CN108126762B

CN108126762B - Cobalt-based catalyst for producing unsaturated carboxylic ester, preparation and carboxylic ester production

Info

Publication number: CN108126762B
Application number: CN201611088508.7A
Authority: CN
Inventors: 高爽; 李国松; 王连月; 吕迎
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2016-12-01
Filing date: 2016-12-01
Publication date: 2021-06-08
Anticipated expiration: 2036-12-01
Also published as: CN108126762A

Abstract

A cobalt-based catalyst for producing an unsaturated carboxylic acid ester, which is a catalyst used in the one-step oxidative esterification of (a) an unsaturated aldehyde with (b) an alcohol to produce a carboxylic acid ester, under the condition that oxygen is used as an oxygen source, wherein cobalt in an oxidized state and X, where X represents at least 1 element selected from the group consisting of nickel, gold, palladium, platinum, ruthenium, silver, lanthanum and copper, are supported on a carrier in a Co/(Co + X) atomic ratio range of 0.05 to 0.99.

Description

Cobalt-based catalyst for producing unsaturated carboxylic ester, preparation and carboxylic ester production

Technical Field

The invention provides a cobalt-based catalyst, a preparation method of the catalyst and a method for producing unsaturated carboxylic ester by one-step oxidation esterification reaction of unsaturated aldehyde and alcohol by using the catalyst under the condition of taking oxygen as an oxygen source.

Background art:

methyl Methacrylate (MMA) is an important polymerization monomer, can be subjected to polymerization reaction to generate polymethyl methacrylate or a multipolymer of methyl methacrylate, and is widely applied to the production fields of organic glass, polymer dispersants, coatings, medical functional materials, acrylic plastics and the like.

At present, the main processes for industrially producing methyl methacrylate include the traditional acetone cyanohydrin method, isobutylene oxidation method and the like. Compared with the acetone cyanohydrin method, the isobutene oxidation method takes refinery carbon four resources as raw materials, the byproduct is water, and the degree of greening of the reaction raw materials and the production process is remarkably improved.

The processes developed for the oxidation of isobutene mainly include a direct oxidation process (three-step process) and a direct methyl ester process (two-step process). Among them, most of the catalysts for one-step oxidation esterification of unsaturated aldehyde into unsaturated carboxylic ester in the direct methyl ester method are currently reported to be palladium-lead catalysts, such as US5969178, US6107515, EP0890569, EP0972759, JP58154534, JP8332383, JP10263399, JP20032241345, JP2003305366, and the like. However, the main active component palladium content of the catalyst in the above patents is high, and the catalyst used for reaction has the problems of low conversion rate, more byproducts, poor selectivity and the like. In order to improve the efficiency, Asahi Kasei corporation CN 101815579A, CN101835532A, CN103097296 developed a series of Au-supported catalysts for preparing methyl methacrylate by one-step oxidative esterification, the conversion rate is 40-76%, and the selectivity is about 97%. In order to further improve the reaction effect, the Asahi chemical company CN101835532 forms a NiOAu/SiO2-Al2O3-MgO catalyst with a load layer in a specific range by controlling the distribution of nickel-gold composite particles in a carrier, and the NiOAu/SiO2-Al2O3-MgO catalyst is used for the reaction, wherein the MAL conversion rate is 75.4% when the reaction is 500 hours, the MMA selectivity is 97.2%, the MAL conversion rate is 75.1% when the reaction is 2000 hours, the MMA selectivity is 97.1%, the reaction efficiency is higher, the reactivity is not changed for a long time, and the problems existing in the prior art are better solved. But the technical monopoly can not meet the market demand of China.

The invention content is as follows:

in order to fill up the technical blank in China, an Au-Co supported oxidative esterification catalyst is invented for the purpose, the proportion of the rest components in the obtained catalyst has great influence on the crystallinity of gold, and the better the crystallinity of gold is, the better the catalytic activity and the selectivity are. The catalyst is used for catalytic synthesis of methyl methacrylate, the conversion rate of methacrolein is up to 100%, the selectivity of methyl methacrylate is up to 97%, and the post-treatment cost of other by-products, namely acetal and carboxylic acid, is reduced. However, the catalyst has the problems of high Au loading capacity, unstable reaction carrier for a long time, quick loss of active components and the like.

