyst for producing carboxylate esters according to the present embodiment may have various sizes and various shapes on the order of μm to cm in substantial thickness or particle diameter. Specific examples of the shape of the catalyst for carboxylic acid ester production are not limited to the following, and examples include spherical, oval, cylindrical, tablet, hollow cylindrical, plate, rod, sheet, Honeycomb and other shapes. The shape can be appropriately changed according to the reaction form, and is not limited to the following. For example, in a fixed bed reaction, a hollow cylindrical shape or a honeycomb shape with less pressure loss is selected, and a spherical shape is usually selected in a liquid phase slurry suspension condition. shape.

The term "equivalent diameter" as used herein means the diameter of a spherical particle or, in the case of irregularly shaped particles, the diameter of a sphere having the same volume as the particle or a sphere having the same surface area as the particle. The method of measuring the equivalent diameter is to use the laser diffraction-scattering particle size distribution measuring device to measure D ₅₀ , and use the measured D ₅₀ as the equivalent diameter.

The thickness of the supporting layer where the composite particles locally exist is selected from an optimal range according to the thickness of the carrier, the particle size, the type of reaction, and the reaction form. Furthermore, the "equivalent diameter of the catalyst for carboxylate production" is usually the same as the "equivalent diameter of the carrier", so the "equivalent diameter of the catalyst for carboxylate production" can be determined according to the equivalent diameter of the carrier .

On the other hand, when the equivalent diameter of the catalyst for production of carboxylate is 200 μm or less, it is preferable to carry the composite particles from the surface of the catalyst for production of carboxylate to the surface of the catalyst for production of carboxylate. In the area up to 30% of the equivalent diameter of the medium. Especially in the case of liquid phase reaction, the reaction speed and the diffusion speed of the reaction substance in the pores inside the carrier will be affected. Therefore, the design of reducing the particle size of the carrier by coordinating the reaction was previously used. In this embodiment, by thinning the supporting layer where the composite particles locally exist, a highly active catalyst for carboxylate production can be obtained without reducing the particle size of the carrier. In this case, there is also an advantage that the catalyst can be easily separated by sedimentation, and can be separated using a small-capacity separator. On the other hand, if the volume of the portion of the catalyst for producing carboxylate that does not support the composite particles becomes too large, the volume unnecessary for the reaction of each reactor may become large and be wasted. Therefore, it is preferable to set the particle size of the carrier according to the form of the reaction, and to set the thickness of the supporting layer in which the required composite particles locally exist, and the thickness of the layer not supporting the composite particles.

The catalyst for producing carboxylate may have an outer layer substantially not containing composite particles outside the supporting layer in which composite particles locally exist. The outer layer is preferably formed from the outer surface of the carrier with a thickness of 0.01 to 15 μm. By setting the outer layer in this range, it can be used as an anti-contact method in the reaction using fluidized bed, bubble column, stirred reactor, etc., which is worried about the friction of catalyst particles or the reaction that may cause the accumulation of poisoning substances. It can be used as a catalyst that is poisonous and inhibits the shedding of composite particles caused by abrasion. Also, since the outer layer can be controlled to be extremely thin, a large decrease in activity can be suppressed.

The thickness of the outer layer that does not substantially contain composite particles is selected according to the reaction characteristics, physical properties of the carrier, the loading capacity of the composite particles, etc., preferably 0.01-15 μm, more preferably 0.1-10 μm, and even more Preferably, it is 0.2-5 μm. If the thickness of the outer layer (the layer not supporting the composite particles) exceeds 15 μm, the catalytic activity may decrease even though the effect of improving the life of the catalyst does not change when the composite particles are used as a catalyst. If the thickness of the outer layer is less than 0.01 μm, there is a tendency for composite particles to fall off due to abrasion.

In this embodiment, the term "substantially free of composite particles" means that in the X-ray microprobe analysis method described later or in the secondary electron reflection image of a high-resolution scanning electron microscope, there is substantially no relative intensity The peak of the distribution of nickel and/or cobalt and X (X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) in an oxidation state of more than 10%.

As the nickel in the oxidation state that can constitute the composite particle in this embodiment, nickel oxide formed by bonding nickel and oxygen (for example, Ni ₂ O, NiO, NiO ₂ , Ni ₃ O ₄ , Ni ₂ O ₃ ); or nickel-containing composite oxides such as nickel, X and/or one or more other metal elements, and nickel oxide compounds or solid solutions formed by bonding with oxygen, or mixtures thereof. In addition, as the cobalt in the oxidation state that can constitute the composite particle in this embodiment, cobalt oxide (for example, CoO, Co ₂ O ₃ , Co ₃ O ₄ ) formed by bonding cobalt and oxygen; or cobalt , X and/or one or more other metal elements, and cobalt oxide compounds or solid solutions formed by bonding with oxygen, or a mixture of these and other cobalt-containing composite oxides.

The term "nickel oxide" as used herein means a compound containing nickel and oxygen. Nickel oxides include Ni ₂ O, NiO, NiO ₂ , Ni ₃ O ₄ , Ni ₂ O ₃ or their hydrates, OOH-containing nickel hydroperoxides, or O ₂ -containing nickel as exemplified above. peroxides, or mixtures thereof.

In addition, the term "composite oxide" here means an oxide containing two or more metals. "Composite oxide" is an oxide formed by forming a compound of two or more metal oxides, including polyoxides without oxoacid ions as structural units (for example, perovskite oxides of nickel, spinel oxides, etc.) Stone-type oxides), but it is a broader concept than polyoxides, including all oxides composed of two or more metals. An oxide formed by forming a solid solution of two or more metal oxides also falls within the category of composite oxides.

Regarding the catalyst for producing carboxylate according to the present embodiment, when the composite of nickel oxide and/or cobalt oxide and X is carried out as described above, it tends to be as follows: nickel oxide having oxidative esterification activity and /or the original catalytic ability of the cobalt oxide is drawn out, showing a significantly high catalytic performance that cannot be achieved by using a catalyst comprising each single component. It is considered that it is a special effect manifested by compounding nickel oxide and/or cobalt oxide and X, and it is produced with each single component by the bifunctional effect between the two metal components or the generation of new active species, etc. A completely different new catalytic effect. Furthermore, when nickel in an oxidized state and/or cobalt in an oxidized state and X are supported on a carrier in a highly dispersed state, there is a tendency to realize epoch-making catalytic performance that cannot be obtained with conventional catalysts.

For example, if gold is selected as X, and nickel oxide and gold are highly dispersed and supported on the carrier, remarkably high catalytic performance tends to be exhibited. This catalyst for carboxylate production has a higher selectivity for carboxylate than a catalyst in which nickel oxide or gold is supported on a carrier as a single component, and the selectivity of the carboxylate is greatly increased based on a specific Ni/Au composition ratio. Tendency to increase activity. Regarding the catalytic activity of each metal atom, it shows higher activity than the particle support containing each single component, and the manifestation of the catalytic function produced by this composite is strongly dependent on the support of nickel and gold. composition. The reason for this is presumed to be that there is an optimal ratio for the formation of the oxidation state of nickel most suitable for the reaction. By carrying the two components of nickel oxide and gold dispersedly on the carrier as described above, there is a tendency to exhibit a remarkable combined effect that cannot be expected from the simple addition of the individual components.

As mentioned above, the catalyst for carboxylate production in which gold is selected as X is a carrier in which nickel and gold in an oxidized state are highly dispersed, and the two components tend to be composited at a nanometer size. When such a catalyst for carboxylate production is observed with a transmission electron microscope/scanning transmission electron microscope (TEM/STEM), roughly spherical nanoparticles of 2 to 3 nm uniformly distributed A structure dispersed on a carrier. Also, when it is used for elemental analysis of nanoparticles using energy dispersive X-ray spectroscopy (EDS), it is typically observed that nickel and gold coexist in any particle, and nickel is coated on Chennai. The morphology of the surface of the rice particles was also observed. In addition to the nanoparticles containing nickel and gold, the nickel component was also supported as a single component on the carrier. Furthermore, the existence state of the metal can be confirmed by X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (powder XRD). Typically, gold is observed as a crystalline metal. On the other hand, Nickel exists as an amorphous oxide having a divalent valence. Furthermore, if it is used for ultraviolet-visible spectroscopy (UV-Vis) that can observe changes in the excited state of electrons, it is typically observed that the gold nanoparticles derived from gold nanoparticles observed for a single metal species The surface plasmon absorption peak (about 530 nm) disappears due to the recombination of nickel oxide and gold. The disappearance of this surface plasmonic absorption peak occurs in metal oxide species other than nickel oxide (for example, metal oxides such as chromium oxide, manganese oxide, iron oxide, cobalt oxide, copper oxide, and zinc oxide) that have no effect on the reaction. Oxide) combined with gold catalyst was not observed. It is considered that the disappearance of the surface plasmon absorption peak is the result of the electronic state mixing through the contact interface between the oxidized nickel and the gold, that is, it is produced by the recombination of the two metal chemical species. Furthermore, the transition to highly oxidized nickel oxide can be confirmed by the color change of the catalyst and ultraviolet-visible spectroscopy (UV-Vis). By adding gold to nickel oxide, nickel oxide will change from gray-green to tea-brown, showing absorption across the visible region of the UV spectrum and roughly as a whole. The shape of the UV spectrum and the color of the catalyst are similar to the highly oxidized nickel peroxide (NiO ₂ ) measured as a reference sample. As described above, it is presumed that nickel oxide is transformed into nickel oxide in a highly oxidized state by the addition of gold. Based on the above results, it is considered that when gold is selected as X, the structure of the composite particle is that the gold particle is the core, and its surface is covered with nickel oxide in a high oxidation state, and gold atoms do not exist on the surface of the composite particle.

The composite particles are preferably supported on a carrier in a highly dispersed state. The composite particles are more preferably dispersed and supported in the form of fine particles or thin films, and the average particle diameter is preferably 2 to 10 nm, more preferably 2 to 8 nm, and still more preferably 2 to 6 nm. When the average particle diameter of the composite particles is within the above range, a specific active species structure containing nickel and/or cobalt and X tends to be formed, thereby improving the reactivity. Here, the average particle diameter of the composite particles in this embodiment refers to the number average particle diameter measured by a transmission electron microscope (TEM). Specifically, in an image observed with a transmission electron microscope, the black contrasting part is composite particles, and the diameter of each particle can be measured and the number average can be calculated.

