TWI763398B - Catalyst for producing carboxylate, method for producing carboxylate, and method for producing catalyst for producing carboxylate - Google Patents

Abstract

A catalyst for the manufacture of carboxylate, comprising catalyst metal particles and a carrier for supporting the catalyst metal particles, wherein the bulk density of the catalyst for the manufacture of carboxylate is 0.50 g/cm ³ or more and 1.50 g/cm ³ or less, when D ₁₀ /D ₅₀ ≧ 0.2 and D ₉₀ /D ₅₀ ≦2.5, when the particle diameter whose frequency is accumulated to x% in the volume-based particle size distribution of the catalyst for the production of carboxylate is set as D _x , W/D ₅₀ ≦1.5 when the half-height width of the particle size distribution is set to W.

Description

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

The present invention relates to a catalyst for producing a carboxylate, a method for producing a carboxylate, and a method for producing a catalyst for producing a 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, various modifications and improvements of nickel-based catalysts have been used to achieve aerobic oxidation of alcohols under catalysts. . However, in the chemical industry, it is well known that nickel and nickel compounds are widely effective not only in the oxidation reaction of alcohol, but also in 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 a carboxylate, Patent Document 1 proposes to use a composite particle-supported material containing nickel in an oxidized state and X (X represents a group selected from nickel) as a catalyst , at least one element of the group consisting of palladium, platinum, ruthenium, gold, silver, and copper) composed of composite particles, and a carrier supporting the above composite particles, and having the support that the above composite particles exist locally. Floor. According to this catalyst, it is considered that high reactivity can be maintained for a long time.

Patent Document 2 describes silica spherical particles containing aluminum and magnesium and having a specific surface area, pore volume, pore distribution, bulk density, abrasion resistance, average particle size, aluminum content, and magnesium content. within the specified range. It is considered that according to this document, 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 Literature]

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

[Problems to be Solved by Invention]

For the production of carboxylate using the catalysts described in Patent Documents 1 and 2, it is required to increase the catalyst activity and to express a catalyst with a higher conversion rate. The inventors of the present invention repeatedly conducted experiments on the production of carboxylate, and found that the conversion of the raw material tends to gradually decrease when the catalysts described in Patent Documents 1 and 2 are used to produce carboxylate for a long period of time. The reason for this was investigated in more detail, and as a result, it was found that the outflow of the catalyst from the reactor and the fluidity of the catalyst had an influence on the conversion rate of the raw material. Furthermore, although the addition rate of raw materials and the selectivity of carboxylate can be improved by increasing the amount of air blowing in the production of carboxylate, when the catalyst tends to flow out of the reactor, the rate of addition of air increases. As the amount of blowing increases, the effect of catalyst outflow becomes more pronounced, and in this respect, it also becomes a hindrance to the improvement of the reaction performance.

The present invention has been accomplished in view of the above-mentioned problems of the prior art, and an object thereof is to provide a catalyst for carboxylate production that suppresses the outflow of the catalyst and exhibits high activity. [Technical means to solve problems]

The present inventors 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 ) in predetermined ranges, and completed the present invention.

That is, the present invention includes the following aspects. [1] A catalyst for producing carboxylate, comprising catalyst metal particles and a carrier supporting the catalyst metal particles, wherein the bulk density of the catalyst for producing carboxylate is 0.50 g/cm ³ or more and 1.50 g/cm ³ or less, when the particle size at which the frequency is accumulated to x% in the volume-based particle size distribution of the catalyst for the production of carboxylate is defined as _Dx , D ₁₀ /D ₅₀ ≧ 0.2 and D ₉₀ /D ₅₀ ≦2.5, W/D ₅₀ ≦1.5, when the half width of the particle size distribution is set to W. [2] The catalyst for carboxylate production according to [1], wherein the above W is 100 μm or less. [3] The catalyst for carboxylate production according to [1] or [2], wherein the catalyst metal particles contain a group 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 carboxylate production 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 group selected from nickel and palladium) , at least one element of the group consisting of platinum, ruthenium, gold, silver and copper) composite particles. [5] The catalyst for carboxylate production according to [4], wherein the composition ratio of nickel or cobalt to X in the composite particles is 0.1 to 10 in terms of Ni/X atomic ratio or Co/X atomic ratio. [6] The catalyst for carboxylate production according to [4] or [5], wherein the composite particles contain nickel or cobalt in an oxidized state, and gold. [7] The catalyst for carboxylate production according to any one of [4] to [6], wherein the average particle diameter of the composite particles is 2 to 10 nm. [8] The catalyst for carboxylate production according to any one of [4] to [7], wherein the support layer in which the composite particles are locally present is present on the surface of the catalyst for carboxylate production from the above The region up to 40% of the equivalent diameter of the catalyst for the production of the above-mentioned carboxylate. [9] The catalyst for carboxylate production according to any one of [4] to [8], wherein the equivalent diameter is 200 μm or less, and the support layer locally present in the composite particles is present in the catalyst from the above The area from the surface of the catalyst for carboxylate production to 30% of the equivalent diameter of the catalyst for carboxylate production. [10] The catalyst for carboxylate production according to any one of [4] to [9], wherein there is an outer layer substantially free of composite particles on the outside of the support layer where the composite particles are locally present , and the outer layer is formed with a thickness of 0.01-15 μm. [11] The catalyst for carboxylate production according to any one of [4] to [10], wherein the composite particle has a core containing X, and the core is coated with nickel or cobalt in an oxidized state. [12] The catalyst for carboxylate production according to any one of [1] to [11], wherein the carrier contains silica and alumina. [13] The catalyst for carboxylate production according to any one of [1] to [12], wherein the above D ₅₀ is 10 μm or more and 200 μm or less. [14] A method for producing a carboxylate, comprising the steps of: (a) making an aldehyde and an alcohol in the presence of a catalyst for producing a carboxylate and oxygen according to any one of [1] to [13] The reaction is carried out, or (b) one or two or more kinds of alcohols are allowed to react. [15] The method for producing a carboxylate according to [14], wherein the aldehyde is acrolein and/or methacrolein. [16] The method for producing a carboxylate according to [14] or [15], wherein the aldehyde is acrolein and/or methacrolein, and the alcohol is methanol. [Effect of invention]

ADVANTAGE OF THE INVENTION According to this invention, the catalyst for carboxylate production which suppresses the outflow of a catalyst and shows high activity can be provided.

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 carried out within the range of the summary.

[Catalyst for carboxylate production] The catalyst for carboxylate production according to the present embodiment includes catalytic metal particles and a carrier for supporting the above-mentioned catalytic metal particles, and the bulk density of the above-mentioned catalyst for carboxylate production is 0.5 g/cm ³ to 1.5 g/cm ³ When the cumulative frequency of the particle size distribution becomes x%, the particle size is set as D _x , D ₁₀ /D ₅₀ ≧ 0.2 and D ₉₀ /D ₅₀ ≦2.5, and the half-height width of the volume-based particle size distribution is set as W , W/D ₅₀ ≦1.5. Since it is comprised in this way, the catalyst for carboxylate production of this embodiment suppresses the outflow of a catalyst, and shows high activity.

In this embodiment, the bulk density of the catalyst for carboxylate production is 0.50 g/cm ³ or more and 1.50 g/cm ³ or less. Although it is considered that the above-mentioned bulk density has a small relationship with the subject related to the decrease in catalyst activity, it is considered that by adjusting the bulk density to the above-mentioned 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 value, the catalyst will flow out of the reactor under long-term operation, the amount of the catalyst will decrease, and thus the activity will become low, and if the bulk density is greater than the above-mentioned upper limit value, the catalyst will flow out. The circulation is low, so the contact with the raw material is impaired, and the activity becomes low. From such a viewpoint, the bulk density of the catalyst for carboxylate production is preferably 0.70 g/cm ³ or more and 1.30 g/cm ³ or less, more preferably 0.90 g/cm ³ or more and 1.20 g/cm ³ or less. The said bulk density can be measured by the method described in the Example mentioned later. The above-mentioned bulk density can be adjusted to the above-mentioned range by, for example, adopting preferable production conditions and the like to be described later.

D ₁₀ /D ₅₀ is 0.2 or more, when the particle size at which the frequency is accumulated to _x % in the volume-based particle size distribution of the catalyst for carboxylate production is defined as Dx. D ₁₀ /D ₅₀ is an index indicating to what extent particles with small particle diameters exist relative to the average particle diameter as a catalyst for carboxylate production, and 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|liquidity of the catalyst for carboxylate production improves, and it shows high activity. From the same viewpoint, D ₁₀ /D ₅₀ is preferably 0.3 to 0.8. D ₁₀ /D ₅₀ can be measured by the laser diffraction-scattering method, and more specifically, can be measured by the method described in the examples described later. For example, D ₁₀ /D ₅₀ can be adjusted to the above-mentioned range by adopting preferable manufacturing conditions and the like described later.

In this embodiment, D ₉₀ /D ₅₀ is 2.5 or more. This is an index indicating to what extent particles with large particle diameters exist relative to the average particle diameter as a catalyst for carboxylate 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 _D90 / _D50 2.5 or more, the fluidity|liquidity of the catalyst for carboxylate production improves, and it expresses high activity. 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, can be measured by the method described in the examples described later. For example, D ₉₀ /D ₅₀ can be adjusted to the above-mentioned range by adopting preferable production conditions and the like described later.

