CN117680162A - Cobalt-molybdenum catalyst and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of catalysts, and discloses a cobalt-molybdenum catalyst, a preparation method and application thereof. The cobalt molybdenum catalyst comprises a cobalt molybdenum component comprising: co (Co) ⁰ Co-O-Mo and MoO _x The method comprises the steps of carrying out a first treatment on the surface of the Wherein Co is ⁰ Is positioned in the depth range of 3-10nm of the surface of the cobalt-molybdenum catalyst; co based on the total molar amount of the cobalt-molybdenum component in the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst ⁰ The molar content of (2) is 25-55%. The catalyst prepared by the invention is more suitable for realizing hydrodeoxygenation reaction of sorbitol at the terminal position due to the acid strength and the concentration of hydrogenation active sites, thereby inhibiting the generation of C ₃ The proportion of the product promotes C ₂ Generating a product; in addition, the excellent hydrodeoxygenation activity of the catalyst promotes C ₂ Intermediate productsTo ethanol. The conversion rate of the sorbitol in the catalyst reaches 100% in a continuous fixed bed reactor, and the ethanol selectivity reaches more than or equal to 70%. Meanwhile, the catalyst has long service life and good stability.

Description

Cobalt-molybdenum catalyst and its preparation method and application

Technical Field

The present invention relates to the technical field of catalysts, and in particular to a cobalt-molybdenum catalyst and a preparation method and application thereof.

Background Art

With the consumption of fossil energy worldwide, energy and environmental issues are becoming increasingly prominent. Ethanol gasoline can effectively replace part of the oil and increase the proportion of clean energy in fuel consumption. At the same time, the addition of ethanol can reduce the addition of high-octane components such as aromatics in oil products, thereby reducing the emission of secondary PM 2.5 caused by the use of aromatics. Studies have shown that adding 10% volume fraction of ethanol to ethanol gasoline can reduce primary PM 2.5 in automobile exhaust, with a 36% reduction for general emission vehicles and a 64.6% reduction for high emission vehicles.

There are currently three main ethanol production processes: 1) petroleum-based ethylene hydration; 2) coal-based syngas; 3) biomass fermentation. Petroleum-based and coal-based ethanol conversion does not achieve green production. As a "zero-carbon renewable energy", biomass, if effectively utilized, can reduce the consumption of fossil energy, and at the same time directly solve the problem of air pollution caused by the arbitrary burning of agricultural and forestry wastes such as straw. However, the current conversion reaction efficiency of biomass using fermentation is low. As one of the twelve most promising platform biomass compounds, sorbitol has great application prospects in converting sorbitol into more valuable chemicals.

"Cu/C-catalyzed Hydrogenolysis of Sorbitol to glycols-On the Influence of Particle Size and Base" (Wang X, Beine AK, Hausoul P, et al. ChemCatChem [J], 2019, 11 (16): 4123.) discloses the use of Cu-based Cu/C catalysts of different particle sizes to promote the conversion of sorbitol to glycerol in a kettle reactor under the condition of Ca(OH) ₂ as an alkaline additive. Although this experiment has made progress in the application of biomass, the addition of alkaline additives will increase the cost during the separation of liquid products and will damage the reactor. "Sorbitol Hydrogenolysis over Hybrid Cu/CaO-Al ₂ O ₃ Catalysts: Tunable Activity and Selectivity with Solid Base Incorporation" (Jin X, Shen J, Yan W, et al. ACS Catalysis [J], 2015.) used Cu/CaO-Al ₂ O ₃ catalysts to carry out sorbitol hydrogenolysis reaction, and obtained more than 72% C ₂ -C ₃ polyol selectivity under the reaction conditions without adding alkaline additives. At the same time, "Role of metals Cu, Ni and Co on the acidic and redox properties of Mo catalysts supported on Al ₂ O ₃ spheres for glycerol conversion" (Santos R, Braga D, Pinheiro AN, et al. Catalysis Science & Technology [J], 2016, 6 (13).) achieved the hydrogenolysis of glycerol using Mo-based catalysts. However, most of these reactions are currently carried out in autoclave reactors, and the product separation process is more complicated than that of fixed-bed reactors.