The composition of nickel or cobalt and X in the composite particles is preferably in the range of 0.1 to 10, more preferably in the range of 0.2 to 8.0, and still more preferably in the range of 0.3 to 6.0 in terms of Ni/X atomic ratio or Co/X atomic ratio . If the Ni/X atomic ratio or Co/X atomic ratio is within the above range, there is a tendency to form a specific active species structure containing nickel and/or cobalt and X and the oxidation state of nickel and/or cobalt most suitable for the reaction , as a result, the activity and selectivity become higher than those outside the above range.

The form of the composite particle is not particularly limited as long as it contains two components of nickel and/or cobalt and X, but it is preferably a form in which the two components coexist in the particle and have a phase structure, such as a random chemical species. The solid solution structure occupying the lattice site of the crystal, the core-shell structure in which the various chemical species are separated in concentric spheres, the anisotropic phase separation structure in which the anisotropic phase separation exists, and the two chemical species exist adjacent to the surface of the particle Arbitrary structures of heterobondphilic structures. More preferably, it has a core containing X, and the surface of the core is coated with nickel and/or cobalt in an oxidized state. The shape of the composite particle is not particularly limited as long as it contains two components, and any shape such as a spherical shape or a hemispherical shape may be used.

As an analysis method for observing the shape of composite particles, such as the above-mentioned transmission electron microscope/scanning transmission electron microscope (TEM/STEM) is more effective, by irradiating the nanoparticle image observed by TEM/STEM Electron beams can be used to analyze the elements in the particles and draw the distribution images of the elements. It was confirmed that the composite particles in this embodiment contain nickel and/or cobalt and X in any particle as shown in Examples described later, and have a form in which the surface of X is coated with nickel and/or cobalt. In the case of such a form, depending on the position of the composition analysis point in the particle, the atomic ratio of nickel and/or cobalt to X is different, and more nickel and cobalt are detected at the edge of the particle than at the center of the particle. / or cobalt. Therefore, in each particle, the atomic ratio of nickel or cobalt to X has a range depending on the position of the analysis point, and this range is included in the range of the above-mentioned Ni/X atomic ratio or Co/X atomic ratio.

In the case of selecting gold, silver, and copper as X, ultraviolet-visible spectroscopy (UV-Vis) becomes a powerful method for specifying its structure. In gold, silver, and copper nanoparticle monomers, the photoelectric field in the visible to near-infrared region will couple with the free electrons on the surface of the metal to show surface plasmon absorption. For example, when a catalyst carrying gold particles is irradiated with visible light, an absorption spectrum derived from plasmon resonance of gold particles is observed at a wavelength of about 530 nm. However, in the catalyst for producing carboxylate carrying nickel oxide and gold of this embodiment, this surface plasmon absorption disappears, so it is considered that gold does not exist on the surface of the composite particle in this embodiment.

The solid form of nickel is not particularly limited as long as it is capable of obtaining predetermined activity, but it is preferably an amorphous form in which a diffraction peak is not observed by X-ray diffraction. By adopting such a form, it is presumed that when used as a catalyst for an oxidation reaction, the interaction with oxygen becomes higher, and further, since the bonding interface between nickel in an oxidized state and X increases, it is possible to obtain more excellent activity. tendency.

In this embodiment, X is at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper. More preferably, it is selected from nickel, palladium, ruthenium, gold, and silver.

The chemical state of X can be metal, oxide, hydroxide, a compound compound containing X and nickel, cobalt or more than one other metal element, or any of these mixtures, and the preferred chemical state is metal or oxide Object, more preferably metal. Also, the solid form of X is not particularly limited as long as it can obtain a predetermined activity, and it may be either crystalline or amorphous.

The term "other metal elements" as used herein refers to the third component element contained in the catalyst for carboxylic acid ester production other than the constituent elements of the carrier, nickel and/or cobalt in an oxidized state, and X as described later. Metal components such as alkali metals, alkaline earth metals and rare earth metals.

The catalyst for the production of carboxylate according to the present embodiment is performed by loading nickel and/or cobalt in an oxidized state and X on a carrier as described above to form composite particles containing nickel and/or cobalt in an oxidized state and X. Excellent effect. In addition, the term "composite particle" in this embodiment refers to a particle containing different binary metal species in one particle. As a different binary metal species, binary metal particles in which two components of nickel and/or cobalt and X are metals, metal particles forming an alloy or an intermetallic compound of nickel and/or cobalt and X, etc. When this is used as a catalyst for chemical synthesis, compared with the catalyst for carboxylic acid ester production of this embodiment, the selectivity of the target product and catalytic activity tend to be lower.

The catalyst for producing carboxylate according to this embodiment preferably contains nickel and/or cobalt in an oxidized state alone on a carrier in addition to the composite particles containing nickel and/or cobalt in an oxidized state and X. By the presence of nickel and/or cobalt in an oxidation state that is not complexed with X, the structural stability of the catalyst for carboxylate production will be further improved, and the increase in pore diameter and the resulting increase in the long-term reaction will be suppressed. Particle growth of composite particles. This effect becomes remarkable when an aluminum-containing silica-based composition containing silica and alumina is used as a carrier as described later.

Hereinafter, the effect of increasing the structural stability of the catalyst for carboxylate production by allowing nickel and/or cobalt in an oxidized state to exist alone on the carrier to suppress the increase in pore diameter caused by long-term reaction will be described. Larger and consequent particle growth of composite particles.

As described later, in the synthesis reaction of carboxylic acid ester, the compound of alkali metal or alkaline earth metal is added to the reaction system, and the pH value of the reaction system is maintained at 6-9, more preferably neutral conditions (for example, pH6.5-7.5 ), that is, as close to pH 7 as possible, thereby suppressing by-products such as acetals due to acidic substances represented by methacrylic acid or acrylic acid, which are inherent by-products of the production reaction of carboxylic acid esters.

According to the studies of the inventors of the present invention, the above-mentioned reaction operation is carried out using a gold particle-carrying material in which a single-component gold particle is supported on a carrier containing an aluminum-containing silica-based composition containing silica and alumina. In the case of a long-time reaction, there is a tendency to gradually cause the structural change of the gold particle support. It is considered that this phenomenon is caused by the above-mentioned reaction operation, when the carrier particles are partially and repeatedly exposed to acid and alkali, part of the Al in the above-mentioned carrier is dissolved and precipitated, and the silica-alumina cross-linked structure is regenerated. Arrangement, so the pore diameter of the loaded particles expands. In addition, there is a tendency that the gold particles are sintered and the surface area decreases due to the change in pore diameter accompanying the change in pore diameter, so that the catalytic activity decreases.

On the other hand, by making the composite particles and nickel and/or cobalt in a separate oxidation state exist on the carrier, the structural stability of the carrier particles under the above-mentioned reaction operation can be improved, and the expansion of the pore diameter and the expansion of the composite particles can be suppressed. tendency to grow. It is considered that the main reason is that the nickel and/or cobalt in the above-mentioned oxidation state react with the constituent elements of the support to form nickel and/or cobalt-containing composite oxides such as oxide compounds or solid solutions of nickel and/or cobalt. The nickel compound acts on the stabilization of the silica-alumina cross-linked structure, and as a result, the structural change of the supported particle is greatly improved. The inventors of the present invention presume that the appearance of such a structure-stabilizing effect of the carrier is due to nickel and/or cobalt present in the oxidized state of the carrier. Therefore, it is considered that when the nickel and/or cobalt in the oxidized state contained in the composite particle is in contact with the carrier, the effect can be obtained naturally, and when the nickel and/or cobalt in the oxidized state exist alone on the carrier, A greater stabilization effect can be obtained.

The carrier of the catalyst for producing carboxylate esters in this embodiment is not particularly limited as long as it can support nickel and/or cobalt and X in an oxidized state, and the catalyst carrier used in the previous chemical synthesis can be used .

As the carrier, for example, activated carbon, silica, alumina, silica-alumina, titania, silica-titania, zirconia, magnesia, silica-magnesia, silica- Alumina-magnesia, calcium carbonate, zinc oxide, zeolite, crystalline metal silicate and other supports. Preferably activated carbon, silica, alumina, silica-alumina, silica-magnesia, silica-alumina-magnesia, titania, silica-titania, zirconia, more preferably For silica-alumina, silica-alumina-magnesia.

In addition, the carrier may also contain a single element selected from alkali metals (Li, Na, K, Rb, Cs), alkaline earth metals (Be, Mg, Ca, Sr, Ba), and rare earth metals (La, Ce, Pr). Or a plurality of metal components. As the metal component to be supported, for example, one which becomes an oxide by baking of nitrate, acetate, etc. is preferable.

As the carrier, a carrier comprising an aluminum-containing silica-based composition containing silica and aluminum is preferably used. That is, the carrier preferably contains silica and alumina. The above carrier has higher water resistance than silica, and higher acid resistance than alumina. In addition, it is harder than activated carbon, has higher mechanical strength, etc., and has excellent physical properties than conventionally used supports, and can stably support nickel and/or cobalt and X in an oxidation state as active components. As a result, the catalyst for carboxylic acid ester production can maintain high reactivity for a long time.

Nickel and/or cobalt in an oxidized state and X have a specific atomic ratio, and the catalyst for the production of carboxylate using an aluminum-containing silica-based composition as a carrier has a suitable performance when used as a catalyst for chemical synthesis. It has a relatively high surface area used as a catalyst carrier, and has high mechanical strength, physical stability, and satisfies the corrosion resistance to the inherent acidity and alkalinity of the reaction.

Hereinafter, the characteristics of the carrier comprising the oxidized aluminum-containing silica-based composition containing silica and alumina according to the present embodiment, which can significantly improve the life of the catalyst, will be described. The reason why the mechanical strength and chemical stability of the carrier can be greatly improved is presumed as follows.

It is believed that the carrier containing aluminum-containing silica-based composition newly forms Si-O-Al-O-Si bonds by adding aluminum (Al) to the uncrosslinked silica (Si-O) chain of silica gel, thereby The Al cross-linked structure is formed without losing the original stability of the Si-O chain against acidic substances, whereby the Si-O bond is strengthened, so that the hydrolysis resistance stability (hereinafter, also referred to as "water resistance") especially improve. In addition, it is considered that when a Si-O-Al-O-Si cross-linked structure is formed, Si-O uncross-linked chains are reduced compared with the case of silica gel alone, and the mechanical strength is also increased. That is, it is presumed that the amount of Si-O-Al-O-Si structure formed is related to the improvement of the mechanical strength and water resistance of the obtained silica gel.