In order to break through international technical monopoly and meet the market demand of China, the patent provides a cobalt-based catalyst for producing unsaturated carboxylic ester by adjusting components of a carrier and the proportion of the carrier to active components, and the catalyst has the advantages of low consumption of noble metals, high reaction activity, good stability and the like.

The implementation method of the invention is as follows:

1. a cobalt-based catalyst for producing an unsaturated carboxylic acid ester, which is a catalyst used in a one-step oxidative esterification reaction of (a) an unsaturated aldehyde with (b) an alcohol to produce a carboxylic acid ester, under the condition that oxygen is used as an oxygen source,

wherein cobalt and X in an oxidation state are supported on a carrier in a Co/(Co + X) atomic ratio range of 0.05 to 0.99,

wherein X represents at least 1 element selected from the group consisting of nickel, gold, palladium, platinum, ruthenium, silver, lanthanum and copper.

2. The cobalt-based catalyst for producing carboxylic acid esters according to 1, wherein the active component comprises composite nanoparticles composed of cobalt in an oxidized state and X, and the composite nanoparticles are particles in which X is a core and the surface of the core is coated with cobalt in an oxidized state.

3. The cobalt-based catalyst for production of carboxylic acid esters according to the above 2, wherein the active ingredient contains no or Co in an oxidized state alone on a carrier in addition to the composite nanoparticles supported on the carrier;

the Co in the oxidized state is preferably a cobalt oxide in which cobalt is bonded to oxygen, or a cobalt-containing composite oxide such as an oxidized compound or a solid solution of cobalt in which cobalt is bonded to X and/or 1 or more other metal elements and oxygen, or a mixture thereof.

4. The cobalt-based catalyst for producing a carboxylic acid ester according to the above 1, wherein said carrier is a silica-based composition comprising silica, magnesia, and one, two or three compounds selected from the group consisting of alumina, zirconia and a ceria metal compound; it contains relative to the total molar amount of silicon, magnesium, aluminum, zirconium and cerium

Silicon in the molar% range,

Magnesium in the molar% range,

Aluminium in the molar% range,

Zirconium in the molar% range,

Cerium in the mole% range. For example: silica-magnesia-alumina, silica-magnesia-zirconia, silica-magnesia-ceria, silica-magnesia-alumina-zirconia, silica-magnesia-alumina-ceria, and the like.

Preparation of the composite oxide carrier:

uniformly mixing a precursor of one or two or three oxides of Al2O3, ZrO2 and CeO2, a precursor aqueous solution of SiO2 and MgO at 0-80 ℃ (the preferred range is 30-50 ℃) and a certain amount of concentrated nitric acid (the concentration range is 60-85%), stirring and curing at 50-80 ℃ for 10-48h, removing water by rotary evaporation, drying and roasting to obtain the composite oxide carrier.

The precursor of SiO2 is selected from one or more of silica sol, 60-400 mesh (preferably 200-300 mesh) column chromatography silica gel, thin layer chromatography silica gel, superfine kaolin or tetraethoxysilane. The precursor of MgO is selected from one or more than two of magnesium salts such as magnesium oxalate, magnesium acetate, magnesium nitrate, magnesium chloride, magnesium hydroxide, magnesium carbonate or magnesium oxide; the precursor of Al2O3 is one or more of aluminum salts such as aluminum hydroxide, ammonium aluminum carbonate, ammonium aluminum sulfate, aluminum bicarbonate, aluminum nitrate or aluminum trichloride; the precursor of ZrO2 is selected from one or more of zirconium salts such as zirconium hydroxide, zirconium nitrate, zirconium acetate, zirconium oxalate, zirconium oxychloride, etc.; the CeO2 precursor is one or two of cerium nitrate and ammonium cerium nitrate.