W/D ₅₀ is 1.5 or less when the half width of the particle size distribution based on the volume of the catalyst for carboxylate production is set to W. W/D ₅₀ is an index indicating to what extent the half width of the peak in the above-mentioned particle size distribution is widened relative to the average particle size, and a smaller value indicates a steeper distribution. In this embodiment, by setting W/D ₅₀ to be 1.5 or less, the fluidity of the catalyst for carboxylate production is improved while suppressing the outflow of the catalyst, thereby suppressing the outflow of the catalyst and exhibiting high activity. In addition, when there are a plurality of peaks in the above particle size distribution, W with respect to the highest peak is made to satisfy the above relationship. From the same viewpoint, W/D ₅₀ is preferably 0.6 to 1.3. W/D ₅₀ can be measured by a laser diffraction-scattering method, and more specifically, can be measured by the method described in the examples described later. For example, W/D ₅₀ can be adjusted to the above-mentioned range by adopting preferable manufacturing conditions and the like described later.

In this embodiment, the above-mentioned W is preferably 100 μm or less. By making the value of W 100 μm or less, there is a tendency that the outflow of the catalyst can be further suppressed. It is considered that not only the above-mentioned bulk density, but also the above-mentioned half-height width is less related to the problem related to the reduction of catalyst activity. However, by adjusting the half-height width to the above-mentioned range, there is a tendency to prevent the catalyst from flowing out of the reactor. , and subsequently, the conversion rate of raw materials increases. Furthermore, it was not previously known that depending on the particle size distribution of the catalyst, there is an outflow of the catalyst from the reactor to such an extent that the conversion rate of the raw material is affected, which is a novel insight. From the same viewpoint, W is more preferably 5 μm or more and 95 μm or less, and still more preferably 10 μm or more and 90 μm or less. W can be measured by a laser diffraction-scattering method, and more specifically, it can be measured by the method described in the examples described later. For example, W can be adjusted to the above-mentioned range by adopting preferable manufacturing conditions and the like to be described later.

D ₅₀ in this embodiment is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less, more preferably 40 μm or more and 100 μm or less, and still more preferably 40 μm or more and 80 μm or less. 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 a higher activity. _D50 can be measured by the laser diffraction-scattering method, and more specifically, it can be measured by the method described in the Example mentioned later. For example, _D50 can be adjusted to the above-mentioned range by adopting preferable manufacturing conditions and the like which will be described later.

In this embodiment, the particle size distribution of the catalyst is preferably a single peak. The so-called particle size distribution is a single peak means that in the particle size distribution based on volume, except for the highest peak, there are no peaks more than 1/5 of the highest peak.

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

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

The catalyst for carboxylate production of the present embodiment can have various sizes and various shapes in the order of μm to cm in substantial thickness or particle size. Specific examples of the shape of the catalyst for carboxylate production are not limited to the following, but include spherical, elliptical, cylindrical, tablet-like, hollow cylindrical, plate-like, rod-like, sheet-like, Honeycomb and other shapes. The shape can be appropriately changed according to the reaction form, but is not limited to the following. For example, in the fixed-bed reaction, the shape of hollow cylinder and honeycomb with less pressure loss is selected. shape.

The term "equivalent diameter" as used herein means the diameter of a spherical particle, or in the case of an irregularly shaped particle, the diameter of a sphere of the same volume as the particle or a sphere with the same surface area as the particle. The measuring method of the equivalent diameter is to measure D50 _by using a particle size distribution measuring device of laser diffraction-scattering method, and the measured _D50 is taken as the equivalent diameter.

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

On the other hand, when the equivalent diameter of the catalyst for carboxylate production is 200 μm or less, it is preferable to support the composite particles from the surface of the catalyst for carboxylate production to the catalyst for carboxylate production in the area up to 30% of the equivalent diameter of the medium. Especially in the case of liquid-phase reaction, the reaction rate and the diffusion rate of reaction substances in the pores of the carrier will be affected. Therefore, previously, the design of reducing the particle size of the carrier by coordinating the reaction was adopted. In the present embodiment, by reducing the thickness of the support layer locally present in the composite particles, a catalyst for the production of carboxylate with higher activity can be obtained without reducing the particle size of the support. In this case, there is also an advantage that the catalyst can be easily separated by precipitation, and a small-capacity separator can be used for separation. On the other hand, if the volume of the part in which the composite particles are not supported in the catalyst for producing carboxylate becomes too large, the volume that is not required for the reaction in each reactor may become large and wasteful. 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 where the desired composite particles are locally present, and the thickness of the layer where the composite particles are not supported.

The catalyst for carboxylate production may have an outer layer that does not substantially contain composite particles on the outside of the support layer in which the composite particles are locally present. The outer layer is preferably formed with a thickness of 0.01-15 μm from the outer surface of the carrier. By setting the outer layer in this range, it can be used as anti-contact in the reaction of the reactor that is concerned with the friction of catalyst particles, such as the fluidized layer, the bubble column, the stirred reactor, or the reaction that causes the accumulation of toxic substances. It is used as a catalyst that suppresses the shedding of composite particles due to abrasion. In addition, since the outer layer can be controlled to be extremely thin, a significant decrease in activity can be suppressed.

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

In this embodiment, the term "substantially free of composite particles" means that the relative intensity is substantially absent in the secondary electron reflection image of the X-ray microprobe analysis method or high-resolution scanning electron microscope described later. Peaks in the distribution of nickel and/or cobalt in an oxidation state of more than 10% and X (X represents at least one element selected from the group consisting of nickel, palladium, platinum, ruthenium, gold, silver and copper).

The nickel which can constitute the oxidized state of the composite particles in the present embodiment is preferably a nickel oxide (for example, Ni ₂ O, NiO, NiO ₂ , Ni ₃ O ₄ , Ni ₂ O ) formed by bonding between nickel and oxygen. ₃ ); or nickel, X and/or one or more other metal elements, and nickel oxide compounds or solid solutions formed by bonding with oxygen, or nickel-containing composite oxides such as mixtures of these. Further, as the cobalt which can constitute the oxidized state of the composite particles in the present embodiment, cobalt oxide (for example, CoO, Co ₂ O ₃ , Co ₃ O ₄ ) formed by bonding between cobalt and oxygen is preferable; or cobalt , X and/or one or more other metal elements, and cobalt oxide compounds or solid solutions formed by bonding with oxygen, or cobalt-containing composite oxides such as mixtures of these.

The term "nickel oxide" as used herein refers to a compound containing nickel and oxygen. Nickel oxides include Ni ₂ O, NiO, NiO ₂ , Ni ₃ O ₄ , Ni ₂ O ₃ or hydrates of these exemplified above, nickel hydroperoxides containing OOH groups or nickel containing O ₂ groups peroxides, or mixtures of these.

In addition, the term "composite oxide" referred to here means an oxide containing two or more kinds of metals. "Composite oxide" is an oxide formed by two or more metal oxides forming a compound, including polyoxides in which ions of oxoacids do not exist as structural units (for example, nickel perovskite oxides, spinel oxides Stone-type oxides), but it is a broader concept than polyoxides, including all oxides composed of two or more kinds of metals. Oxides in which two or more metal oxides form a solid solution are also in the category of complex oxides.

Regarding the catalyst for carboxylate production of the present embodiment, when the nickel oxide and/or cobalt oxide and X are complexed as described above, there is a tendency that the nickel oxide having oxidative esterification activity and the /or the original catalytic ability of cobalt oxides is brought out, showing remarkably high catalyst performance that cannot be achieved with catalysts comprising each single component. It is considered that it is a special effect manifested by the complexation of nickel oxide and/or cobalt oxide with X, the bifunctional effect between the two metal components or the generation of new active species, etc., and each single component is produced. A completely different new catalyst 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 that epoch-making catalyst performance that cannot be obtained by conventional catalysts can be realized in particular.

For example, when gold is selected as X, and nickel oxide and gold are highly dispersed and supported on the carrier, there is a tendency to exhibit remarkably high catalytic performance. Compared with catalysts in which nickel oxide or gold is supported on a carrier as a single component, such a catalyst for carboxylate production has a higher selectivity of carboxylate, and a significant increase in the selectivity of carboxylate 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-supported material containing each single component, and the development of the catalytic function resulting from the complexation is strongly dependent on the support of nickel and gold. composition. The reason for this is presumed to be that there is an optimum ratio for the formation of an oxidation state of nickel that is most suitable for the reaction. By supporting the two components of nickel oxide and gold in a dispersed manner on the carrier as described above, there is a tendency to exhibit a remarkable composite effect that cannot be expected based on the simple addition of the individual components.