One of the reasons why nickel and/or cobalt and X in an oxidized state can be stably supported on the carrier for a long time is that the above-mentioned carrier has greatly improved mechanical strength and chemical stability compared with conventionally used carriers. Has excellent physical properties. As a result, it is considered that nickel and/or cobalt, which are active components, are not easily separated from X and can be stably loaded for a long time.

It is believed that commonly used supports, such as silica or silica-titania, will slowly dissolve nickel and/or cobalt components during the long-term reaction. On the other hand, the inventors of the present invention found that when the above carrier is used, the elution of nickel and/or cobalt components can be suppressed for a long time. According to the results of X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM/EDX), and double crystal high-resolution fluorescent X-ray analysis (HRXRF), it was confirmed that when using silicon dioxide or silicon dioxide - In the case of a titania carrier, the eluted nickel and/or cobalt components are nickel oxide or cobalt oxide present alone on the carrier. Since nickel oxide or cobalt oxide is a compound soluble in acid, when it is used as a catalyst for carboxylate synthesis, it is presumed that it is caused by the acidic substance represented by methacrylic acid or acrylic acid, which is an inherent by-product of this reaction. Dissolution.

The nickel and/or cobalt in the catalyst for carboxylic acid ester production according to the present embodiment is estimated from the analysis of the chemical state of nickel and/or cobalt by twin crystal high-resolution fluorescent X-ray analysis (HRXRF). Not only nickel oxide and/or cobalt oxide as a single compound, but an oxide compound or solid solution of nickel and/or cobalt formed by bonding nickel oxide and/or cobalt oxide to the constituent elements of the support, Or these mixtures etc. contain the composite oxide of nickel and/or cobalt.

The energy resolution of twin-crystal high-resolution fluorescent X-ray analysis (HRXRF) is extremely high, and the chemical state can be analyzed according to the energy position (chemical shift) and shape of the obtained spectrum. Especially in the Kα spectrum of 3d transition metal elements, with the change of valence number and electronic state, the chemical shift and shape will change, and the chemical state can be analyzed in detail. In the catalyst for producing carboxylate according to the present embodiment, the NiKα spectrum changes, and it was confirmed that the chemical state of nickel is different from that of nickel oxide which is a single compound.

For example, nickel aluminate formed from nickel oxide and aluminum oxide is an acid-insoluble compound. It is presumed that the formation of this nickel compound on the support will greatly improve the dissolution of nickel components.

With regard to the preferred elemental composition of the carrier comprising an aluminum-containing silica-based composition containing silica and alumina, the amount of aluminum is 1 to 30 mol% relative to the total molar amount of silicon and aluminum, which is relatively It is preferably in the range of 5-30 mol%, more preferably in the range of 5-25 mol%. There exists a tendency for acid resistance and mechanical strength to become favorable that the quantity of aluminum exists in the said range.

Also, from the viewpoint of further improving the mechanical strength and chemical stability, the carrier in the catalyst for the production of carboxylate according to the present embodiment preferably contains, in addition to silicon dioxide and alumina, a carrier selected from alkali metals, alkaline earth Oxides of at least one basic metal among metals and rare earth metals. The alkali metal of the basic metal component includes Li, Na, K, Rb, and Cs, the alkaline earth metal includes Be, Mg, Ca, Sr, Ba, etc., and the rare earth metal includes La, Ce, etc. , Pr. Among the above, Mg which is an alkaline earth metal is preferable, and it is particularly preferable that the carrier contains silica, alumina, and magnesia.

Concerning the elemental composition of a carrier containing silica, alumina, and an oxide of at least one alkali metal among alkali metals, alkaline earth metals, and rare earth metals, the amount of aluminum is 1 relative to the total molar amount of silicon and aluminum ~30 mol%, preferably 5-30 mol%, more preferably 5-25 mol%. Also, the composition ratio of the basic metal oxide to alumina is preferably 0.5 to 10, more preferably 0.5 to 5.0 in terms of (alkali metal + 1/2 x alkaline earth metal + 1/3 x rare earth metal)/Al atomic ratio, Furthermore, it is more preferably in the range of 0.5 to 2.0. If the elemental composition of silicon dioxide, alumina and basic metal oxides is within the above range, there is a tendency that silicon, aluminum and basic metal oxides form a specific stable bond structure, and as a result, the mechanical strength of the carrier And water resistance becomes good.

Next, a preferred method for preparing the carrier will be described by taking the case of using an aluminum-containing silica-based composition containing silica and alumina as an example, but the method for preparing the carrier is not limited to the following. That is, a carrier is prepared by preparing an aluminum-containing silica-based composition by reacting a silica sol with an aluminum compound solution.

In the above examples, silica sol was used as the silica source. In this case, mix silica sol and aluminum compound to obtain a mixture sol containing silica sol and aluminum compound, perform a multi-stage hydrothermal reaction at 20-100°C for 1-48 hours, and then dry to obtain a gel , roasting under the temperature, time, and environmental conditions described later; or add an alkaline aqueous solution to the above-mentioned mixture sol to co-precipitate silicon dioxide and aluminum compounds, dry them, and then roast under the conditions described later. In addition, by using a spray dryer to pulverize the above-mentioned mixture sol, or drying the above-mentioned mixture sol and granulating the gel, it is also possible to produce aluminum-containing silica with a desired particle size. It is the carrier of the composition.

Regarding the preparation method of the carrier containing silicon dioxide, aluminum oxide, and an oxide of at least one alkali metal among alkali metals, alkaline earth metals, and rare earth metals, it can be carried out according to the above-mentioned aluminum-containing dioxide containing silicon dioxide and aluminum oxide. The preparation method of the carrier of the silicon-based composition is carried out by drying the slurry obtained by mixing the alkali metal compound, alkaline earth metal compound and/or rare earth metal compound in the silicon dioxide and aluminum components, and then proceeding under the conditions described later Prepared by roasting.

As raw materials for alkali metals, alkaline earth metals, and rare earth metals, generally commercially available compounds can be used in the same manner as aluminum raw materials. Preferred are water-soluble compounds, more preferred are hydroxides, carbonates, nitrates, and acetates.

As another production method, a method of adsorbing an alkaline metal component selected from alkali metals, alkaline earth metals, and rare earth metals on a carrier containing an aluminum-containing silica-based composition can be used. For example, the following methods can be applied: a method using an impregnation method in which a carrier is added to a liquid in which a basic metal compound is dissolved, and drying treatment is performed; The method of impregnation. However, in the method of adsorbing the basic metal component afterward, it is necessary to pay attention to performing liquid drying treatment under mild conditions after highly dispersing the basic metal component on the carrier.

In addition, in order to control the properties of the slurry, fine-tune the characteristics of the product such as the pore structure and the physical properties of the obtained carrier, inorganic and organic substances can be added to the mixed slurry of the above-mentioned various raw materials.

Specific examples of inorganic substances to be used include: inorganic acids such as nitric acid, hydrochloric acid, and sulfuric acid; metal salts of alkali metals such as Li, Na, K, Rb, and Cs; alkaline earth metals such as Mg, Ca, Sr, and Ba; and Water-soluble compounds such as ammonia and ammonium nitrate; and clay minerals that disperse in water to produce a suspension. Moreover, specific examples of organic substances include polymers such as polyethylene glycol, methylcellulose, polyvinyl alcohol, polyacrylic acid, and polyacrylamide.

The effects of adding inorganic and organic substances are various. The main effect lies in the formation of spherical carriers, the control of pore diameter and pore volume, etc. Specifically, in order to obtain spherical carriers, the important factor is the liquid quality of the mixed slurry. By using inorganic or organic substances to adjust the viscosity and solid content concentration, it can be changed to a liquid quality that is easy to obtain a spherical carrier. Moreover, the control of pore diameter and pore volume can be implemented by the multistage hydrothermal synthesis process of the mixed slurry mentioned later. In addition, it is also preferable to use an appropriate selection of an optimal organic compound that remains inside the carrier during the molding stage and can be removed by firing and washing operations after molding.

(Manufacturing method of catalyst for carboxylic acid ester production) The method for producing the catalyst for producing carboxylate is not particularly limited, but the catalyst for producing carboxylate having a bulk density within a predetermined range and a predetermined particle size distribution according to the present embodiment can be easily obtained by the following method.

The preferred production method of the catalyst for the production of carboxylic acid esters of the present embodiment includes: Step I, which is to spray-dry the mixed slurry in a dryer using a rotating disc method; Step II, which is to spray-dry the resulting The material is calcined to obtain a carrier; and step III, which is to load the catalytic metal particles on the carrier. Furthermore, in the method for producing a catalyst for carboxylic acid ester production according to the present embodiment, in the above-mentioned step I, the feeding amount of the mixed slurry to be sprayed relative to the lateral radius of the spray dryer is 5×10 ^-3 m ² /Hr is more than 70×10 ^-3 m ² /Hr, and the peripheral speed of the disk is not less than 10 m/s and not more than 120 m/s. According to the above-mentioned method, the bulk density and particle size distribution of the predetermined range of the catalyst for production of carboxylate according to the present embodiment can be easily obtained, thereby obtaining a catalyst for production of carboxylate which suppresses the outflow of the catalyst and exhibits high activity.

When preparing the mixed slurry used in the step I of this embodiment, for example, the stirring operation of the raw material mixed liquid can be performed while properly adjusting the heating conditions.

The carrier in this embodiment can be produced by spray-drying the mixed slurry containing the above-mentioned various raw materials and additives as in steps I to II. As a method of making the mixed slurry droplet, known spraying devices such as a rotating disk system, a two-fluid nozzle system, and a pressurized nozzle system can be used.

The liquid to be sprayed (mixed slurry) is preferably used in a well-mixed state (a state in which the components are sufficiently dispersed). In the case of a good mixed state, there is a tendency to reduce the adverse effects on the performance of the carrier, such as the decrease in durability caused by the segregated presence of each component. Especially when preparing the raw material mixture, the viscosity of the slurry may increase and local gelation (condensation of colloids) may occur, and there is concern about the formation of uneven particles. Therefore, sometimes it is better to carry out the following operations: In addition to slowly mixing the raw materials under stirring, etc., it is also possible to control the metastable region of the silica sol near pH 2 by adding an acid or alkali, etc. modulation.