5. As described above

Any one of the cobalt-based catalysts for production of a carboxylic acid ester is characterized in that: the mass content of the active component Co accounts for 0.01-30% of the whole catalyst, and the preferred mass percentage range is 0.05-15%.

6. As described above

Any of the cobalt-based catalysts for production of carboxylic acid esters has a specific surface area of

The maximum frequency of pore diameters is

Pore volume of

Having a particle diameter of

7. As described above

Any of the cobalt-based catalysts for producing a carboxylic acid ester may be in the form of powder, granules, blocks, spheres, columns or other forms.

8. A method for producing a cobalt-based catalyst for producing a carboxylic acid ester, comprising the steps of:

a step 1 of preparing an aqueous solution of a soluble metal salt containing cobalt and X, wherein X represents at least 1 element selected from the group consisting of nickel, gold, palladium, platinum, ruthenium, silver, lanthanum and copper, and depositing cobalt and X components on a carrier to obtain a catalyst precursor;

in the 2 nd step, the obtained catalyst precursor is heat-treated to thereby bring cobalt into an oxidized state. The catalyst precursor is calcined in the atmosphere of hydrogen, oxygen, air, nitrogen or argon, preferably in the atmosphere of air; the temperature rise mode can be temperature programming or constant temperature, the temperature is 800 ℃ at 200-.

9. The process for producing a cobalt-based catalyst for producing a carboxylic acid ester as described in the above 8, wherein the process for producing the catalyst is not limited, and examples thereof include an impregnation method or a uniform precipitation method, preferably a uniform precipitation method;

wherein, the precipitant parent substance used in the uniform precipitation method is selected from one of the following substances: urea, hexamethyltetramine, urea and oxalic acid (molar ratio is 1:2), and urea and dimethyl oxalate (molar ratio is 1: 2);

the amount of precipitant is calculated as the molar ratio of precipitant to cobalt.

When the precipitator is urea, the molar ratio of the urea to the cobalt is

When the precipitator is hexamethyltetramine, the molar ratio of the hexamethyltetramine to the cobalt is

When the precipitator is urea and oxalic acid, the molar ratio of the urea to the cobalt is

When the precipitator is urea and dimethyl oxalate, the molar ratio of the urea to the cobalt is

Wherein X represents at least 1 element selected from the group consisting of nickel, gold, palladium, platinum, ruthenium, silver, lanthanum and copper;

10. a method for producing a carboxylic acid ester, comprising the steps of: as described above

Any one of the cobalt-based catalysts for producing a carboxylic acid ester is one-step oxidation-esterified with an alcohol in the presence of an oxygen source such as oxygen or an oxygen-containing gas mixture (e.g., air);

the aldehyde is selected from one or a mixture of acrolein and methacrolein;

the alcohol is one or a mixture of two selected from ethylene glycol and methanol.

Evaluation of catalyst: weighing a certain amount of catalyst, adding into a fixed bed reactor, continuously introducing unsaturated aldehyde and alcohol, introducing air (oxygen-containing mixed gas or pure oxygen) at reaction temperature, starting stirring, reacting for a certain time, stopping reaction, and sampling for analysis.

The advantages of the invention are as follows:

according to the present invention, there are provided a novel cobalt-based catalyst, a method for preparing the same, and a method for preparing an unsaturated carboxylic acid ester using the same. The catalyst takes cheap cobalt as a main component of the catalyst instead of noble metals such as Pd, Pt and the like, and has the advantages of low noble metal consumption, high reaction activity, good stability and the like.

Drawings

Fig. 1 is an image of a transmission electron microscope TEM of the catalyst for producing a carboxylic ester in example 3.

Fig. 2 is an image of the catalyst for producing a carboxylic ester in example 3 taken by a scanning electron microscope SEM.

The specific implementation mode is as follows:

the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the present invention.