Summary of the invention

The purpose of the present invention is to overcome the problems of low conversion rate and low stability of the catalyst in the prior art, and to provide a cobalt-molybdenum catalyst and its preparation method and application. The cobalt-molybdenum catalyst of the present invention can be applied to a continuous fixed bed reactor, and in the chemical process of converting sorbitol to ethanol through hydrogenolysis reaction, no homogeneous auxiliary agent needs to be added to the reaction system.

In order to achieve the above object, the first aspect of the present invention provides a cobalt-molybdenum catalyst, comprising a cobalt-molybdenum component, wherein the cobalt-molybdenum component comprises: Co ⁰ , Co-O-Mo and MoO _x ; wherein Co ⁰ is located within a depth range of 3-10 nm from the surface of the cobalt-molybdenum catalyst; based on the total molar amount of the cobalt-molybdenum component within a depth range of 3-10 nm from the surface of the cobalt-molybdenum catalyst, the molar content of Co ⁰ is 25-55%.

A second aspect of the present invention provides a method for preparing a catalyst, the preparation method comprising:

S1, mixing a soluble cobalt salt solution and a molybdate solution to form a mixed solution; adding anhydrous ethanol to react to obtain a precipitate;

S2, sequentially separating, first drying and first calcining the precipitate to obtain a catalyst intermediate;

S3. Loading the noble metal auxiliary salt solution onto the catalyst intermediate by an excess impregnation method, allowing the catalyst intermediate to stand in a negative pressure environment, and sequentially performing a second drying and a second calcination to obtain a cobalt-molybdenum catalyst precursor, and then performing post-treatment to obtain a cobalt-molybdenum catalyst.

The third aspect of the present invention provides a cobalt-molybdenum catalyst prepared by the aforementioned preparation method.

A fourth aspect of the present invention provides the use of the aforementioned cobalt-molybdenum catalyst in the hydrogenolysis of sorbitol to produce ethanol.

A fifth aspect of the present invention provides a method for preparing ethanol by hydrogenolysis of sorbitol, the method comprising: subjecting a sorbitol aqueous solution and hydrogen to a hydrogenolysis reaction in the presence of the aforementioned cobalt-molybdenum catalyst.

Through the above technical solution, the present invention has the following significant technical effects:

1) The cobalt-molybdenum catalyst of the present invention comprises a cobalt-molybdenum component, wherein the cobalt-molybdenum component comprises: Co ⁰ , Co-O-Mo and MoO _x ; wherein Co ⁰ is located within a depth range of 3-10 nm on the surface of the cobalt-molybdenum catalyst; based on the total molar amount of the cobalt-molybdenum component within a depth range of 3-10 nm on the surface of the cobalt-molybdenum catalyst, the molar content of Co ⁰ is 25-55%. The cobalt-molybdenum catalyst of the present invention has the characteristics of high conversion rate, good stability and long life, can be applied to a continuous fixed bed reactor, and in the chemical process of completing the conversion of sorbitol to ethanol through hydrogenolysis reaction, no homogeneous additive needs to be added to the reaction system.

2) The cobalt-molybdenum catalyst of the present invention is a low specific surface area non-microporous catalyst, which ensures that the reactants and intermediates can react on the catalyst surface, ensures that the reactants and intermediates can react in series faster on the catalyst surface, and ensures that the stability of the Co-O-Mo active site can be ensured in the limited hydrogen overflow effect of H activated by ^Co0 , while avoiding the blockage of the catalyst pores caused by the side reactions of the reaction intermediates generated in the reaction process in the pores. Therefore, the catalyst has a stable and efficient activity of selectively hydrogenolyzing sorbitol to produce ethanol.

3) The catalyst prepared by the present invention is more suitable for realizing the hydrodeoxygenation reaction of sorbitol at the terminal position due to the acid strength and the concentration of hydrogenation active sites, thereby inhibiting the hydrodeoxygenation reaction at the _C2 position and thus inhibiting the proportion of the generated _C3 product, and promoting the generation of the _C2 product; in addition, the excellent hydrodeoxygenation activity of the catalyst promotes the conversion of the _C2 intermediate product into ethanol.