The catalyst for carboxylate production in which gold is selected as X as described above allows nickel and gold in oxidized state to be highly dispersed and supported on the carrier, and the two components tend to be complexed in nanometer size. When such a catalyst for carboxylate production is observed with a transmission electron microscope/scanning transmission electron microscope (TEM/STEM), generally spherical nanoparticles of 2 to 3 nm are observed uniformly. A structure that is dispersed and supported on a carrier. In addition, when it is used for elemental analysis of nanoparticles by 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 on the carrier by a single component. Furthermore, the presence of metal can be confirmed by applying X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (powder XRD), and typically gold is observed as a crystalline metal. On the other hand, Nickel exists as an amorphous oxide having a valence of 2. Furthermore, if it is used for ultraviolet-visible spectroscopy (UV-Vis), which can observe the change of the excited state of electrons, it is typical to observe the gold nanoparticles derived from gold nanoparticles observed for the gold nanoparticles of 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 the surface plasmon absorption peak is caused by other metal oxide species other than nickel oxide (such as chromium oxide, manganese oxide, iron oxide, cobalt oxide, copper oxide, and zinc oxide, etc.) that have no effect on the reaction. oxide) in combination with gold was not observed in the catalyst. It is considered that the disappearance of the surface plasmon absorption peak is caused by the mixing of electronic states at the contact interface of nickel and gold in the oxidized state, that is, caused by the recombination of the two metal chemical species. Furthermore, the conversion to the highly oxidized nickel oxide can be confirmed by the hue change of the catalyst and ultraviolet-visible spectroscopy (UV-Vis). By adding gold to nickel oxide, nickel oxide changes from gray-green to dark-brown, and absorbs across the visible region and roughly overall in the UV spectrum. The shape of the UV spectrum and the color of the catalyst were similar to those of the highly oxidized nickel peroxide (NiO ₂ ) measured as a reference sample. As described above, it is presumed that nickel oxide is converted into nickel oxide in a highly oxidized state by the addition of gold. From the above results, it is considered that the structure of the composite particles when gold is selected as X is a form in which the gold particles are the cores, the surfaces of which are covered with highly oxidized nickel oxides, and there are no gold atoms on the surfaces of the composite particles.

The composite particles are preferably supported on a carrier in a highly dispersed state. The composite particles are preferably dispersed and supported in the form of microparticles or films, and the average particle size thereof 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-mentioned range, a specific active species structure including nickel and/or cobalt and X tends to be formed, thereby increasing 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 contrast portion is a composite particle, and the diameter of each particle can be measured and the number average thereof 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 0.2 to 8.0, still more preferably 0.3 to 6.0 in terms of Ni/X atomic ratio or Co/X atomic ratio . When the atomic ratio of Ni/X or the atomic ratio of Co/X is within the above range, there is a tendency to form a specific active species structure including nickel and/or cobalt and X, and an oxidation state of nickel and/or cobalt that is most suitable for the reaction , as a result, the activity and selectivity are 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 has a phase structure such as a random chemical species The solid solution structure that occupies the lattice site of the crystal, the core-shell structure that the various chemical species are separated in concentric spheres, the anisotropic phase-separated structure that separates the anisotropic phases, and the two chemical species exist adjacent to the particle surface Arbitrary structure of heterobondphilic structure. 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 spherical or hemispherical may be used.

As an analytical method for observing the morphology of the composite particles, for example, as described above, a transmission electron microscope/scanning transmission electron microscope (TEM/STEM) is effective by irradiating a nanoparticle image observed by TEM/STEM. The electron beam can be used to analyze the elements in the particles and describe the distribution of the elements. It was confirmed that the composite particles in the present embodiment contained nickel and/or cobalt and X in any particle, and the surface of X was coated with nickel and/or cobalt, as shown in the examples described later. In the case of such a form, the atomic ratio of nickel and/or cobalt to X varies depending on the position of the composition analysis point in the particle, and more nickel and / or cobalt. Therefore, in each particle, depending on the position of the analysis point, the atomic ratio of nickel or cobalt to X has a range which is included in the above-mentioned range of Ni/X atomic ratio or Co/X atomic ratio.

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

The solid form of nickel is not particularly limited as long as it can obtain a predetermined activity, but it is preferably an amorphous form in which no diffraction peak is observed by X-ray diffraction. By adopting this form, it is presumed that when used as a catalyst for an oxidation reaction, the interaction with oxygen increases, and furthermore, since the junction interface between nickel and X in an oxidized state increases, it is possible to obtain a 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 any one of metal, oxide, hydroxide, complex compound containing X and nickel, cobalt or one or more other metal elements, or a mixture of these, and the preferred chemical state is metal or oxide material, more preferably metal. In addition, the solid form of X is not particularly limited as long as a predetermined activity can be obtained, and any form of crystalline or amorphous may be used.

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

The catalyst for carboxylate production of the present embodiment functions by supporting nickel and/or cobalt and X in an oxidized state on a carrier as described above to form composite particles containing nickel and/or cobalt and X in an oxidized state Excellent effect. In addition, the term "composite particle" in this embodiment refers to a particle containing different binary metal species in one particle. Examples of binary metal species different from this include binary metal particles in which two components of nickel and/or cobalt and X are metals, metal particles that form alloys or intermetallic compounds of nickel and/or cobalt and X, and the like. When this is the case as a catalyst for chemical synthesis, the selectivity of the target product and the catalyst activity tend to be lower than those of the catalyst for carboxylate production of the present embodiment.

The catalyst for carboxylate production of the present 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 oxidized state that is not complexed with X, the structural stability of the catalyst for carboxylate production is further improved, and the increase in the pore diameter caused by the long-term reaction and the consequent increase in the pore diameter are 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 and suppressing the increase in pore diameter due to long-term reaction by allowing nickel and/or cobalt in an oxidized state to exist solely on the carrier will be explained. Large and consequent particle growth of composite particles.

As will be described later, in the synthesis reaction of the carboxylate, an alkali metal or alkaline earth metal compound is added to the reaction system, and the pH of the reaction system is maintained at 6 to 9, more preferably under neutral conditions (for example, pH 6.5 to 7.5 ), that is, in the vicinity of pH 7 as much as possible, by-production of acetal and the like based on acidic substances represented by methacrylic acid or acrylic acid, which are inherent by-products of the carboxylate production reaction, can be suppressed.

According to the study of the present inventors, the above-mentioned reaction operation was carried out using a gold particle-supported material in which a single-component gold particle was supported on a carrier comprising an aluminum-containing silica-based composition containing silica and alumina. In the case of a long-term reaction, there is a tendency to gradually change the structure of the gold particle-supported material. This phenomenon is believed to be caused by the fact that, through the above-mentioned reaction operation, the supported particles are locally and repeatedly exposed to acid and alkali, and part of Al in the above-mentioned support is partially dissolved and precipitated, resulting in the formation of a silica-alumina cross-linked structure again. Arrangement, so the pore diameter of the supported particles expands. In addition, there is a tendency that the sintering of gold particles occurs with the change in the expansion of the pore diameter, so that the surface area decreases, and the catalyst activity decreases.

On the other hand, by allowing the composite particles and individual oxidized nickel and/or cobalt to exist on the carrier, the structural stability of the carrier particles under the above-mentioned reaction operation is improved, the expansion of the pore diameter and the reduction of the composite particles are suppressed. Tendency to grow. The main reason for this is considered to be that the nickel and/or cobalt in the oxidized state as described above reacts with the constituent elements of the carrier to form an oxide compound of nickel and/or cobalt or a composite oxide containing nickel and/or cobalt such as a solid solution. The nickel compound acts on the stabilization of the silica-alumina cross-linked structure, and as a result, the structural change of the supported particles is greatly improved. The inventors of the present invention presume that the structure-stabilizing effect of such a carrier occurs due to nickel and/or cobalt existing in an oxidized state of the carrier. Therefore, it is considered that when nickel and/or cobalt in an oxidized state contained in the composite particles is in contact with the carrier, this effect can be obtained, and when nickel and/or cobalt in an oxidized state exist alone on the carrier, Greater stabilization effect can be obtained.

The carrier of the catalyst for carboxylate production of the present 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-magnesium oxide, calcium carbonate, zinc oxide, zeolite, crystalline metal silicate and other carriers. 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 the group consisting of alkali metals (Li, Na, K, Rb, Cs), alkaline earth metals (Be, Mg, Ca, Sr, Ba), and rare earth metals (La, Ce, Pr) or multiple metal components. As a metal component to be supported, it is preferable that it becomes an oxide by, for example, calcination of nitrate, acetate, or the like.

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-mentioned carrier has higher water resistance than silica and higher acid resistance than alumina. In addition, it is harder than activated carbon and has higher mechanical strength, and has excellent physical properties compared to conventionally used carriers, and can stably support nickel and/or cobalt and X in an oxidized state as active components. As a result, the catalyst for carboxylate production can maintain high reactivity for a long time.

Nickel and/or cobalt in the oxidized state has a specific atomic ratio to X, and the catalyst for the manufacture of carboxylate with an aluminum-containing silica-based composition as a carrier is suitable when used as a catalyst for chemical synthesis. It has a high surface area used as a catalyst carrier, and has high mechanical strength, stable physical properties, and meets the corrosion resistance to the inherent acid and alkali of the reaction.