Examples of preparation of the support

Example 1

10g of 30% silica sol (pH 4.5), 3.0g of aluminum nitrate, 1.96g of magnesium hydroxide, 3g of concentrated nitric acid with the concentration of 65% and 60mL of deionized water are uniformly mixed at 25 ℃, the mixture is kept at 50 ℃ and stirred and aged for 24h to obtain a uniform solid solution suspension, water is removed by rotary evaporation, and the mixture is dried in vacuum at 80 ℃ to obtain a white powdery solid. Placing the solid in a tube furnace, carrying out temperature programmed roasting under nitrogen, starting at 30 ℃, heating to 300 ℃ at the speed of 2.25 ℃/min, keeping the temperature at 300 ℃ for 4h, starting at 300 ℃, heating to 600 ℃ at the speed of 2.5 ℃/min, and keeping the temperature at 600 ℃ for 4 h. And naturally cooling to obtain the SiO2-MgO-Al2O3 metal composite oxide carrier, wherein magnesium oxide, silicon oxide and aluminum oxide in the composite oxide carrier are combined to form a solid solution, so that the acid and alkali resistance of the carrier is improved, and the chemical stability of the carrier is further improved.

Example 2

10g of 30% silica sol (pH 4.5), 1.96g of magnesium hydroxide, 7.5g of zirconium nitrate, 3g of 80% concentrated nitric acid and 60mL of deionized water are uniformly mixed at 25 ℃, the mixture is kept at 50 ℃ and stirred and aged for 24h to obtain a uniform solid solution suspension, water is removed by rotary evaporation, and the mixture is dried in vacuum at 80 ℃ to obtain a white powdery solid. Placing the solid in a tube furnace, carrying out temperature programmed roasting under nitrogen, heating to 30-300 ℃ for 3h (the heating rate is 1.5 ℃/min), keeping at 300 ℃ for 4h, heating to 300-600 ℃ for 3h (the heating rate is 1.7 ℃/min), and keeping at 600 ℃ for 4 h. Naturally cooling to obtain the SiO2-MgO-ZrO2 metal composite oxide carrier.

Example 3

10g of 30% silica sol (pH 4.5), 5g of magnesium nitrate, 6.0g of cerium nitrate, 3g of 60% concentrated nitric acid in mass concentration and 80mL of deionized water are stirred and aged for 24 hours while keeping the mixture at 50 ℃ to obtain a uniform solid solution suspension, and the suspension is subjected to rotary evaporation to remove water and vacuum drying at 80 ℃ to obtain a white powdery solid. Placing the solid in a tube furnace, carrying out temperature programmed roasting under nitrogen, heating to 30-300 ℃ for 3h (the heating rate is 1.5 ℃/min), keeping at 300 ℃ for 4h, heating to 300-600 ℃ for 3h (the heating rate is 1.7 ℃/min), and keeping at 600 ℃ for 4 h. Naturally cooling to obtain the SiO2-MgO-CeO2 metal composite oxide carrier.

Example 4

10g of 30% silica sol (pH 4.5), 3.0g of aluminum nitrate, 1.2g of magnesium hydroxide, 2.0g of zirconium nitrate, 3g of 75% concentrated nitric acid with mass concentration and 90mL of deionized water are mixed uniformly at 25 ℃, the mixture is kept at 50 ℃ and stirred and aged for 24 hours to obtain a uniform solid solution suspension, water is removed by rotary evaporation, and the mixture is dried in vacuum at 80 ℃ to obtain a white powdery solid. Placing the solid in a tube furnace, carrying out temperature programming roasting under nitrogen, heating to 30-300 ℃ for 3h (heating rate of 1.5 ℃/min), keeping at 300 ℃ for 4h, heating to 300-600 ℃ for 3h (heating rate of 1.7 ℃/min), and keeping at 600 ℃ for 4 h. Naturally cooling to obtain the SiO2-MgO-Al2O3-ZrO2 metal composite oxide carrier.