The liquid to be sprayed (mixed slurry) preferably has a certain degree of viscosity and solid content concentration. When the viscosity and solid content concentration are above a certain level, it can prevent the porous body obtained by spray drying from becoming a sunken sphere rather than a true sphere. Also, when the viscosity and the solid content concentration are below a certain level, in addition to ensuring the dispersibility of the porous bodies, it tends to contribute to the formation of stable droplets. Furthermore, the change in viscosity (final ⊿ viscosity) from 1 hour before the start of spray drying (the state of the raw material mixture) to spraying (the state of the mixed slurry) for 1 hour has an effect on the particle size distribution and bulk density obtained by spray drying. Tendency to make an impact. In view of the above, the final ⊿ viscosity is preferably not more than 10 mPa·s/Hr, more preferably not more than 7 mPa·s/Hr, further preferably not more than 5 mPa·s/Hr. The lower limit of the final ⊿ viscosity is not particularly limited, for example, it is 0 mPa・s/Hr or more. The final ⊿ viscosity can be measured based on the method described in the examples described later. Also, from the viewpoint of shape, bulk density, and particle diameter, the solid content concentration is preferably in the range of 10 to 50% by mass. Furthermore, the speed of the tip of the stirring blade when stirring the raw material mixture is not particularly limited, but from the viewpoint of controlling the final ⊿ viscosity, it is preferably from 3 m/s to 9 m/s, more preferably from 4 m/s to 8 m/s or less, more preferably 5 m/s or more and 7 m/s or less.

In the case of spray-drying the mixed slurry by means of a rotating disk in a drier, the following conditions are preferable. The rotary disk type dryer is provided with disks, such as an atomizer, for example. The disc can be used to spray the mixed slurry and adjust the bulk density and particle size distribution of the dried product. Specifically, the feeding amount of the liquid to be sprayed relative to the lateral radius of the spray dryer is preferably 5×10 ^-3 m ² /Hr or more and 70×10 ^-3 m ² /Hr or less, more preferably 10×10 ^-3 m ² /Hr to 50×10 ^-3 m ² /Hr, more preferably 20×10 ^-3 m ² /Hr to 40×10 ^-3 m ² /Hr. Also, the peripheral speed of the disc is preferably from 10 m/s to 120 m/s, more preferably from 20 m/s to 100 m/s, and still more preferably from 30 m/s to 90 m/s.

The calcination temperature of the carrier is usually selected from the range of 200-800°C. If the firing is performed at a temperature exceeding 800° C., the specific surface area tends to decrease significantly, which is not preferable. Also, the firing environment is not particularly limited, but firing is usually performed in air or nitrogen. Also, the firing time can be determined according to the specific surface area after firing, and is usually 1 to 48 hours. Calcination conditions will change the physical properties of the carrier such as porosity, so it is necessary to select appropriate temperature conditions and heating conditions. If the firing temperature is too low, it tends to be difficult to maintain durability as a composite oxide, and if it is too high, there is a possibility that the pore volume may decrease. Moreover, it is preferable to raise temperature gradually by temperature programming etc. as a temperature raising condition. In the case of roasting at a rapidly high temperature, the gasification and combustion of inorganic and organic substances will become violent, and exposure to a high temperature above the set temperature will cause pulverization, so it is not good. Furthermore, the particle size distribution can also be controlled by adding a classification step after calcination or after catalyst loading. As a classifier, free scroll classifiers, such as a sieve or a vibrating screen, an inertial classifier, a forced vortex centrifugal classifier, a cyclone, etc. are mentioned.

In terms of the ease of loading of composite particles, the reactivity when used as a catalyst, the difficulty of desorption, and the reactivity, the specific surface area of the carrier is higher than that of BET (Brunauer-Emmett-Teller, Buert) nitrogen. In the measurement by the adsorption method, it is preferably at least 10 m ² /g, more preferably at least 20 m ² /g, and still more preferably at least 50 m ² /g. Also, there is no particular limitation from the viewpoint of activity, but from the viewpoint of mechanical strength and water resistance, it is preferably at most 700 m ² /g, more preferably at most 350 m ² /g, and still more preferably at most 300 m 2 /g. ² /g or less.

If the pore diameter of the support is less than 3 nm, the peeling properties of the supported metal tend to become better, but when used as a catalyst in a liquid phase reaction, etc., the diffusion resistance in the pores should not be too large so as not to affect the reaction. From the viewpoint of rate-limiting the diffusion process of the raw material and maintaining high reactivity, the pore diameter is preferably 3 nm or more. On the other hand, it is preferably 50 nm or less from the viewpoint of the difficulty of breaking the supported material and the difficulty of peeling off the supported metal. Therefore, the pore diameter of the carrier is preferably 3 nm to 50 nm, more preferably 3 nm to 30 nm. The pore volume is necessary for the presence of pores that support the composite nanoparticles. However, when the pore volume increases, the strength tends to decrease rapidly. Therefore, from the viewpoint of strength and loading properties, the pore volume is preferably in the range of 0.1 to 1.0 mL/g, more preferably in the range of 0.1 to 0.5 mL/g. The carrier of this embodiment preferably has a pore diameter and a pore volume that both satisfy the above-mentioned ranges.

The shape of the carrier is based on the reaction form. In the fixed bed, the hollow cylindrical and honeycomb shape with less pressure loss is selected. In the liquid phase slurry suspension condition, the spherical shape is usually selected and the most suitable choice is based on the reactivity and separation method. The form used for optimum particle size. For example, when a simple catalyst separation process using precipitation separation is usually used, the particle size is preferably 10-200 μm, more preferably 20-150 μm, and even more preferably Particle size of 30-150 μm. In the cross filter method, small particles of 0.1-20 μm or less are preferable because of their higher reactivity. According to the purpose of use, it can be used as a catalyst for chemical synthesis by changing its type and form.

The loading amount of nickel or cobalt in the oxidized state on the support is not particularly limited, and relative to the mass of the support, it is usually 0.01-20% by mass, preferably 0.1-10% by mass, more preferably 0.2-5% by mass, based on the mass of the support. % by mass, and more preferably 0.5 to 2% by mass. The amount of X supported on the carrier is usually 0.01 to 10% by mass, preferably 0.1 to 5% by mass, more preferably 0.2 to 2% by mass, and still more preferably 0.3 to 1.5% by mass, in terms of metal, relative to the mass of the carrier. , preferably 0.5 to 1.0% by mass.

Furthermore, in the present embodiment, the atomic ratio of nickel and/or cobalt to the constituent elements of the carrier described above exists in a preferable range. In the case of using the carrier of the aluminum-containing silica-based composition containing silica and alumina in this embodiment, the composition ratio of nickel or cobalt to alumina in the catalyst is determined by Ni/Al atomic ratio or The Co/Al atomic ratio is preferably from 0.01 to 1.0, more preferably from 0.02 to 0.8, and still more preferably from 0.04 to 0.6. Also, in the case of using a carrier containing silica, alumina, and an oxide of at least one alkali metal among alkali metals, alkaline earth metals, and rare earth metals, the composition of nickel or cobalt in the carrier and alumina The ratio is preferably 0.01 to 1.0 in terms of Ni/Al atomic ratio or Co/Al atomic ratio, more preferably 0.02 to 0.8, and still more preferably 0.04 to 0.6, and the composition ratio of nickel or cobalt to the basic metal component is Ni/(alkali metal+alkaline earth metal+rare earth metal) atomic ratio or Co/(alkali metal+alkaline earth metal+rare earth metal) atomic ratio is preferably 0.01 to 1.2, more preferably 0.02 to 1.0, still more preferably 0.04 ~0.6.

If the atomic ratio of nickel and/or cobalt to aluminum and basic metal oxides as carrier constituent elements is within the above range, the effect of improving the elution of nickel and/or cobalt and the structural change of the carrier particles becomes greater tendency. The reason for this is considered to be that nickel and/or cobalt, aluminum, and basic metal oxides form specific composite oxides within the above-mentioned range to form a stable bond structure.

In the catalyst for producing carboxylate according to this embodiment, in addition to nickel and/or cobalt and X in an oxidized state, a third component element may be contained as an active component. As the third component element, for example, titanium, vanadium, chromium, manganese, iron, zinc, gallium, zirconium, niobium, molybdenum, rhodium, cadmium, indium, tin, antimony, tellurium, hafnium, tantalum, tungsten, rhenium, Osmium, iridium, mercury, thallium, lead, bismuth, aluminum, boron, silicon, phosphorus. The content of these third component elements contained in the carrier is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass. Moreover, the catalyst for carboxylic acid ester production may contain at least 1 sort(s) of metal component selected from the group which consists of an alkali metal, an alkaline-earth metal, and a rare-earth metal. The content of alkali metals, alkaline earth metals and rare earth metals in the load is preferably selected from a range of 15% by mass or less.

In addition, these third component elements or alkali metals, alkaline earth metals, and rare earth metals may be contained in the carrier during the production or reaction of the catalyst for carboxylate production, or may be contained in the carrier in advance.

From the viewpoint of reactivity and the difficulty of desorption of active components, the specific surface area of the catalyst for producing carboxylate according to the present embodiment is preferably 20 to 350 m ² /g as measured by the BET nitrogen adsorption method, and more preferably It is preferably in the range of 50 to 300 m ² /g, more preferably in the range of 100 to 250 m ² /g.

The pore diameter of the catalyst for carboxylate production is derived from the pore structure of the carrier. If it is less than 3 nm, the peeling properties of the loaded metal component tend to be good, but it is not suitable as a catalyst in liquid phase reactions, etc. In the case of use, the pore diameter is preferably 3 nm or more from the viewpoint of not making the diffusion resistance in the pores too large so as not to limit the rate of the diffusion process of the reaction raw material, thereby maintaining a high reactivity. On the other hand, it is preferably 50 nm or less from the viewpoint of the difficulty of breaking the supported material and the difficulty of peeling off the supported composite particles. Therefore, the pore diameter of the catalyst for producing carboxylate is preferably 3 nm to 50 nm, more preferably 3 nm to 30 nm, and still more preferably 3 nm to 10 nm. From the viewpoint of loading characteristics and reaction characteristics, the pore volume is preferably in the range of 0.1 to 1.0 mL/g, more preferably in the range of 0.1 to 0.5 mL/g, and still more preferably in the range of 0.1 to 0.3 mL/g. In the catalyst for producing carboxylate according to the present embodiment, it is preferable that both the pore diameter and the pore volume satisfy the above-mentioned ranges.