Hereinafter, the characteristics of the carrier including the oxidic alumina-containing silica-based composition containing silica and alumina according to this embodiment, which can greatly improve the catalyst life, 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 the aluminum-containing silica-based composition newly forms Si-O-Al-O-Si bonds by adding aluminum (Al) to the uncrosslinked silica (Si-O) chains of the silica gel, thereby The Al cross-linked structure is formed without losing the original stability of the Si-O chain to acidic substances, whereby the Si-O bond is strengthened, so that the hydrolysis resistance stability (hereinafter, also referred to as "water resistance") is particularly improve. In addition, it is considered that when the Si-O-Al-O-Si cross-linked structure is formed, the Si-O uncross-linked chain decreases compared with the case of the silica gel alone, thereby increasing the mechanical strength. That is, it is estimated that the formation amount of the Si-O-Al-O-Si structure correlates with the improvement of the mechanical strength and water resistance of the obtained silicone rubber.

One of the reasons why the oxidized nickel and/or cobalt and X can be stably supported on the carrier for a long period of time is that the above-mentioned carrier greatly improves the mechanical strength and chemical stability as described above, compared with the previously commonly used carrier. Has excellent physical properties. As a result, it is considered that nickel and/or cobalt, which are active components, and X are hardly peeled off and can be stably supported 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 long-term reactions. On the other hand, the inventors of the present invention found that the elution of nickel and/or cobalt components can be suppressed for a long time when the above-mentioned carrier is used. According to the results of X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM/EDX), and double crystal high-resolution X-ray fluorescence analysis (HRXRF), it was confirmed that the use of silica or silica - In the case of a titanium dioxide carrier, the eluted nickel and/or cobalt components are nickel oxide or cobalt oxide that are present on the carrier alone. Since nickel oxide or cobalt oxide is an acid-soluble compound, when it is used as a catalyst for carboxylate synthesis, it is presumed that it is caused by an acidic substance represented by methacrylic acid or acrylic acid, which is a by-product inherent in this reaction. Dissolution.

Based on the analysis of the chemical states of nickel and/or cobalt by twin-crystal high-resolution X-ray fluorescence analysis (HRXRF), it is estimated that nickel and/or cobalt in the catalyst for carboxylate production of the present embodiment 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 with constituent elements of the carrier, Or a mixture of these or the like contains a composite oxide of nickel and/or cobalt.

Double crystal type high-resolution X-ray fluorescence analysis (HRXRF) has extremely high energy resolution, and can analyze the chemical state according to the energy position (chemical shift) and shape of the obtained spectrum. Especially in the Kα spectrum of 3d transition metal elements, the chemical shift and shape will change with the change of valence and electronic state, and the chemical state can be analyzed in detail. Regarding the catalyst for carboxylate production of the present embodiment, the NiKα spectrum changed, and it was confirmed that the chemical state of nickel was 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 such a nickel compound on the carrier greatly improves the elution of the nickel component.

Regarding the preferred elemental composition of the carrier comprising the aluminum-containing silica-based composition containing silicon dioxide and aluminum oxide, the amount of aluminum is 1 to 30 mol % relative to the total molar amount of silicon and aluminum, compared with Preferably it is 5-30 mol%, More preferably, it is the range of 5-25 mol%. When the amount of aluminum is within the above range, acid resistance and mechanical strength tend to be good.

In addition, from the viewpoint of further improving mechanical strength and chemical stability, the carrier in the catalyst for carboxylate production according to the present embodiment preferably contains a material selected from the group consisting of alkali metals and alkaline earths in addition to silica and alumina. Oxides of at least one alkali metal among metals and rare earth metals. Li, Na, K, Rb, and Cs are mentioned as the alkali metal component of the basic metal component, Be, Mg, Ca, Sr, Ba, etc. are mentioned as the alkaline earth metal, and La and Ce are mentioned as the rare earth metal. , Pr. Among the above, Mg, which is an alkaline earth metal, is preferred, and the carrier preferably contains silica, alumina, and magnesia.

Regarding the elemental composition of the support 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 with respect to the total molar amount of silicon and aluminum ~30 mol %, preferably 5-30 mol %, more preferably 5-25 mol %. In addition, the composition ratio of the basic metal oxide and the alumina is (alkali metal+1/2×alkaline earth metal+1/3×rare earth metal)/Al atomic ratio, preferably 0.5 to 10, more preferably 0.5 to 5.0, More preferably, it is the range of 0.5-2.0. If the elemental composition of silicon dioxide, aluminum oxide and basic metal oxide is within the above range, there is a tendency that silicon, aluminum and basic metal oxide form a specific stable bonding structure, as a result, the mechanical strength of the carrier is and water resistance become good.

Next, a preferred method for preparing the carrier will be described by taking the case of using the 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 reacting a silica sol with an aluminum compound solution to prepare an aluminum-containing silica-based composition.

In the above example, silica sol was used as the source of silica. In this case, the silica sol and the aluminum compound are mixed to obtain a mixed sol containing the silica sol and the aluminum compound, which is subjected to a multi-stage hydrothermal reaction at 20-100° C. for 1-48 hours, and then dried to obtain a gel. , calcining under the following temperature, time, and environmental conditions; or adding an alkaline aqueous solution to the above-mentioned mixture sol to co-precipitate silica and aluminum compounds, drying, and calcining under the conditions described later. In addition, by pulverizing the above-mentioned mixture sol using a spray dryer, or by drying the above-mentioned mixture sol and granulating the gel, an aluminum-containing silica having a desired particle size can also be prepared. The carrier of the composition.

Regarding the preparation method of the carrier containing silica, alumina, and an oxide of at least one alkali metal among alkali metals, alkaline earth metals, and rare earth metals, the above-mentioned aluminum-containing dioxide containing silica and alumina can be prepared. The preparation method of the carrier of the silicon-based composition is carried out by drying the slurry obtained by mixing alkali metal compounds, alkaline earth metal compounds and/or rare earth metal compounds with silicon dioxide and aluminum components, and then performing the following conditions. Prepared by roasting.

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

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

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

Specific examples of the inorganic substances used include inorganic acids such as nitric acid, hydrochloric acid, and sulfuric acid; alkali metals such as Li, Na, K, Rb, and Cs; and metal salts of alkaline earth metals such as Mg, Ca, Sr, and Ba; and Water-soluble compounds such as ammonia and ammonium nitrate; and clay minerals that form suspensions when dispersed in water. Moreover, as a specific example of an organic substance, polymers, such as polyethylene glycol, methyl cellulose, polyvinyl alcohol, polyacrylic acid, and polyacrylamide, can be mentioned.

The effects of adding inorganic and organic substances are various. The main effects are 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 adjusting the viscosity and solid content concentration with inorganic or organic matter, it can be changed into a liquid that is easy to obtain a spherical carrier. In addition, the control of the pore diameter and the pore volume can be implemented by a multi-stage hydrothermal synthesis step of the mixed slurry described later. In addition, it is also preferable to appropriately select and use an optimum organic compound which remains in the interior of the carrier during the molding stage and can be removed by baking and washing after molding.

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

The preferred manufacturing method of the catalyst for carboxylate manufacturing of the present embodiment includes: step I, which is to spray dry the mixed slurry in a dryer by means of a rotating disc; step II, which is to spray-dry the obtained The product is calcined to obtain a carrier; and step III, which is to support the catalyst metal particles on the carrier. Furthermore, in the method for producing a catalyst for producing a carboxylate according to the present embodiment, in the above-mentioned step 1, the feeding amount of the mixed slurry to be sprayed with respect to the lateral radius of the spray dryer is 5×10 ⁻³ m ² /Hr or more and 70×10 ^-3 m ² /Hr or less, and the peripheral speed of the disk is 10 m/s or more and 120 m/s or less. According to the above method, the bulk density and particle size distribution of the catalyst for carboxylate production of the present embodiment are easily obtained within the predetermined ranges, and the catalyst for carboxylate production which suppresses the outflow of the catalyst and exhibits high activity can be obtained.

When preparing the mixed slurry used in the step I in this embodiment, for example, the stirring operation of the raw material mixed liquid can be performed while appropriately 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 for liquidizing the mixed slurry into droplets, a known spraying device such as a rotating disk method, a two-fluid nozzle method, and a pressurized nozzle method can be used.

The liquid to be sprayed (mixed slurry) is preferably used in a well-mixed state (a state in which each component is sufficiently dispersed). In the case of a good mixed state, there is a tendency to reduce adverse effects on carrier performance, such as a decrease in durability due to the presence of segregation of each component. In particular, when the raw material mixture is prepared, the viscosity of the slurry may increase and local gelation (condensation of the colloid) may occur, and there may be concerns about the formation of non-uniform particles. Therefore, it is sometimes preferable to perform 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 an alkali. modulation.