Example 5

10g of 30% silica sol (pH 4.5), 3.0g of aluminum nitrate, 1.2g of magnesium hydroxide, 2.0g of cerium nitrate, 3g of 75% concentrated nitric acid with mass concentration and 90mL of deionized water are mixed uniformly at 25 ℃, the mixture is kept at 50 ℃ and stirred and aged for 24 hours to obtain a uniform solid solution suspension, water is removed by rotary evaporation, and the mixture is dried in vacuum at 80 ℃ to obtain a white powdery solid. Placing the solid in a tube furnace, carrying out temperature programming roasting under nitrogen, heating to 30-300 ℃ for 3h (heating rate of 1.5 ℃/min), keeping at 300 ℃ for 4h, heating to 300-600 ℃ for 3h (heating rate of 1.7 ℃/min), and keeping at 600 ℃ for 4 h. Naturally cooling to obtain the SiO2-MgO-Al2O3-CeO2 metal composite oxide carrier.

Example 6

10g of 30% silica sol (pH 4.5), 3.0g of aluminum nitrate, 1.2g of magnesium hydroxide, 1.0g of zirconium nitrate, 1.0g of cerium nitrate, 3g of concentrated nitric acid with the mass concentration of 75% and 90mL of deionized water are uniformly mixed at 25 ℃, the mixture is kept at 50 ℃ and stirred and aged for 24 hours to obtain a uniform solid solution suspension, water is removed by rotary evaporation, and the mixture is dried in vacuum at 80 ℃ to obtain a white powdery solid. Placing the solid in a tube furnace, carrying out temperature programmed roasting under nitrogen, heating to 30-300 ℃ for 3h (the heating rate is 1.5 ℃/min), keeping at 300 ℃ for 4h, heating to 300-600 ℃ for 3h (the heating rate is 1.7 ℃/min), and keeping at 600 ℃ for 4 h. Naturally cooling to obtain the SiO2-MgO-Al2O3-ZrO2-CeO2 metal composite oxide carrier.

Example 7

Uniformly mixing 3g of 200-mesh 300-mesh column chromatography silica gel, 3.0g of aluminum nitrate, 1.96g of magnesium hydroxide, 3g of concentrated nitric acid with the concentration of 65% and 60mL of deionized water at 25 ℃, keeping the mixture at 50 ℃, stirring and curing for 24h to obtain uniform solid solution suspension, performing rotary evaporation to remove water, and performing vacuum drying at 80 ℃ to obtain white powdery solid. Placing the solid in a tube furnace, carrying out temperature programmed roasting under nitrogen, starting at 30 ℃, heating to 300 ℃ at the speed of 2.25 ℃/min, keeping the temperature at 300 ℃ for 4h, starting at 300 ℃, heating to 600 ℃ at the speed of 2.5 ℃/min, and keeping the temperature at 600 ℃ for 4 h. And naturally cooling to obtain the SiO2-MgO-Al2O3 metal composite oxide carrier, wherein magnesium oxide, silicon oxide and aluminum oxide in the composite oxide carrier are combined to form a solid solution, so that the acid and alkali resistance of the carrier is improved, and the chemical stability of the carrier is further improved.

Catalyst preparation examples

Example 8

Sequentially adding 1g of SiO2-MgO-Al2O3 carrier A, 0.3g of urea, 21.0mg of chloroauric acid, 0.18g of cobalt nitrate and 70mL of deionized water into a reactor, uniformly mixing, stirring at 80 ℃ for reacting for 4 hours, cooling the mixture to room temperature, filtering under reduced pressure to obtain a solid, drying the solid at 80 ℃ in vacuum for 1 hour, and calcining the solid in a muffle furnace at 500 ℃ for 2 hours. And naturally cooling to obtain the catalyst A.

Example 9

1g of SiO2-MgO-ZrO2 carrier B, 0.8g of hexamethyltetramine, 21.0mg of chloroauric acid, 0.18g of cobalt nitrate and 70mL of deionized water are sequentially added into a reactor to be uniformly mixed, the mixture is stirred and reacted for 4 hours at the temperature of 80 ℃, and the mixture is cooled to the room temperature and filtered under reduced pressure. The solid was dried under vacuum at 80 ℃ for 1h and calcined in a muffle furnace at 500 ℃ for 2 h. And naturally cooling to obtain the catalyst B.