[Manufacturing Method of Catalyst for Carboxylic Ester Production] It does not specifically limit as the manufacturing method of the catalyst for carboxylic acid ester manufacture of this embodiment, The following preferable process can be included. Each step will be described below.

As a first step, an aqueous slurry containing an oxide of at least one alkali metal selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals, and an aqueous slurry containing nickel and/or cobalt and X (X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper) and acidic aqueous solutions of soluble metal salts are mixed. The temperature is adjusted so that the temperature of the mixture of the two liquids becomes 60° C. or higher. In the mixture, a precursor of a catalyst for carboxylate production in which nickel and/or cobalt and X component are deposited on a carrier is produced.

Next, as the second step, if necessary, the precursor obtained in the first step is washed with water, dried, and then heat-treated to obtain a catalyst for carboxylic acid ester production.

According to this method, a catalyst for carboxylate production that has a support layer in which composite particles exist locally and does not contain composite particles in a region including the carrier center can be obtained.

In this embodiment, before the first step, it is preferable to carry out aging of the carrier loaded with an oxide of at least one alkali metal selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals in water. step. By pre-curing the carrier, a more distinct distribution layer of composite particles can be obtained. Regarding the effect of the maturation of the carrier, based on the results of the pore distribution measurement using the nitrogen adsorption method, it is presumed that it is caused by the rearrangement of the pore structure of the carrier, resulting in a more uniform and distinct pore structure. The curing temperature of the carrier can also be room temperature, but the change of the pore structure is relatively slow, so it is preferable to select from a temperature higher than room temperature, that is, within the range of 60-150°C. When performing under normal pressure, it is preferable to be in the range of 60-100 degreeC. Also, the aging treatment time varies depending on temperature conditions. For example, in the case of 90° C., it is preferably 1 minute to 5 hours, more preferably 1 to 60 minutes, and still more preferably 1 to 30 minutes. As the operation of the first step, the carrier can also be dried and calcined before use after aging of the carrier, but it is preferable to use a slurry obtained by dispersing the carrier in water, and a compound containing nickel and/or cobalt and X The acidic aqueous solution of the soluble metal salt is contacted to immobilize the nickel and/or cobalt and component X on the carrier insolubilized.

Nickel nitrate, nickel acetate, nickel chloride, etc. are mentioned as a nickel-containing soluble metal salt used for the preparation of a catalyst. Also, as the soluble metal salt containing X, for example, palladium chloride, palladium acetate, etc. can be exemplified when palladium is selected as X, ruthenium chloride, ruthenium nitrate, etc. can be exemplified when ruthenium is selected, and ruthenium nitrate can be exemplified when gold is selected In the case of silver, examples include chloroauric acid, sodium gold chloride, potassium dicyanate, diethylamine gold trichloride, gold cyanide, etc. In the case of silver, examples include silver chloride, silver nitrate, and the like.

The various concentrations of the aqueous solution containing nickel and/or cobalt and X are usually in the range of 0.0001-1.0 mol/L, preferably 0.001-0.5 mol/L, more preferably 0.005-0.2 mol/L. The ratio of nickel or cobalt and X in the aqueous solution is preferably in the range of 0.1 to 10, more preferably 0.2 to 5.0, and still more preferably 0.5 to 3.0 in terms of Ni/X atomic ratio or Co/X atomic ratio.

The temperature when the carrier is in contact with the acidic aqueous solution containing nickel and/or cobalt and the soluble metal salt of X is one of the important factors to control the distribution of composite particles. The amount of oxides of at least one basic metal in the group of rare earth metals varies, but if the temperature is too low, the reaction tends to slow down and the distribution of composite particles tends to expand. In the production method of this embodiment, from the viewpoint of obtaining a supporting layer in which more distinct composite particles exist locally, the temperature at the time of contacting the acidic aqueous solution containing nickel and/or cobalt and a soluble metal salt of X is If a higher reaction rate can be obtained, the temperature is preferably 60°C or higher, more preferably 70°C or higher, further preferably 80°C or higher, and especially preferably 90°C or higher. It is only necessary to mix the acidic aqueous solution and the water slurry so that the temperature of the liquid obtained by mixing it becomes 60°C or higher. Therefore, the aqueous slurry can be heated in advance to such an extent that the mixed liquid exceeds 60°C even if the acidic aqueous solution is added. Conversely, it is also possible to preheat only the acidic aqueous solution-. Of course, both the acidic aqueous solution and the water slurry can be heated to above 60° C. in advance.

The reaction can also be carried out under pressure at a temperature higher than the boiling point of the solution, but usually it is preferably carried out at a temperature lower than the boiling point in terms of ease of handling. The time for immobilizing the nickel and/or cobalt and the X component is not particularly limited, and varies depending on the carrier type, nickel and/or cobalt and X loading, ratio, and other conditions, but it is usually 1 minute to 5 minutes. hours, preferably within the range of 5 minutes to 3 hours, more preferably within the range of 5 minutes to 1 hour.

The production method of the catalyst for the production of carboxylic acid ester of the present embodiment is based on the following principle: by oxidation of at least one basic metal selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals preloaded on the carrier Chemical reaction with soluble metal salts containing nickel and/or cobalt and X, so that nickel and/or cobalt and X components are insoluble and immobilized. In order to make the composite of nickel and/or cobalt and X component more sufficient, it is preferable to immobilize simultaneously from the mixed aqueous solution of both components.

In addition, in the production method of the present embodiment, the aqueous slurry containing a carrier carrying an oxide of at least one alkali metal selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals preferably contains An alkaline metal salt of at least one of the group consisting of alkali metals, alkaline earth metals and rare earth metals.

Thereby, the metal blackening of X can be suppressed, the composite of nickel and/or cobalt and X can be promoted, and the distribution of composite particles can be controlled more precisely. It is speculated that the reason for this effect is that by adding at least one metal salt selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals to the aqueous solution, the amount of alkali metal preloaded on the carrier is controlled. Rate of chemical reaction of oxides, with soluble metal salts containing nickel and/or cobalt and X.

As the alkali metal salt of at least one selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals, water-soluble salts such as organic acid salts, nitrates, and chlorides of these metals can be used. One or more of them.

The amount of the alkali metal salt of at least one selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals varies depending on the amount and ratio of nickel and/or cobalt to the X component. The amount of basic metal oxide on the support is determined. Usually, it is 0.001 to 2 moles, preferably 0.005 to 1 moles, relative to the amount of nickel and/or cobalt and the X component in the aqueous solution.

In addition, it is preferable that the aqueous slurry containing the carrier carrying the oxide of at least one alkali metal selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals contains a soluble aluminum salt. As the soluble aluminum salt, aluminum chloride and aluminum nitrate can be used.

By adding a soluble aluminum salt to the aqueous slurry, an outer layer substantially free of composite particles can be formed on the outside of the supporting layer where the composite particles locally exist. It is also based on the above-mentioned principle of insoluble immobilization. As the soluble aluminum salt, soluble salts such as aluminum chloride and aluminum nitrate are used, and the aluminum is reacted on the outer surface of the carrier by chemical reaction with the basic metal oxide pre-loaded on the carrier to consume nickel and/or cobalt The reaction site with X, and the above-mentioned basic metal oxide, nickel and/or cobalt, and X component inside are fixed by reaction.

The amount of the aluminum component varies depending on how many μm the thickness of the layer not carrying the nickel and/or cobalt and the X component is to be set, and is also determined by the amount of the basic metal oxide supported on the carrier in advance. Usually, it is 0.001 to 2 times mole, preferably 0.005 to 1 times mole, relative to the amount of the basic metal oxide supported on the carrier.

The details of the mechanism by which the distribution of nickel and/or cobalt and X components are achieved are still unclear in many places. The diffusion speed in the body and the insolubilization speed of the component by chemical reaction are well balanced, so that the composite particles can be fixed in an extremely narrow area near the surface of the carrier.

In addition, in the case of forming an outer layer substantially free of composite particles on the outer surface of the carrier, it is estimated that when the aluminum reacts with the alkaline metal component near the outer surface of the carrier, the available and Nickel and/or cobalt and the alkaline metal components that react with the X component, and then when the nickel and/or cobalt and X are loaded, the reactive alkaline metal components near the outer surface of the carrier have been consumed, so the nickel and/or cobalt and X /or cobalt and X are immobilized by reacting with the basic metal oxide inside the carrier.

Next, the second step will be described. Before the heat treatment in the second step, the first precursor is washed with water and dried if necessary. The heating temperature of the first precursor is usually 40-900°C, preferably 80-800°C, more preferably 200-700°C, and still more preferably 300-600°C.

The heat treatment is in the following environment, that is, in the air (or in the atmosphere), in an oxidizing environment (oxygen, ozone, nitrogen oxides, carbon dioxide, hydrogen peroxide, hypochlorous acid, inorganic/organic peroxides, etc.) or inert Carried out in a gas environment (helium, argon, nitrogen, etc.). The heating time may be appropriately selected according to the heating temperature and the amount of the first precursor. In addition, the heat treatment can be performed under normal pressure, increased pressure or reduced pressure.

After the above-mentioned second step, reduction treatment may also be performed in a reducing environment (hydrogen, hydrazine, formalin, formic acid, etc.) if necessary. In this case, the oxidation state of nickel and/or cobalt will not be completely reduced to the treatment method of metal state. The temperature and time of the reduction treatment may be appropriately selected according to the type of the reducing agent, the type of X, and the amount of the catalyst.

Furthermore, after the above-mentioned heat treatment or reduction treatment, it can also be treated in the air (or in the atmosphere) or in an oxidative environment (oxygen, ozone, nitrogen oxides, carbon dioxide, hydrogen peroxide, hypochlorous acid, inorganic/organic peroxide) as required. oxides, etc.) for oxidation treatment. In this case, the temperature and time are appropriately selected according to the type of oxidizing agent, the type of X, and the amount of catalyst.