The liquid (mixed slurry) to be sprayed preferably has a certain degree of viscosity and solid content concentration. When the viscosity and the solid content concentration are above a certain level, it is possible to prevent the porous body obtained by spray drying from becoming a concave sphere instead of a true sphere. In addition, 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 viscosity change (final ⊿ viscosity) in 1 hour from the start of spray drying (the state of the raw material mixed solution) to the spraying (the state of the mixed slurry) is related to the particle size distribution and bulk density obtained by spray drying. Tendency to influence. From the above viewpoint, the final ⊿ viscosity is preferably less than 10 mPa·s/Hr, more preferably 7 mPa·s/Hr or less, and still more preferably 5 mPa·s/Hr or less. The lower limit value of the final ⊿ viscosity is not particularly limited, but is, for example, 0 mPa·s/Hr or more. The final ⊿ viscosity can be measured based on the method described in the examples described later. In addition, the solid content concentration is preferably in the range of 10 to 50 mass % in view of the shape, bulk density, and particle size. 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 3 m/s or more and 9 m/s or less, more preferably 4 m/s or more8 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 the rotary disk method in the dryer, the following conditions are preferable. The drier of the rotary disk system includes, for example, a disk such as an atomizer. The mixed slurry can be sprayed with the disc, and the bulk density and particle size distribution of the dried product can be adjusted. Specifically, the feeding amount of the liquid to be sprayed with respect 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 or more and 50 × 10 ^-3 m ² /Hr or less, more preferably 20 × 10 ^-3 m ² /Hr or more and 40 × 10 ^-3 m ² /Hr or less. Further, the peripheral speed of the disk is preferably 10 m/s or more and 120 m/s or less, more preferably 20 m/s or more and 100 m/s or less, and still more preferably 30 m/s or more and 90 m/s or less.

The calcination temperature of the carrier is usually selected from the range of 200-800°C. When the calcination is performed at a temperature exceeding 800°C, the specific surface area tends to decrease significantly, which is not preferable. In addition, the calcination environment is not particularly limited, and the calcination is usually carried out in air or nitrogen. In addition, the calcination time can be determined according to the specific surface area after calcination, and is usually 1 to 48 hours. Since the calcination conditions change the physical properties of the carrier such as porosity, it is necessary to select appropriate temperature conditions and heating conditions. If the calcination temperature is too low, it tends to be difficult to maintain durability as a composite oxide, and if it is too high, the pore volume may decrease. In addition, it is preferable to raise temperature gradually by the temperature rise condition etc. as a temperature rise condition. When calcined under abruptly high temperature conditions, the vaporization and combustion of inorganic and organic substances become violent, and exposure to a high temperature state above the setting will become a cause of 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 classification apparatus, a sieve, a vibrating screen, an inertial classifier, a forced vortex centrifugal classifier, a free vortex classifier, such as a cyclone, etc. are mentioned, for example.

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

If the pore diameter of the carrier is less than 3 nm, the exfoliation properties of the supported metal tend to be good, but when it is used as a catalyst in a liquid-phase reaction, etc., the diffusion resistance in the pores is not so large that the reaction does not occur. The pore diameter is preferably 3 nm or more from the viewpoint of rate-limiting the diffusion process of the raw material to maintain high reactivity. On the other hand, from the viewpoint of the difficulty of cracking the support and the difficulty of peeling off the supported metal, it is preferably 50 nm or less. Therefore, the pore diameter of the carrier is preferably 3 nm to 50 nm, more preferably 3 nm to 30 nm. Pore volume is necessary for the presence of pores to support composite nanoparticles. However, when the pore volume increases, the strength tends to drop sharply. Therefore, the pore volume is preferably in the range of 0.1 to 1.0 mL/g, and more preferably in the range of 0.1 to 0.5 mL/g, from the viewpoint of strength and supporting properties. The carrier of this embodiment preferably has both the pore diameter and the pore volume satisfying the above-mentioned ranges.

The shape of the carrier is based on the reaction form. In the fixed bed, the hollow cylindrical shape and honeycomb shape with less pressure loss are selected. In the liquid slurry suspension condition, the spherical shape is usually selected, and the best 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 generally used, the particle size is preferably 10-200 μm, more preferably 20-150 μm, and more preferably 10-200 μm according to the balance with the reaction characteristics. 30 ~ 150 μm particle size. In the cross-filter method, small particles of 0.1 to 20 μm or less are preferred because of their higher reactivity. In accordance with this purpose of use, it can be used as a catalyst for chemical synthesis by changing its type and form.

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

Furthermore, in the present embodiment, the atomic ratio of nickel and/or cobalt to the constituent elements of the above-mentioned carrier has a preferable range. When the carrier comprising the aluminum-containing silica-based composition containing silicon dioxide and aluminum oxide in this embodiment is used, the composition ratio of nickel or cobalt and aluminum oxide in the catalyst is the atomic ratio of Ni/Al or The Co/Al atomic ratio is preferably 0.01 to 1.0, more preferably 0.02 to 0.8, and still more preferably 0.04 to 0.6. Furthermore, when a carrier containing silica, alumina, and an oxide of at least one alkali metal among alkali metals, alkaline earth metals and rare earth metals is used, the composition of nickel or cobalt in the carrier and alumina In terms of Ni/Al atomic ratio or Co/Al atomic ratio, the ratio is preferably 0.01 to 1.0, more preferably 0.02 to 0.8, further 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 or basic metal oxide as a carrier constituent element is within the above-mentioned range, the effect of improving the elution of nickel and/or cobalt and the structural change of the carrier particles may become greater. tendency. The reason for this is considered to be that within the above range, nickel and/or cobalt, aluminum, and basic metal oxides form specific complex oxides, thereby forming a stable bond structure.

The catalyst for carboxylate production of the present embodiment may contain a third component element in addition to nickel and/or cobalt and X in an oxidized state 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 in the carrier is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass. In addition, the catalyst for carboxylate production may contain at least one metal component selected from alkali metals, alkaline earth metals, and rare earth metals. The content of alkali metals, alkaline earth metals and rare earth metals in the carrier is preferably selected from a range of 15% by mass or less.

Furthermore, these third component elements, 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 the reactivity and the difficulty of desorption of the active ingredient, the specific surface area of the catalyst for carboxylate production of the present embodiment is preferably 20 to 350 m ² /g in the measurement by the BET nitrogen adsorption method, and more The range is preferably 50 to 300 m ² /g, and more preferably 100 to 250 m ² /g.

The pore diameter of the catalyst for the production of carboxylate is derived from the pore structure of the carrier, and if it is less than 3 nm, the exfoliation properties of the supported metal component tend to be good. 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 high reactivity. On the other hand, from the viewpoint of the difficulty of breaking the supported material and the difficulty of peeling off the supported composite particles, it is preferably 50 nm or less. Therefore, the pore diameter of the catalyst for carboxylate production is preferably 3 nm to 50 nm, more preferably 3 nm to 30 nm, and still more preferably 3 nm to 10 nm. 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, from the viewpoint of the supporting properties and the reaction properties. In the catalyst for carboxylate production of the present embodiment, it is preferable that both the pore diameter and the pore volume satisfy the above-mentioned ranges.

[Production method of catalyst for carboxylate production] It does not specifically limit as a manufacturing method of the catalyst for carboxylate manufacturing of this embodiment, The following preferable steps can be included. Hereinafter, each step will be described.

As the first step, an aqueous slurry containing a carrier supporting an oxide of at least one alkali metal selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals, and a carrier 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) with an acidic aqueous solution of a soluble metal salt 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 catalyst precursor for producing a carboxylate in which nickel and/or cobalt and component X are precipitated on the carrier is generated.

Next, as a second step, if necessary, the precursor obtained in the first step is washed with water, dried, and then heat-treated, whereby a catalyst for carboxylate production can be obtained.

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

In the present embodiment, it is preferable to carry out aging in which the carrier supporting the oxide of at least one alkali metal selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals is matured in water before the first step. step. By pre-aging the carrier, a more distinct distribution layer of composite particles can be obtained. The effect of aging of the carrier is presumed to be caused by the rearrangement of the pore structure of the carrier, resulting in a more uniform and clear pore structure, based on the results of the pore distribution measurement by the nitrogen adsorption method. The aging temperature of the carrier can also be room temperature, but the change of the pore structure is relatively slow, so it is preferably selected from a temperature higher than room temperature, that is, in the range of 60-150°C. In the case of carrying out under normal pressure, the range of 60-100 degreeC is preferable. In addition, the time of the aging treatment varies depending on the temperature conditions, but in the case of, for example, 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, after the carrier is matured, the carrier can be dried and calcined before being used. The acidic aqueous solution of the soluble metal salt is contacted, so that nickel and/or cobalt and X component are insoluble and immobilized on the carrier.

As the soluble metal salt containing nickel used in the preparation of the catalyst, nickel nitrate, nickel acetate, nickel chloride and the like can be exemplified. In addition, as the soluble metal salt containing X, for example, when palladium is selected as X, palladium chloride, palladium acetate, etc. can be cited; when ruthenium is selected, ruthenium chloride, ruthenium nitrate, etc. can be cited; when gold is selected In the case of chloroauric acid, sodium gold chloride, potassium dicyanophosphate, diethylamine gold trichloride, gold cyanide, etc., in the case of selecting silver, silver chloride, silver nitrate, etc. can be exemplified.