Example 10

1g of SiO2-MgO-CeO2 carrier C, 1.0g of hexamethyltetramine, 21.0mg of chloroauric acid, 0.18g of cobalt nitrate and 70mL of deionized water are sequentially added into a reactor to be uniformly mixed, the mixture is stirred and reacted for 4 hours at the temperature of 80 ℃, and the mixture is cooled to the room temperature and filtered under reduced pressure. The solid was dried under vacuum at 80 ℃ for 1h and calcined in a muffle furnace at 500 ℃ for 2 h. And naturally cooling to obtain the catalyst C.

Example 11

1g of SiO2-MgO-Al2O3-ZrO2 carrier D, 1.0g of hexamethyltetramine, 21.0mg of chloroauric acid, 0.18g of cobalt nitrate and 70mL of deionized water are sequentially added into a reactor to be uniformly mixed, the mixture is stirred and reacted for 4 hours at the temperature of 80 ℃, and the mixture is decompressed and filtered after being cooled to the room temperature. The solid was dried under vacuum at 80 ℃ for 1h and calcined in a muffle furnace at 600 ℃ for 2 h. And naturally cooling to obtain the catalyst D.

Example 12

1g of SiO2-MgO-Al2O3-CeO2 carrier E, 0.8g of hexamethyltetramine, 21.0mg of chloroauric acid, 0.18g of cobalt nitrate and 70mL of deionized water are sequentially added into a reactor to be uniformly mixed, the mixture is stirred and reacted for 4 hours at the temperature of 80 ℃, and the mixture is cooled to the room temperature and filtered under reduced pressure. The solid was dried under vacuum at 80 ℃ for 1h and calcined in a muffle furnace at 600 ℃ for 2 h. And naturally cooling to obtain the catalyst E.

Example 13

1g of SiO2-MgO-Al2O3-ZrO2-CeO2 carrier F, 0.8g of hexamethyltetramine, 21.0mg of chloroauric acid, 0.18g of cobalt nitrate and 70mL of deionized water are sequentially added into a reactor to be uniformly mixed, stirred and reacted for 4 hours at the temperature of 80 ℃, and the mixture is cooled to the room temperature and filtered under reduced pressure. The solid was dried under vacuum at 80 ℃ for 1h and calcined in a muffle furnace at 600 ℃ for 2 h. And naturally cooling to obtain the catalyst F.

Example 14

1G of SiO2-MgO-Al2O3 carrier G, 0.3G of urea, 21.0mg of chloroauric acid, 0.18G of cobalt nitrate and 70mL of deionized water are sequentially added into a reactor to be uniformly mixed, the mixture is stirred and reacted for 4 hours at the temperature of 80 ℃, the mixture is cooled to the room temperature, the mixture is decompressed and filtered to obtain a solid, the solid is dried for 1 hour in vacuum at the temperature of 80 ℃, and the solid is placed in a muffle furnace to be calcined for 2 hours at the temperature of 500 ℃. And naturally cooling to obtain the catalyst G.

Experimental results of the catalyst for methyl methacrylate production:

3.0g of catalyst is added into a fixed bed reactor, methacrolein-methanol solution with the mass fraction of 35 percent of methacrolein is continuously added in 12mL/h, air is blown in at the speed of 20mL/h and the pressure is 3Kg/cm3, methyl methacrylate is continuously prepared by reaction at the temperature of 80-85 ℃, the reaction time is 1h and the reaction time is 2000 h, and the experimental results are shown in Table 1.

TABLE 1

Claims

1. A cobalt-based catalyst for producing an unsaturated carboxylic acid ester, wherein cobalt and X in an oxidized state are supported on a carrier in a Co/(Co + X) atomic ratio in the range of 0.05 to 0.99,

wherein X represents at least 1 element selected from the group consisting of nickel, palladium, platinum, ruthenium, silver, lanthanum and copper;

wherein the carrier is a silicon dioxide composition which contains silicon dioxide, magnesium oxide and one, two or three compounds selected from aluminum oxide, zirconium dioxide and cerium dioxide metal compounds; it comprises silicon in the range of 42-90 mole%, magnesium in the range of 4-38 mole%, aluminum in the range of 0-38 mole%, zirconium in the range of 0-35 mole%, cerium in the range of 0-40 mole%, relative to the total molar amount of silicon, magnesium, aluminum, zirconium, and cerium in the carrier.