The third component elements other than nickel and/or cobalt and X can be added during preparation of the support or under reaction conditions. Alkali metals, alkaline earth metals and rare earth metals can also be added or added to the reaction system during catalyst preparation. In addition, the raw materials of the third component element, alkali metal, alkaline earth metal and rare earth metal are selected from organic acid salts, inorganic acid salts, hydroxides, and the like.

[Manufacturing method of carboxylate] The catalyst for carboxylic acid ester production of this embodiment can be used widely as a catalyst for chemical synthesis. For example, it can be used in the carboxylate formation reaction between aldehydes and alcohols, and the carboxylate formation reaction from alcohols. That is, the production method of the carboxylate of the present embodiment may include the steps of (a) reacting the aldehyde and the alcohol in the presence of the catalyst for producing the carboxylate of the present embodiment and oxygen, or (b) using One or more alcohols are reacted.

The catalyst for carboxylic acid ester production of this embodiment exhibits the outstanding effect especially when used as a catalyst of an oxidation reaction. As the reaction raw materials used in this embodiment, in addition to the aldehydes and alcohols used in the formation reaction of the carboxylate shown in the examples, various reaction raw materials such as alkanes, alkenes, Alcohols, ketones, aldehydes, ethers, aromatic compounds, phenols, sulfur compounds, phosphorus compounds, oxygen nitrogen compounds, amines, carbon monoxide, water, etc. These reaction raw material substances can be used individually or as a mixture containing 2 or more types. Oxidation products such as various industrially useful oxygenates, oxidation adducts, and oxidative dehydrogenation products are obtained from these reaction raw materials.

Regarding the reaction raw material, specifically, as alkanes, for example, methane, ethane, propane, n-butane, isobutane, n-pentane, n-hexane, 2-methylpentane, 3-methylpentane, Aliphatic alkanes such as pentane; cyclopentane, cyclohexane, cycloheptane, cyclooctane and other aliphatic alkanes.

Examples of olefins include ethylene, propylene, butene, pentene, hexene, heptene, octene, decene, 3-methyl-1-butene, 2,3-dimethyl-1 - Aliphatic olefins such as butene and allyl chloride; alicyclic olefins such as cyclopentene, cyclohexene, cycloheptene, cyclooctene, and cyclodecene; Group-substituted alkenes, etc.

Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, second butanol, third butanol, n-pentanol, n-hexanol, n-heptanol, allyl alcohol, croton Alcohol and other saturated and unsaturated aliphatic alcohols; cyclopentanol, cyclohexanol, cycloheptanol, methylcyclohexanol, cyclohexen-1-ol and other saturated and unsaturated alicyclic alcohols; ethylene glycol, propylene glycol , 1,3-propanediol, 1,3-butanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol and other aliphatic and alicyclic polyols; benzyl alcohol, salicyl alcohol, di Aromatic alcohols such as benzyl alcohol, etc.

Examples of aldehydes include: aliphatic saturated aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, and glyoxal; aliphatic α,β-unsaturated aldehydes such as acrolein, methacrolein, and crotonaldehyde. ; Aromatic aldehydes such as benzaldehyde, tolualdehyde, benzilaldehyde, phthalaldehyde, and derivatives of these aldehydes.

As ketones, for example, aliphatic ketones such as acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, methyl propyl ketone; cyclopentanone, cyclohexanone, cyclooctanone, 2 - Cycloaliphatic ketones such as methylcyclohexanone and 2-ethylcyclohexanone; aromatic ketones such as acetophenone, propiophenone, and benzophenone, etc.

As the aromatic compound, for example, benzene, toluene, xylene, naphthalene, anthracene, or derivatives thereof substituted with an alkyl group, an aryl group, a halogen group, a prylyl group, or the like may, for example, be mentioned.

The phenols include, for example, phenol, cresol, xylenol, naphthol, anthracene (anthol) (hydroxyanthracene) and their derivatives (the hydrogen atom of the aromatic ring is replaced by an alkyl group, an aryl group, a halogen atom , sulfonic acid group and other substitutes).

Examples of the sulfur compound include mercaptans such as methylmercaptan, ethanethiol, propanethiol, benzylmercaptan, and thiophenol.

As the amines, for example, methylamine, ethylamine, propylamine, isopropylamine, butylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, trimethylamine, triethylamine, trimethylamine, Aliphatic amines such as propylamine, tributylamine, allylamine and diallylamine; alicyclic amines such as cyclopentylamine, cyclohexylamine, cycloheptylamine and cyclooctylamine; aromatic amines such as aniline, benzylamine and toluidine, etc. .

These reaction raw material substances can be used individually or as a mixture containing 2 or more types. In addition, it does not necessarily have to be purified, and may be a mixture with other organic compounds.

Hereinafter, a method of producing a carboxylate from an aldehyde and an alcohol by an oxidative esterification reaction in the presence of oxygen using the catalyst for producing carboxylate according to the present embodiment will be described as an example.

As the aldehyde used as a raw material, for example: C ₁ -C ₁₀ aliphatic saturated aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, glyoxal; acrolein, methacrolein, crotonaldehyde, etc. ₃ ~ C ₁₀ aliphatic α, β-unsaturated aldehydes; C ₆ ~ C ₂₀ aromatic aldehydes such as benzaldehyde, methyl benzaldehyde, benzyl aldehyde, phthalaldehyde, etc.; and derivatives of these aldehydes. These aldehydes may be used alone or as a mixture of two or more of them. In this embodiment, the aldehyde is preferably selected from acrolein, methacrolein or a mixture thereof.

Examples of the alcohol include C ₁ -C ₁₀ aliphatic saturated alcohols such as methanol, ethanol, isopropanol, butanol, 2-ethylhexanol, and octanol; C ₅ -C 10 saturated alcohols such as cyclopentanol and cyclohexanol; C ₁₀ alicyclic alcohols; C ₂ -C ₁₀ diols such as ethylene glycol, propylene glycol, butylene glycol; C ₃ -C ₁₀ aliphatic unsaturated alcohols such as allyl alcohol and methallyl alcohol; benzyl alcohol, etc. ₆ ～C ₂₀ aromatic alcohols; 3-alkyl-3-hydroxymethyl oxetanes and other hydroxy oxetanes. These alcohols may be used alone or as a mixture of two or more of them. In this embodiment, preferably, the aldehyde is acrolein and/or methacrolein, and the alcohol is methanol.

The molar ratio of aldehyde to alcohol is not particularly limited. For example, it can be carried out in a wide range of 10 to 1/1,000 in terms of molar ratio of aldehyde/alcohol, but usually it is 1/2 in terms of molar ratio. ~1/50 within the scope of implementation.

The amount of catalyst used can be greatly changed according to the type of reaction raw material, composition and preparation method of catalyst, reaction conditions, reaction form, etc., and there is no special limit. When the catalyst is reacted in a slurry state, the The solid content concentration in the slurry is preferably 1 to 50% by mass/volume, more preferably 3 to 30% by mass/volume, and still more preferably 10 to 25% by mass/volume.

In the production of carboxylic acid ester, any method such as a gas phase reaction, a liquid phase reaction, or a trickle reaction can be used, and it can be implemented by any method of a batch type or a continuous type.

The reaction can also be carried out without a solvent, and a solvent inert to the reaction components can be used, such as hexane, decane, benzene, dioxane, and the like.

As the reaction form, previously known forms such as fixed bed type, fluidized bed type, and stirred tank type can also be used. For example, when implementing in a liquid phase, arbitrary reactor forms, such as a bubble column reactor, a draft tube reactor, and a stirred tank reactor, can be utilized.

The oxygen used in the production of carboxylate can be molecular oxygen, that is, oxygen itself or the form of a mixed gas obtained by diluting oxygen with a diluent that is inert to the reaction, such as nitrogen, carbon dioxide gas, etc., as an oxygen raw material, in terms of operability Air is preferably used from the viewpoint of economic efficiency and the like.

Oxygen partial pressure changes according to reaction materials such as aldehydes and alcohols, reaction conditions, or reactor form, etc. In practice, the oxygen partial pressure at the outlet of the reactor becomes a concentration range below the lower limit of the explosive range. For example, it is better to manage It is 20-80kPa. The reaction pressure can be carried out in any wide pressure range from reduced pressure to increased pressure, and it is usually carried out at a pressure in the range of 0.05 to 2 MPa. Also, from the viewpoint of safety, it is preferable to set the total pressure so that the oxygen concentration of the reactor effluent gas does not exceed the explosion limit (for example, the oxygen concentration is 8%).

In the case of carrying out the production reaction of carboxylate in a liquid phase, it is preferable to add an alkali metal or alkaline earth metal compound (for example, oxide, hydroxide, carbonate, carboxylate) to the reaction system and react The pH value of the system was maintained at 6-9. These alkali metal or alkaline earth metal compounds can be used alone or in combination of two or more.

The reaction temperature at the time of producing carboxylate can also be implemented at a high temperature of 200°C or higher, but is preferably 30-200°C, more preferably 40-150°C, and still more preferably 60-120°C. The reaction time is not particularly limited and varies depending on the set conditions, so it cannot be uniquely determined, but it is usually 1 to 20 hours. [Example]

Hereinafter, although an Example is given and this embodiment is demonstrated more concretely, this embodiment is not limited at all by these Examples.

In the following examples and comparative examples, various physical property measurements were implemented by the following methods.

[Determination of viscosity of mixed slurry] Viscosity was measured under the following conditions and at room temperature every hour since the stirring of the mixed slurry began. Viscometer: Brookfield Digital Viscometer "LVDV1M" Shaft: LV-1 Speed: 100 rpm Temperature: room temperature (25°C) The final ⊿ viscosity was defined as the difference between the viscosity in the spray dryer device just before the start of feeding and the viscosity 1 hour before the start of feeding.