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, and more preferably 0.005-0.2 mol/L. The ratio of nickel or cobalt to 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 at which the carrier is brought into contact with an acidic aqueous solution containing soluble metal salts of nickel and/or cobalt and X is one of the important factors for controlling the distribution of the composite particles, and is selected from alkali metals, alkaline earth metals and The amount of the oxide of at least one alkali metal in the group of rare earth metals varies, but if the temperature is too low, the reaction tends to be slow and the distribution of the composite particles tends to expand. In the production method of the present embodiment, from the viewpoint of obtaining a support layer in which the composite particles are more clearly localized, the temperature at the time of contact with an acidic aqueous solution containing a soluble metal salt of nickel and/or cobalt and X is: If the temperature at which a higher reaction rate can be obtained, it is preferably 60°C or higher, more preferably 70°C or higher, further preferably 80°C or higher, particularly preferably 90°C or higher. As long as the temperature of the liquid obtained by mixing the acidic aqueous solution and the water slurry is 60°C or higher, the water slurry can be heated in advance to the extent that the mixed solution 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 60°C or higher in advance.

The reaction can also be carried out under pressure and at a temperature above the boiling point of the solution, but it is usually preferably carried out at a temperature below 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 it varies depending on the type of carrier, the supported amount and ratio of nickel and/or cobalt and X, and the like, but is usually 1 minute to 5 minutes. hours, preferably 5 minutes to 3 hours, more preferably 5 minutes to 1 hour.

The production method of the catalyst for carboxylate production of the present embodiment is based on the principle of oxidation of at least one alkali metal selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals supported on a carrier in advance. It reacts with soluble metal salts containing nickel and/or cobalt and X to make nickel and/or cobalt and X component insoluble and immobilized. In order to make the composite of nickel and/or cobalt and X component more sufficient, it is preferable to simultaneously immobilize from a mixed aqueous solution of the two components.

Further, in the production method of the present embodiment, the aqueous slurry containing the carrier supporting at least one oxide of an alkali metal selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals preferably contains an oxide selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals. Alkaline metal salts 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 complexation of nickel and/or cobalt and X can be promoted, and the distribution of complex particles can be controlled more precisely. The reason for this effect is presumed to be that by adding a metal salt of at least one selected from the group consisting of alkali metals, alkaline earth metals and rare earth metals to the aqueous solution, the alkali metal preliminarily supported on the carrier is controlled to be controlled The rate of chemical reaction with oxides, soluble metal salts containing nickel and/or cobalt and X.

As at least one basic metal salt selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals, water-soluble salts such as organic acid salts of these metals, inorganic salts such as nitrates, and chlorides can be used. 1 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 described above varies depending on the amounts and ratios of nickel and/or cobalt and component X, and is determined by preloading It is determined by the amount of basic metal oxide in the carrier. Usually, it is 0.001-2 times mol with respect to the amount of nickel and/or cobalt and X component in an aqueous solution, Preferably it is 0.005-1 times mol.

Further, the aqueous slurry containing the carrier supporting the oxide of at least one alkali metal selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals preferably 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 support layer in which the composite particles are locally present. 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 supported on the carrier in advance, and nickel and/or cobalt are consumed. The reaction place with X further fixes the above-mentioned basic metal oxide, nickel and/or cobalt, and X component inside by the reaction.

The amount of the aluminum component varies depending on how many μm the thickness of the layer not supporting nickel and/or cobalt and the X component is to be set, and is determined by the amount of the basic metal oxide previously supported on the carrier. Usually, it is 0.001 to 2 moles, preferably 0.005 to 1 mole, with respect 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 rate in the body and the rate of insolubilization of the component by chemical reaction are well balanced, so that the composite particles can be immobilized in an extremely narrow area near the surface of the carrier.

In addition, in the case where an outer layer substantially free of composite particles is formed on the outer surface of the carrier, it is presumed as follows: when aluminum is allowed to react with the alkali metal component near the outer surface of the carrier, the components that can interact with the outer surface of the carrier are consumed. When nickel and/or cobalt and X component react with basic metal components, and then support nickel and/or cobalt and X, the reactive basic metal components near the outer surface of the support have been consumed, so nickel and/or cobalt and X are consumed. /or cobalt and X are immobilized by reacting with basic metal oxides inside the support.

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 to 900°C, preferably 80 to 800°C, more preferably 200 to 700°C, and still more preferably 300 to 600°C.

Heat treatment in an 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 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 second step, reduction treatment can also be performed in a reducing environment (hydrogen, hydrazine, formalin, formic acid, etc.) as needed. In this case, the nickel and/or cobalt in the oxidized state is selected to be not completely reduced to the metallic 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 used in air (or in the atmosphere) or in an oxidizing environment (oxygen, ozone, nitrogen oxides, carbon dioxide, hydrogen peroxide, hypochlorous acid, inorganic/organic peroxides as needed) oxides, etc.) for oxidation treatment. The temperature and time in this case are appropriately selected according to the type of the oxidant, the type of X, and the amount of the catalyst.

The third component elements other than nickel and/or cobalt and X may be added during the preparation of the support or under the 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 metals, alkaline earth metals, and rare earth metals are selected from organic acid salts, inorganic acid salts, hydroxides, and the like.

[Production method of carboxylate] The catalyst for carboxylate production of the present embodiment can be widely used as a catalyst for chemical synthesis. For example, it can be used for carboxylate formation reaction between aldehyde and alcohol, and carboxylate formation reaction from alcohols. That is, the method for producing a carboxylate according to the present embodiment may include the steps of: (a) reacting an aldehyde with an alcohol in the presence of a catalyst for producing a carboxylate according to the present embodiment and oxygen, or (b) reacting an aldehyde with an alcohol. One or two or more alcohols are reacted.

The catalyst for carboxylate production of the present embodiment exhibits an excellent effect especially when used as a catalyst for an oxidation reaction. As the reaction raw material 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, olefins, Alcohols, ketones, aldehydes, ethers, aromatic compounds, phenols, sulfur compounds, phosphorus compounds, oxygen-containing nitrogen compounds, amines, carbon monoxide, water, etc. These reaction raw material materials can be used individually or as a mixture containing 2 or more types. Oxidation products such as various oxygen-containing compounds, oxidative adducts, oxidative dehydrogenates and the like which are industrially useful are obtained from these reaction raw materials.

As the reaction raw material, specifically, as alkanes, for example, methane, ethane, propane, n-butane, isobutane, n-pentane, n-hexane, 2-methylpentane, 3-methyl pentane, Aliphatic alkanes such as cyclopentane; alicyclic alkanes such as cyclopentane, cyclohexane, cycloheptane, cyclooctane, etc.

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

Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2nd butanol, 3rd butanol, n-pentanol, n-hexanol, n-heptanol, allyl alcohol, croton Saturated and unsaturated aliphatic alcohols such as alcohols; saturated and unsaturated alicyclic alcohols such as cyclopentanol, cyclohexanol, cycloheptanol, methylcyclohexanol, cyclohexen-1-ol; ethylene glycol, propylene glycol , 1,3-propanediol, 1,3-butanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol and other aliphatic and alicyclic polyols; 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. ; Benzaldehyde (benzaldehyde), methyl benzaldehyde, benzyl aldehyde (benzilaldehyde), phthalaldehyde and other aromatic aldehydes and derivatives of these aldehydes.

Examples of ketones include aliphatic ketones such as acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, and methyl propyl ketone; cyclopentanone, cyclohexanone, cyclooctanone, 2 - Alicyclic ketones such as methylcyclohexanone and 2-ethylcyclohexanone; aromatic ketones such as acetophenone, propiophenone, benzophenone, and the like.

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 sulfonyl group, or the like can be mentioned.

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

As a sulfur compound, thiols, such as methyl mercaptan, ethane mercaptan, propane mercaptan, benzyl mercaptan, thiophenol, etc. are mentioned.

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

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

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

Examples of aldehydes used as raw materials include C ₁ to C ₁₀ aliphatic saturated aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, and glyoxal; ₃ - _C10 aliphatic α,β-unsaturated aldehydes; _C6 - _C20 aromatic aldehydes such as benzaldehyde, methyl benzaldehyde, benzyl aldehyde, phthalaldehyde; and derivatives of these aldehydes. These aldehydes can be used alone or as a mixture of any two or more. In this embodiment, the aldehyde is preferably selected from acrolein, methacrolein, or a mixture thereof.

Examples of alcohols include _C1 - _C10 aliphatic saturated alcohols such as methanol, ethanol, isopropanol, butanol, 2-ethylhexanol, and octanol; _C5 -C10 aliphatic alcohols such as cyclopentanol and cyclohexanol. C ₁₀ alicyclic alcohols; C ₂ to C ₁₀ diols such as ethylene glycol, propylene glycol, butylene glycol; C 3 to C 10 aliphatic unsaturated alcohols such as allyl alcohol and methallyl alcohol; C ₃ to C ₁₀ aliphatic unsaturated alcohols such as benzyl alcohol ₆ -C ₂₀ aromatic alcohols; hydroxy oxetanes such as 3-alkyl-3-hydroxymethyl oxetane. These alcohols may be used alone or as a mixture of any two or more. In this embodiment, it is preferable that the aldehyde is acrolein and/or methacrolein, and the alcohol is methanol.

The amount ratio of aldehyde to alcohol is not particularly limited. For example, the molar ratio of aldehyde/alcohol can be implemented in a wide range of 10 to 1/1,000, but is usually 1/2 in molar ratio. Implement within the range of ~1/50.