2. The cobalt-based catalyst for unsaturated carboxylic acid ester production according to claim 1, wherein the active ingredient comprises composite nanoparticles composed of cobalt in an oxidized state and X, the composite nanoparticles being particles composed of X as a core, the surface of the core being coated with cobalt in an oxidized state.

3. The cobalt-based catalyst for unsaturated carboxylic acid ester production according to claim 2, further comprising, in addition to the aforementioned composite nanoparticles supported on the carrier, Co in an oxidized state alone or in addition to the aforementioned composite nanoparticles;

the Co in the active component is a composite oxide containing cobalt, or an oxide of cobalt and a composite oxide containing cobalt.

4. A cobalt-based catalyst for the production of an unsaturated carboxylic acid ester according to any one of claims 1 to 3, characterized in that: the mass content of the active component Co is 0.01-30% of the whole catalyst.

5. The cobalt-based catalyst for unsaturated carboxylic acid ester production according to any one of claims 1 to 3, which has a specific surface area of 20 to 350 m2/g, a maximum frequency of pore diameter of 3 to 80 nm, a pore volume of 0.1 to 1.0 mL/g, and a particle diameter of 10 to 500 um.

6. The cobalt-based catalyst for unsaturated carboxylic acid ester production according to any one of claims 1 to 3, which is in the form of powder, granules, blocks, spheres, columns or other shapes.

7. A method for preparing a cobalt-based catalyst for the production of an unsaturated carboxylic acid ester according to claim 1, comprising the steps of:

a step 1 of preparing an aqueous solution of a soluble metal salt containing cobalt and X, wherein X represents at least 1 element selected from the group consisting of nickel, palladium, platinum, ruthenium, silver, lanthanum and copper, and depositing cobalt and X components on a carrier to obtain a catalyst precursor;

a 2 nd step of subjecting the obtained catalyst precursor to a heat treatment to thereby bring cobalt into an oxidized state; the catalyst precursor is roasted in the atmosphere of hydrogen, oxygen, air, nitrogen or argon; the temperature rising mode can be temperature programming or constant temperature, the temperature is 200 ℃ and 800 ℃, and the roasting time is 2-20 h.

8. The production method of a cobalt-based catalyst for unsaturated carboxylic acid ester according to claim 7, which is a uniform precipitation method;

wherein, the precipitant parent substance used in the uniform precipitation method is selected from one of the following substances: urea, hexamethyltetramine, urea and oxalic acid in a molar ratio of 1:2, and urea and dimethyl oxalate in a molar ratio of 1: 2;

the dosage of the precipitator is calculated by the molar ratio of the precipitator to the cobalt;

when the precipitator is urea, the molar ratio of urea to cobalt is 1.5: 1-40: 1

When the precipitator is hexamethyltetramine, the molar ratio of the hexamethyltetramine to the cobalt is 0.75: 1-20: 1

When the precipitator is urea and oxalic acid, the molar ratio of urea to cobalt is 0.75: 1-20: 1

When the precipitator is urea and dimethyl oxalate, the molar ratio of the urea to the cobalt is 0.75: 1-20: 1

Here, X represents at least 1 element selected from the group consisting of nickel, palladium, platinum, ruthenium, silver, lanthanum, and copper.

9. A method for producing a carboxylic acid ester, comprising the steps of: in the presence of oxygen or oxygen-containing mixed gas oxygen source, carrying out one-step oxidation esterification on unsaturated aldehyde and alcohol by using the cobalt-based catalyst for producing unsaturated carboxylic ester according to any one of claims 1 to 6;

the aldehyde is selected from one or a mixture of acrolein and methacrolein;