[Determination of supported amounts of Ni and X and Ni/X atomic ratio] The concentrations of nickel and X in the composite particles were quantified using an IRIS Intrepid II XDL type ICP (Inductively Coupled Plasma, inductively coupled plasma) emission analyzer (ICP-AES, MS) manufactured by Thermo Fisher Scientific. The preparation of the sample is to weigh the load into a decomposition container made of Teflon, add nitric acid and hydrofluoric acid, use the ETHOS TC microwave decomposition device manufactured by Milestone General K.K for thermal decomposition, and then evaporate and dry on the heater , and then add nitric acid and hydrochloric acid to the precipitated residue, and use a microwave decomposition device to decompose under pressure, and use pure water to dilute the resulting decomposition solution to a volume as a test solution. Quantitative method is to use the internal standard method of ICP-AES to quantify, subtract the operation blank value implemented at the same time to obtain the content of nickel and X in the catalyst, and calculate the loading amount and atomic ratio.

[Analysis of the Crystal Structure of Composite Particles] Using the Rint2500 powder X-ray diffraction device (XRD) manufactured by Rigaku Company, in the X-ray source Cu bulb (40 kV, 200 mA), the measurement range is 5 to 65 deg (0.02 deg/step), and the measurement speed is 0.2 deg/ Min, the slit width (scattering, diverging, receiving light) under the conditions of 1 deg, 1 deg, 0.15 mm. The samples are evenly spread on the non-reflective sample plate and fixed with neoprene rubber.

[Analysis of the chemical state of the metal component of composite particles] Using the ESCALAB250 X-ray photoelectron spectroscopy (XPS) manufactured by Thermo Electron, the excitation source AlKα: 15 kV×10 mA, the analysis area: about 1 mm (shape: ellipse), the acquisition area: full-spectrum scanning 0-1,100 eV, under the condition of narrow scan Ni2p. The measurement sample is crushed with an agate mortar and the composite particle load, collected on a special sample stand for powder, and used for XPS measurement.

[Analysis of the chemical state of nickel] The XFRA190 dual crystal high-resolution fluorescent X-ray analyzer (HRXRF) manufactured by Technos was used to measure the NiKα spectrum, and the various parameters obtained were compared with those of the standard substances (nickel metal, nickel oxide). The chemical state such as the valence of nickel in the load. The measurement sample was used for measurement as it is. The determination of Kα spectrum of Ni is carried out in partial spectrum mode. At this time, Ge(220) was used as the spectroscopic crystal, and one with a longitudinal divergence angle of 1° was used as the slit, and the excitation voltage and current were set to 35 kV and 80 mA, respectively. In addition, the standard sample uses filter paper as an absorber, and the load sample is measured so that the counting time is selected for each sample so that the peak intensity of the Kα spectrum becomes 3,000 cps or less and 10,000 counts or more. The measurement was repeated 5 times for each sample, and the measurement of the metal sample was performed before and after the repeated measurement. After smoothing the measured spectrum (S-G method 7 points-5 times), calculate the peak position, full width at half maximum (FWHM), asymmetry coefficient (AI), and the peak position is taken as the metal measured before and after the sample measurement The offset and chemical shift (ΔE) of the measured value of the sample are processed.

[morphological observation and elemental analysis of composite particles] TEM bright-field images were measured using a 3100FEF transmission electron microscope/scanning transmission electron microscope (TEM/STEM) manufactured by JEOL Corporation [accelerating voltage 300 kV, with energy dispersive X-ray detector (EDX)] , STEM darkfield image, STEM-EDS composition analysis (point analysis, mapping, line analysis). Data analysis software system uses TEM image and STEM image analysis (length measurement, Fourier transform analysis): DigitalMicrographTM Ver.1.70.16, Gatan, EDS data analysis (mapping image processing, composition quantitative calculation): NORAN System SIX ver.2.0, Thermo Fisher Scientific. The measurement sample was crushed with a mortar, dispersed in ethanol, ultrasonically cleaned for about 1 minute, then dropped onto Mo grinding sand and air-dried to serve as a sample for TEM/STEM observation.

[Determination of UV-Vis Spectroscopy of Composite Particles] Using the V-550 UV-Vis spectrophotometer (UV-Vis) manufactured by JASCO Corporation [with an integrating sphere unit and a holder for powder samples], the measurement range is 800-200 nm, and the scanning speed is 400 nm/min. conduct. The measurement sample was pulverized with an agate mortar, and the composite particle carrier was placed in a powder sample holder and subjected to UV-Vis measurement.

[Shapes Observation of Carriers and Catalysts for Carboxylate Production] The carrier and the catalyst for carboxylate production were observed using a Hitachi X-650 scanning electron microscope (SEM).

[Measurement of D ₁₀ , D ₅₀ , D ₉₀ and FWHM W of catalysts for production of carboxylic acid esters] Take 0.2 g of catalysts in a beaker, add 16 mL of purified water, and use SONIC & MATERIALS.INC. A VCX130-type ultrasonic disperser was used to disperse for 1 minute to prepare a sample for measurement. For this measurement sample, the particle size at which the cumulative frequency becomes x% in the volume-based particle size distribution of the catalyst for carboxylic acid ester production was measured using a laser diffraction-scattering particle size distribution measuring device LS230 manufactured by Beckman Coulter Co. D _x (D ₁₀ , D ₅₀ and D ₉₀ ) and the full width at half maximum W of the particle size distribution (volume basis).

[specific surface area] The specific surface area was measured by the BET method using Quadrasorb from Quantachrome.

[Measurement of Bulk Density (CBD) of Catalysts for Carboxylate Production] As a pretreatment, about 120 g of the catalyst for carboxylate production was taken in a stainless steel crucible, and dried for 6 hours in a 150° C. muffle furnace. After roasting, add to a desiccator (with silica gel added) and cool to room temperature. Then, take 100.0 g of the pretreated catalyst for carboxylic acid ester production, transfer it to a 250 mL graduated cylinder, and fill the graduated cylinder with vibration for 15 minutes using a vibrator. Thereafter, the surface of the sample in the graduated cylinder is flattened, and the filling volume is read. The bulk density is a value obtained by dividing the mass of the catalyst for carboxylate production by the filled volume.

[Outflow rate] Based on the total amount of the catalyst used in the production of the carboxylate to be described later and the amount of catalyst remaining after 500 hours of production of the carboxylate, the outflow rate was calculated by the following formula. Outflow rate={1－(residual catalyst amount/catalyst amount used in the reaction)}×100[%] Here, the remaining catalyst amount is the mass of catalyst obtained by drying the catalyst for carboxylic acid ester production at 130° C. for 500 hours after the production of carboxylic acid ester was carried out for 10 hours. That is, the catalyst with a high outflow rate tends to flow out of the reactor, so it is difficult to remain in the reactor, and the catalyst for the reaction will be reduced under long-term operation, so the conversion rate tends to deteriorate as a result.

[Example 1] (Manufacture of catalyst for carboxylate production) An aqueous solution prepared by dissolving 3.75 kg of aluminum nitrate nonahydrate, 2.56 kg of magnesium nitrate, and 540 g of 60% by mass nitric acid in 5.0 L of pure water was slowly dropped Adjust the pH to 1.8 in 20.0 kg of a silica sol solution (SiO ₂ content: 30% by mass) with a colloidal particle size of 10-20 nm in a stirring state maintained at 15°C. The temperature of the raw material mixture (solid content: 25% by mass) containing silica sol, aluminum nitrate, and magnesium nitrate obtained in this way was raised to 55°C. Then, the raw material mixture was stirred for 30 hours at the tip speed of the stirring blade at 5.5 m/s to obtain a mixed slurry with a final Δ viscosity of 0.5 mPa·s/Hr. Thereafter, the slurry was fed by the spray dryer device so that the feed rate/SD radius became 25×10 ^-3 [m ² ], and the disk (atomizer) peripheral speed was 80 m/s. Spray dried to obtain a solid. Furthermore, the SD radius refers to the lateral radius of the spray dryer in the form of a rotating disk used in this example. Next, the obtained solid was filled with a thickness of about 1 cm in a stainless steel container with an open top, and the temperature was raised from room temperature to 300° C. in an electric furnace for 2 hours, and then held for 3 hours. Furthermore, it heated up to 600 degreeC over 2 hours, held it for 3 hours, and then cooled slowly, and obtained the carrier. The obtained carrier contained 83.3 mol%, 8.3 mol%, and 8.3 mol% of silicon, aluminum, and magnesium, respectively, relative to the total molar amount of silicon, aluminum, and magnesium. In addition, according to the observation with a scanning electron microscope (SEM), the shape of the carrier was approximately spherical.

300 g of the carrier obtained in the above manner was dispersed in 1.0 L of water heated at 90°C, and stirred at 90°C for 15 minutes. Then, an aqueous solution containing 16.35 g of nickel nitrate hexahydrate and 12 mL of chloroauric acid aqueous solution of 1.3 mol/L and heated to 90° C. was added to the above-mentioned carrier slurry, and stirred at 90° C. for 30 minutes, and The nickel and gold components are insoluble and immobilized on the carrier. Then, after standing still, the supernatant was removed, washed several times with distilled water, and then filtered. After drying it at 105°C for 10 hours with a dryer, it was baked in air at 450°C for 5 hours in a muffle furnace to obtain a carboxylic acid ester production catalyst loaded with 1.05% by mass of nickel and 0.91% by mass of gold. Media (NiOAu/SiO ₂ -Al ₂ O ₃ -MgO composite particle support). The Ni/Au atomic ratio of the obtained catalyst for carboxylic acid ester production was 4.0. A sample obtained by embedding and grinding the obtained composite particle carrier in a resin was subjected to line analysis of the particle cross section using an X-ray microprobe (EPMA). As a result, it was confirmed that there was an outer layer substantially free of nickel and gold in a depth region of 0.5 μm from the outermost surface of the carrier, nickel and gold were supported in a depth region from the surface to 10 μm, and inside the carrier There are no composite particles. Next, the shape of the above-mentioned composite particle-loaded material was observed by a transmission electron microscope (TEM/STEM). spherical nanoparticles. If the nanoparticle is further zoomed in and observed, lattice fringes corresponding to the interplanar spacing of Au(111) are observed in the nanoparticle. STEM-EDS composition point analysis was performed on each nanoparticle. As a result, nickel and gold were detected in any particle. The average value (calculated number: 50) of the nickel/gold atomic ratio of the nanoparticles was 1.05. Furthermore, the nanoscale analysis of the observed particles showed that the Ni/Au atomic ratio was 0.90 at the center of the particle and 2.56 at the edge of the particle. In parts other than particles, only a trace amount of nickel was detected. The same measurement was carried out at 50 points, and a large amount of nickel was detected around the edge of any particle. According to the EDS elemental mapping, it is observed that the distribution of nickel and gold is roughly consistent. Also, according to the spectral line profile of the composition, the distribution of nickel is larger than that of gold in any scanning direction. According to the results of powder X-ray diffraction (XRD), no diffraction pattern derived from nickel was observed, and it was confirmed that it existed in an amorphous state. On the other hand, although it cannot be said to be a clear peak, there is a broad peak equivalent to a gold crystal. Although it is a value close to the detection limit (2 nm) of powder X-ray diffraction, the average crystallite diameter is about 3 nm when calculated using Scherrer's formula. Regarding the chemical state of nickel, it was confirmed that nickel is divalent according to the results of X-ray photoelectron spectroscopy (XPS). According to the results of double crystal high-resolution fluorescent X-ray analysis (HRXRF), the chemical state of nickel is speculated to be high-spin 2 valence of nickel, and according to the difference of NiKα spectrum, it is clear that the chemical state is different from that of nickel oxide as a single compound . The full width at half maximum (FWHM) of the NiKα spectrum of the catalyst obtained from the measured spectrum is 3.470, and the chemical shift (ΔE) is 0.335. The full width at half maximum (FWHM) of the NiKα spectrum of nickel oxide measured as a standard substance was 3.249, and the chemical shift (ΔE) was 0.344. In addition, using ultraviolet-visible spectroscopy (UV-Vis) to study the change of the electron excitation state of the composite particle loading, the result did not appear near 530 nm from the surface plasmonic absorption peak of gold nanoparticles, but at 200 nm _A broad absorption originating from NiO2 was confirmed in the ~800 nm wavelength region. From the above results, it is presumed that the fine structure of the composite particles has a form in which the surface of the gold nanoparticles is covered with nickel in an oxidized state.