The amount of the catalyst used can be greatly changed according to the type of reaction raw materials, the composition and preparation method of the catalyst, the reaction conditions, the reaction form, etc., and is not particularly limited. When the catalyst is reacted in a slurry state, the The solid content concentration in the slurry is preferably used in a range of 1 to 50 mass/volume %, more preferably 3 to 30 mass/volume %, and still more preferably 10 to 25 mass/volume %.

In the manufacture of the carboxylate, any method such as a gas phase reaction, a liquid phase reaction, and a trickle reaction can be used, and it can be implemented by any method of a batch method or a continuous method.

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

The reaction form can also utilize previously known forms such as a fixed bed type, a fluidized bed type, and a stirred tank type. For example, when it is implemented in a liquid phase, any reactor form such as a bubble column reactor, a draft tube type reactor, and a stirred tank reactor can be used.

The oxygen used in the production of carboxylate can be molecular oxygen, that is, oxygen itself or a mixed gas obtained by diluting oxygen with a diluent that is inert to the reaction, such as nitrogen, carbon dioxide gas, etc. From the viewpoint of economical efficiency, etc., air is preferably used.

The oxygen partial pressure varies according to the reaction raw materials such as aldehyde species and alcohol species, the reaction conditions or the type of the reactor. In practice, the oxygen partial pressure at the outlet of the reactor becomes the concentration range below the lower limit of the explosion range. For example, it is better to manage the oxygen partial pressure. 20 to 80 kPa. Regarding the reaction pressure, it can be carried out in any wide pressure range from reduced pressure to under increased pressure, and it is usually carried out under the pressure in the range of 0.05 to 2 MPa. Also, from the viewpoint of safety, it is preferable to set the full pressure (eg, oxygen concentration of 8%) so that the oxygen concentration of the gas flowing out of the reactor does not exceed the explosion limit.

When the production reaction of carboxylate is carried out in a liquid phase or the like, it is preferable to add an alkali metal or alkaline earth metal compound (for example, oxide, hydroxide, carbonate, carboxylate) to the reaction system to react. The pH 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 the carboxylate can be carried out at a high temperature of 200°C or higher, but is preferably 30 to 200°C, more preferably 40 to 150°C, and still more preferably 60 to 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, the present embodiment will be described more specifically with reference to examples, but the present embodiment is not limited to these examples at all.

In the following Examples and Comparative Examples, various physical property measurements were carried out by the following methods.

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

[Determination of the supported amount of Ni and X and the atomic ratio of Ni/X] The concentrations of nickel and X in the composite particles were quantified using IRIS Intrepid II XDL type ICP (Inductively Coupled Plasma, Inductively Coupled Plasma) luminescence analyzer (ICP-AES, MS) manufactured by Thermo Fisher Scientific. The preparation of the sample is to weigh the supported material into a decomposition vessel made of Teflon, add nitric acid and hydrofluoric acid, and use the ETHOS TC microwave decomposition device manufactured by Milestone General K.K. After heating and decomposing, it is evaporated and dried on a heater. Then, nitric acid and hydrochloric acid are added to the precipitated residue, and pressure decomposition is carried out by a microwave decomposition apparatus, and the obtained decomposed solution is fixed with pure water as a test solution. The quantification method is to quantify by the internal standard method of ICP-AES, to obtain the nickel and X content in the catalyst by subtracting the operation blank value performed at the same time, and to calculate the supported amount and the atomic ratio.

[Analysis of Crystal Structure of Composite Particles] Using the Rint2500 powder X-ray diffraction apparatus (XRD) manufactured by Rigaku Corporation, in the X-ray source Cu tube (40 kV, 200 mA), the measurement range is 5 ~ 65 deg (0.02 deg/step), and the measurement speed is 0.2 deg/ min, the slit width (scattering, diffusing, receiving light) is 1 deg, 1 deg, 0.15 mm. The sample is uniformly spread on the non-reflective sample plate and fixed with neoprene.

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

[Analysis of the chemical state of nickel] The NiKα spectrum was measured using an XFRA190 dual-crystal type high-resolution X-ray fluorescence analyzer (HRXRF) manufactured by Technos, and the obtained parameters were compared with those of the standard materials (nickel metal, nickel oxide), and it was estimated that the The chemical state such as the valence of nickel in the carrier. The measurement sample is used for measurement as it is. The determination of the Kα spectrum of Ni was carried out in partial spectral mode. At this time, Ge(220) was used as the spectroscopic crystal, the slit with a vertical divergence angle of 1° was used, and the excitation voltage and current were set to 35 kV and 80 mA, respectively. In addition, a filter paper was used as an absorber for a standard sample, and a count time was selected for each sample for a supported sample, and the measurement was performed so that the peak intensity of the Kα spectrum was 3,000 cps or less and 10,000 counts or more. The measurement of each sample was repeated 5 times, 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 to 5 times), the peak position, full width at half maximum (FWHM), and asymmetry coefficient (AI) were calculated, and the peak position was 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) [accelerating voltage 300 kV, with an energy dispersive X-ray detector (EDX)] manufactured by JEOL Corporation. , STEM dark field image, STEM-EDS composition analysis (point analysis, mapping, line analysis). Data analysis software system uses TEM image, STEM image analysis (length measurement, Fourier transform analysis): DigitalMicrographTM Ver.1.70.16, Gatan, EDS Data analysis (mapped image processing, composition quantitative calculation): NORAN System SIX ver.2.0, Thermo Fisher Scientific. The measurement sample was ground with a mortar and then dispersed in ethanol, ultrasonically washed for about 1 minute, dropped onto Mo-made abrasive sand, and air-dried to serve as a sample for TEM/STEM observation.

[Measurement of UV-Vis Spectroscopic Spectrum of Composite Particles] Using the V-550 UV-Vis spectrophotometer (UV-Vis) (with integrating sphere unit and powder sample holder) manufactured by Japan Spectrophotometer, 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 supported material was set in a holder for powder samples and used for UV-Vis measurement.

[Shape observation of carrier and catalyst for carboxylate production] The carrier and the catalyst for carboxylate production were observed using an X-650 scanning electron microscope (SEM) manufactured by Hitachi, Ltd.

[Measurement of D ₁₀ , D ₅₀ , D ₉₀ and half width W of the catalyst for the production of carboxylate] Take 0.2 g of the catalyst into a beaker, add 16 mL of purified water, and then use a product manufactured by SONIC & MATERIALS.INC. A sample for measurement was prepared by performing dispersion treatment for 1 minute in a VCX130 ultrasonic disperser. For the sample for measurement, the particle size distribution of the volume-based particle size distribution of the catalyst for carboxylate ester production was measured using an LS230 laser diffraction-scattering particle size distribution analyzer manufactured by Beckman Coulter Co., Ltd., and the cumulative frequency was x%. _Dx (D ₁₀ , D ₅₀ and D ₉₀ ) and half width W of 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 Manufacture of Carboxylic Acid Esters] As a pretreatment, about 120 g of the catalyst for carboxylate production was taken into a stainless steel crucible, and dried in a muffle furnace at 150° C. for 6 hours. After calcination, it was added to a desiccator (with silica gel added) and cooled to room temperature. Then, 100.0 g of the pretreated catalyst for carboxylate production was transferred to a 250 mL graduated cylinder, and the graduated cylinder was tapped and filled with a shaker for 15 minutes. Thereafter, the surface of the sample in the graduated cylinder is flattened and the fill volume is read. The bulk density is a value obtained by dividing the mass of the catalyst for carboxylate production by the filling volume.

[outflow rate] The outflow rate was calculated by the following formula based on the total amount of the catalyst used for the production of the carboxylate described later, and the amount of the catalyst remaining after the production of the carboxylate for 500 hours. Elution rate = {1 - (amount of remaining catalyst/amount of catalyst used in the reaction)}×100[%] Here, the residual catalyst amount is the catalyst mass obtained by drying the catalyst for carboxylate production after carrying out the production of carboxylate for 500 hours at 130°C 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 supplied for the reaction decreases in a long-term operation, so that the conversion rate tends to deteriorate as a result.

[Example 1] (Production of Catalyst for Carboxylic Ester Production) An aqueous solution obtained by dissolving 3.75 kg of aluminum nitrate nonahydrate, 2.56 kg of magnesium nitrate, and 540 g of 60 mass % nitric acid in 5.0 L of pure water was slowly dropped. To 20.0 kg of a silica sol solution (SiO ₂ content of 30 mass %) with a colloidal particle size of 10 to 20 nm in a stirred state maintained at 15° C., the pH was adjusted to pH=1.8. The raw material mixed liquid (solid content: 25 mass %) containing the silica sol, aluminum nitrate, and magnesium nitrate obtained in this way was heated up to 55 degreeC. Then, the raw material mixture was stirred at a speed of 5.5 m/s at the tip of the stirring blade for 30 hours to obtain a mixed slurry with a final Δ viscosity of 0.5 mPa·s/Hr. After that, the slurry was fed in such a manner that the feed amount/SD radius was 25×10 ^-3 [m ² ] by using a spray dryer device under the condition of a disk (atomizer) peripheral speed of 80 m/s. Spray-dried to obtain a solid. Furthermore, the SD radius refers to the lateral radius of the spray dryer of the rotary disk method used in this embodiment. Next, the obtained solid matter with a thickness of about 1 cm was filled in a stainless steel container opened at the top, and the temperature was raised from room temperature to 300° C. in an electric furnace for 2 hours, and then kept for 3 hours. Furthermore, the temperature was raised to 600° C. over 2 hours, the temperature was maintained for 3 hours, and then slowly cooled to obtain a carrier. The obtained carrier contained 83.3 mol %, 8.3 mol % and 8.3 mol % of silicon, aluminum and magnesium with respect to the total molar amount of silicon, aluminum and magnesium, respectively. In addition, according to the observation by 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, the prepared aqueous solution containing 16.35 g of nickel nitrate hexahydrate and 12 mL of 1.3 mol/L aqueous solution of chloroauric acid and heated to 90 °C was added to the above-mentioned carrier slurry, and further stirred at 90 °C for 30 minutes, and The nickel and gold components are insoluble and immobilized on the carrier. Then, after standing still, removing the supernatant, and washing with distilled water several times, it filtered. After drying at 105° C. for 10 hours with a dryer, it was calcined in air at 450° C. in a muffle furnace for 5 hours to obtain a contact for carboxylate production supporting 1.05 mass % of nickel and 0.91 mass % of gold. A medium (NiOAu/SiO ₂ -Al ₂ O ₃ -MgO composite particle support). The Ni/Au atomic ratio of the obtained catalyst for carboxylate production was 4.0. With respect to a sample obtained by embedding the obtained composite particle-supporting material in a resin and grinding it, line analysis of particle cross-section was performed 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 Composite particles are not present. Next, the morphology of the above-mentioned composite particle-supported material was observed with a transmission electron microscope (TEM/STEM), and as a result, it was confirmed that the particles supported on the support had a maximum distribution (number average particle diameter: 3.0 nm) between 2 and 3 nm. Spherical nanoparticles. If the nanoparticles were further magnified, lattice fringes corresponding to the interplanar spacing of Au(111) were observed in the nanoparticles. The composition point analysis by STEM-EDS was performed on each nanoparticle, and 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 nanodomain analysis of the observed particles was carried out. As a result, the atomic ratio of Ni/Au in the central part of the particle was 0.90, and that in the edge part of the particle was 2.56. In the part other than the particles, only a trace amount of nickel was detected. When the same measurement was performed at 50 locations, a large amount of nickel was detected around the edge portion of any particle. According to the EDS elemental mapping, the distribution of nickel and gold is observed to be roughly the same. In addition, 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), a diffraction pattern derived from nickel was not observed, and it was confirmed that it existed in an amorphous state. On the other hand, although it cannot be described as a clear peak, there is a broad peak equivalent to gold crystals. Although the value is close to the detection limit (2 nm) of powder X-ray diffraction, the average crystallite diameter is about 3 nm when calculated by Scherrer's formula. Regarding the chemical state of nickel, it was confirmed that nickel is divalent from the results of X-ray photoelectron spectroscopy (XPS). According to the results of double-crystal high-resolution X-ray fluorescence analysis (HRXRF), the chemical state of nickel is presumed to be high-spin 2 valence of nickel, and based on the difference in NiKα spectrum, it is clear that the chemical state is different from that of nickel oxide, which is a single compound. . The NiKα spectrum of the catalyst obtained from the measured spectrum has a full width at half maximum (FWHM) of 3.470 and a chemical shift (ΔE) of 0.335. The NiKα spectrum of nickel oxide measured as a standard material had a full width at half maximum (FWHM) of 3.249 and a chemical shift (ΔE) of 0.344. In addition, the change of the electronic excitation state of the composite particle support was studied by ultraviolet-visible spectroscopy (UV-Vis), and the result showed that there was no surface plasmon absorption peak originating from gold nanoparticles near 530 nm, but at 200 nm. Broad absorption due to NiO ₂ 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 Manufacture of Carboxylate) The specific surface area of the obtained catalyst for 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 of the catalyst for carboxylate production by the laser-scattering method. As a result, the half width W of the particle size distribution was 50 μm, and D ₅₀ , D ₁₀ /D ₅₀ , The values of D ₉₀ /D ₅₀ and W/D ₅₀ were 60 μm, 0.7, 1.5, and 0.8, respectively. The particle size distribution is a single peak. Moreover, when the bulk density was measured, it was 1.05 g/cm ³ .

(Production of carboxylate) 240 g of the obtained catalyst for producing carboxylate 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 at the front end of the stirring blade was The contents were stirred at a speed of 4 m/s, while the reaction of forming an oxycarboxylate from an aldehyde and an alcohol was carried out. That is, 36.7 mass % of methacrolein/methanol solution was continuously supplied to the reactor at 0.6 L/hr, and 1 to 4 mass % of NaOH/methanol solution was continuously supplied to the reactor at 0.06 L/hr, and the reaction temperature was 80° C. Air was blown under 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 value of the reaction system was 7. The reaction product was continuously discharged from the reactor outlet due to overflow, and was analyzed by gas chromatography to study the reactivity. The conversion of methacrolein for 500 hours from the start of the reaction was 72%, and the selectivity of methyl methacrylate was 95%. In addition, 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 in which aluminum nitrate nonahydrate and magnesium nitrate are dissolved in the raw material mixed solution, the amount of solid content is adjusted to the value shown in Table 1, (ii) by The amount of 60 mass % nitric acid was increased and decreased, and the pH value was adjusted so that it may become the value of Table 1. The physical properties of the catalyst for producing carboxylate were evaluated in the same manner as in Example 1, and further, carboxylate was produced using it in the same manner 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 to 7 is a single peak. These results are shown in Table 1.

[Table 1] Carrier manufacturing conditions Catalysts for the manufacture of carboxylate 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/Choice Rate Solid content mass % pH temperature ℃ time Hr The speed of the front end of the stirring blade 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 the manufacture of carboxylate, comprising catalyst metal particles and a carrier supporting the catalyst metal particles, wherein the bulk density of the catalyst for the manufacture of carboxylate is 0.50g/ ^cm3 or more and 1.50g/cm3 ³ or less, D ₁₀ /D ₅₀ ≧ 0.2 and D ₉₀ /D ₅₀ ≦2.5 when the particle size at which the frequency is accumulated to x% in the volume-based particle size distribution of the catalyst for the production of carboxylate is defined as D _x , W/D ₅₀ ≦1.5 when the half-height width of the particle size distribution is set as W. The catalyst for carboxylate production according to claim 1, wherein the above W is 100 μm or less. The catalyst for carboxylate production according to claim 1 or 2, wherein the catalyst metal particles contain at least one element selected from the group consisting of nickel, cobalt, palladium, platinum, ruthenium, lead, and gold, silver, and copper . The catalyst for carboxylate production as claimed in claim 1 or 2, wherein the catalyst metal particles contain nickel and/or cobalt in an oxidized state and X (X represents selected from nickel, palladium, platinum, ruthenium, gold, silver and composite particles of at least one element of the group consisting of copper). The catalyst for carboxylate production according to claim 4, wherein the composition ratio of nickel or cobalt to X in the composite particles is 0.1 to 10 in terms of Ni/X atomic ratio or Co/X atomic ratio. The catalyst for the production of carboxylate according to claim 4, wherein the composite particles contain an oxidized Nickel or Cobalt, and Gold. The catalyst for carboxylate production according to claim 4, wherein the average particle diameter of the composite particles is 2 to 10 nm. The catalyst for the production of carboxylate according to claim 4, wherein the supporting layer locally present on the composite particles is present from the surface of the catalyst for the production of the carboxylate to the catalyst for the production of the carboxylate, etc. The area up to 40% of the effective diameter. The catalyst for carboxylate production according to claim 8, wherein the equivalent diameter is 200 μm or less, and the support layer locally present on the composite particles is present from the surface of the catalyst for carboxylate production to the carboxylate The area up to 30% of the equivalent diameter of the catalyst for ester production. The catalyst for carboxylate production according to claim 4, wherein an outer layer substantially free of composite particles is provided outside the support layer where the composite particles are locally present, and the outer layer is formed with a thickness of 0.01 to 15 μm . The catalyst for carboxylate production according to claim 4, wherein the composite particle has a core containing X, and the core is coated with nickel or cobalt in an oxidized state. The catalyst for carboxylate production according to claim 1 or 2, wherein the carrier contains silica and alumina. The catalyst for carboxylate production according to claim 1 or 2, wherein the above D ₅₀ is 10 μm or more and 200 μm or less. A method for producing a carboxylate, comprising the steps of: (a) reacting an aldehyde and an alcohol in the presence of a catalyst for producing a carboxylate and oxygen as claimed in any one of claims 1 to 13, or (a) b) One or two or more kinds of alcohols are reacted. The method for producing a carboxylate according to claim 14, wherein the aldehyde is acrolein and/or methacrolein. The method for producing a carboxylate according to claim 14 or 15, wherein the aldehyde is acrolein and/or methacrolein, and the alcohol is methanol.