(Evaluation of Physical Properties of Catalyst for Carboxylate Production) The specific surface area of the obtained catalyst for production of carboxylate was determined to be 141 m ² /g. In addition, the particle size distribution was obtained from the results obtained by measuring the particle size distribution by the laser-scattering method for the catalyst for carboxylic acid ester production. As a result, the half maximum width W of the particle size distribution was 50 μm, D ₅₀ , D ₁₀ /D ₅₀ , The values of D ₉₀ /D ₅₀ and W/D ₅₀ are 60 μm, 0.7, 1.5 and 0.8, respectively. The particle size distribution is a single peak. Also, when the bulk density was measured, it was 1.05 g/cm ³ .

(Manufacture of Carboxylate) 240 g of the obtained catalyst for carboxylate production was added to a stirring type stainless steel reactor equipped with a catalyst separator and a liquid phase portion of 1.2 L, and the speed of the front end of the stirring blade was Stir the content at a speed of 4 m/s, while implementing the reaction of oxidized carboxylate from aldehyde and alcohol. That is, a 36.7% by mass methacrolein/methanol solution was continuously supplied to the reactor at 0.6 L/hr, and a 1 to 4% by mass NaOH/methanol solution was continuously supplied to the reactor at 0.06 L/hr. Air was blown in at a pressure of 0.5 mPa so that the outlet oxygen concentration was 8.0% by volume, and the NaOH concentration supplied to the reactor was controlled so that the pH of the reaction system became 7. The reaction product leaked continuously from the outlet of the reactor due to overflow, and was analyzed by gas chromatography to study reactivity. The conversion rate of methacrolein was 72% and the selectivity rate of methyl methacrylate was 95% within 500 hours from the start of the reaction. Also, the outflow rate of the catalyst was 2%.

[Examples 2 to 7 and Comparative Examples 1 to 7] A catalyst for carboxylate production was produced in the same manner as in Example 1, except that the preparation conditions and spray drying conditions of the mixed slurry at the time of carrier production were changed as shown in Table 1. That is, (i) by increasing or decreasing the amount of pure water that dissolves aluminum nitrate nonahydrate and magnesium nitrate in the raw material mixture, the amount of solid content is adjusted to the value in Table 1, (ii) by adjusting The amount of 60% by mass nitric acid was increased or decreased to adjust the pH value to the value in Table 1. The physical properties of the catalyst for the production of the carboxylate were evaluated in the same manner as in Example 1, and further, using it, the carboxylate was produced in the same way as in Example 1, and the reaction performance and the outflow rate of the catalyst were calculated. . Furthermore, the volume-based particle size distribution of the catalysts of Examples 2-7 is a single peak. These results are shown in Table 1.

[Table 1] Carrier Manufacturing Conditions Catalysts for Carboxylate Production Manufacture of Carboxylate Preparation conditions of mixed slurry Spray drying conditions FWHM: W (μm) Bulk density (g/cm ³ ) Average particle size: D ₅₀ (μm) D ₁₀ /D ₅₀ D ₉₀ /D ₅₀ W/D ₅₀ outflow rate conversion rate/selection rate Solid content mass% pH value temperature °C Time Hr Stirring blade front speed m/s Final ⊿ viscosity mPa・s/Hr Feed amount/SD radius×10 ^-3 Atomizer peripheral speed m/s Example 1 25 1.8 55 30 5.5 0.5 25 80 50 1.05 60 0.7 1.5 0.8 2% 72%/95% Example 2 30 2 60 30 5.5 0.5 25 80 48 1.07 62 0.6 1.4 0.8 3% 70%/92% Example 3 35 2.2 55 35 5.1 0.5 10 34 60 1.09 73 0.7 1.6 0.8 4% 68%/93% Example 4 25 1.8 50 40 6.4 2 25 80 50 0.67 60 0.7 1.5 0.8 7% 64%/91% Example 5 40 1.2 60 30 4.3 6 25 80 50 133 60 0.7 1.5 0.8 3% 67%/93% Example 6 20 2.0 50 40 7.1 4 25 100 65 0.90 52 0.3 1.6 1.3 6% 65%/91% Example 7 25 2.0 60 28 4.0 7 40 90 120 1.12 83 0.7 2.3 1.4 3% 69%/92% Comparative example 1 25 1.8 50 twenty four 3.7 10 20 150 70 0.82 45 0.1 1.8 1.6 12% 56%/85% Comparative example 2 25 1.8 50 twenty four 3.7 10 20 75 95 0.80 60 0.8 2.6 1.6 4% 61%/87% Comparative example 3 25 2 15 36 9.2 17 20 75 92 0.48 62 0.4 2.0 1.5 14% 54%/80% Comparative example 4 25 2 15 36 9.2 18 20 135 72 0.62 41 0.1 1.9 1.8 13% 55%/85% Comparative Example 5 25 2 15 36 9.2 17 5 75 57 0.64 45 0.1 1.5 1.3 12% 52%/82% Comparative Example 6 35 2 20 25 2.2 12 20 75 100 1.55 56 0.6 2.8 1.8 6% 56%/82% Comparative Example 7 25 0.5 55 20 5.5 20 20 140 83 0.62 48 0.1 1.9 1.7 11% 56%/85%

Claims (16)

A catalyst for producing carboxylate, which comprises catalyst metal particles and a carrier carrying the catalyst metal particles, wherein the bulk density of the catalyst for carboxylate production is 0.50 g/ ^cm3 or more and 1.50 g/cm3 ³ or less, D ₁₀ /D ₅₀ ≧0.2 and D ₉₀ /D ₅₀ ≦2.5 when D _x is the particle size whose cumulative frequency becomes x% in the volume-based particle size distribution of the above-mentioned carboxylic acid ester production catalyst , W/D ₅₀ ≦1.5 when the full width at half maximum of the above-mentioned particle size distribution is W. The catalyst for producing carboxylate according to claim 1, wherein the above-mentioned W is 100 μm or less. The catalyst for producing carboxylate according to claim 1 or 2, wherein the catalytic metal particles contain at least one element selected from the group consisting of nickel, cobalt, palladium, platinum, ruthenium, lead, gold, silver and copper . As the catalyst for the production of carboxylate according to any one of claims 1 to 3, wherein the above-mentioned catalytic metal particles are nickel and/or cobalt and X (X represents nickel, palladium, platinum, ruthenium, Composite particles of at least one element in the group consisting of gold, silver and copper). The catalyst for producing carboxylate according to claim 4, wherein the composition ratio of nickel or cobalt to X in the composite particles is 0.1-10 in terms of Ni/X atomic ratio or Co/X atomic ratio. The catalyst for producing carboxylate according to claim 4 or 5, wherein the composite particles contain nickel or cobalt in an oxidized state, and gold. The catalyst for producing carboxylate according to any one of claims 4 to 6, wherein the average particle diameter of the above-mentioned composite particles is 2 to 10 nm. The catalyst for producing carboxylate according to any one of claims 4 to 7, wherein the supporting layer where the composite particles are locally present exists from the surface of the catalyst for producing carboxylate to the carboxylate The area up to 40% of the equivalent diameter of the catalyst used for manufacturing. As the catalyst for the production of carboxylate according to any one of claims 4 to 8, wherein the above-mentioned equivalent diameter is 200 μm or less, and the supporting layer where the above-mentioned composite particles exist locally is present in the catalyst for the production of carboxylate from the above-mentioned The area from the surface of the catalyst to 30% of the equivalent diameter of the above-mentioned catalyst for producing carboxylate. The catalyst for producing carboxylate according to any one of Claims 4 to 9, wherein an outer layer substantially free of composite particles is provided on the outside of the supporting layer where the composite particles locally exist, and the outer layer is composed of Formed with a thickness of 0.01-15 μm. The catalyst for producing carboxylate according to any one of claims 4 to 10, wherein the composite particle has a core containing X, and the core is covered with nickel or cobalt in an oxidized state. The catalyst for producing carboxylate according to any one of claims 1 to 11, wherein the carrier contains silica and alumina. The catalyst for producing carboxylate according to any one of claims 1 to 12, wherein the above-mentioned D ₅₀ is not less than 10 μm and not more than 200 μm. A method for producing a carboxylate, comprising the steps of: (a) reacting an aldehyde with an alcohol, or ( b) Reacting one or more alcohols. The method for producing a carboxylic acid ester according to claim 14, wherein the above-mentioned aldehyde is acrolein and/or methacrolein. The method for producing a carboxylic acid ester according to claim 14 or 15, wherein the above-mentioned aldehyde is acrolein and/or methacrolein, and the above-mentioned alcohol is methanol.