4) The catalyst has a sorbitol conversion rate of 100% and an ethanol selectivity of ≥70% in a continuous fixed bed reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a SEM image of the CoMoO ₄ catalyst intermediate prepared in Example 4 of the present invention;

FIG2 is a SEM image of the 0.2Pt/CoMoO ₄ catalyst prepared in Example 4 of the present invention;

FIG. 3 is a Raman spectrum of the CoMoO ₄ catalyst intermediate prepared in Example 4 of the present invention and the 0.2Pt/CoMoO ₄ catalyst prepared after loading after reduction.

DETAILED DESCRIPTION

The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.

A first aspect of the present invention provides a cobalt-molybdenum catalyst, comprising a cobalt-molybdenum component, wherein the cobalt-molybdenum component comprises: Co ⁰ , Co-O-Mo and MoO _x ; wherein Co ⁰ is located within a depth range of 3-10 nm from the surface of the cobalt-molybdenum catalyst; based on the total molar amount of the cobalt-molybdenum component within a depth range of 3-10 nm from the surface of the cobalt-molybdenum catalyst, the molar content of Co ⁰ is 25-55%, for example, 30%, 35%, 40%, 45% and any value in a range consisting of any two values.

In the present invention, Co ⁰ represents zero-valent cobalt.

In the present invention, the depth range of 3-10 nm from the surface refers to extending 3-10 nm from the surface of the catalyst and perpendicular to the catalyst surface to the inside of the catalyst, and each component and content is measured within the range of 3-10 nm from the surface to the inside.

In the cobalt-molybdenum catalyst prepared by the method of the present invention, the ^Co0 component can be used as a hydrogenation/dehydrogenation active site in the catalyst, and the Co-O-Mo species and _MoOx species formed after Co and Mo establish a strong interaction can provide acidic active sites, which can provide multifunctional and efficient conversion active sites for hydrogenolysis of sorbitol to ethanol.

In some embodiments, in the cobalt-molybdenum component, the molar ratio of cobalt to molybdenum is 1:2 to 2:1.

In some embodiments, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10 nm from the surface of the cobalt-molybdenum catalyst, the molar content of Co-O-Mo within the depth range of 3-10 nm from the surface of the cobalt-molybdenum catalyst is 25-30%, for example, 26%, 27%, 28%, 29% and any value in the range of any two values.

In some embodiments, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10 nm from the surface of the cobalt-molybdenum catalyst, the molar content of MoO _x within the depth range of 3-10 nm from the surface of the cobalt-molybdenum catalyst is 45-55%, for example, 46%, 47%, 48%, 49%, 50%, 52%, 54% and any value in the range consisting of any two values.

In some embodiments, the noble metal component is selected from at least one of Pt, Ru, and Pd.

In some embodiments, based on the total weight of the cobalt-molybdenum catalyst, the loading amount of the noble metal component is 0.05-0.5 wt %, for example, 0.08%, 0.1%, 0.2%, 0.4% and any value in the range of any two values.

The present invention uses a relatively low amount of noble metal added as an auxiliary agent to prepare a catalyst, and ensures that Co ⁰ species are generated on the catalyst surface to promote the activity of the hydrogenation reaction through the prominent hydrogen overflow effect of the noble metal; and the noble metal auxiliary agent and the Co ⁰ species generated in situ after pretreatment have excellent hydrogen activation capabilities, which ensures the stability of the chemical environment on the catalyst surface and prolongs the life of the catalyst.

In some embodiments, the cobalt-molybdenum catalyst is a non-microporous catalyst.

In some embodiments, the cobalt-molybdenum catalyst has a specific surface area of 10-20 m ² /g.

In some embodiments, the bulk density of the cobalt-molybdenum catalyst is 0.8-1.5 g/cm ³ .

In some embodiments, the average particle size of the cobalt-molybdenum catalyst is 20-80 mesh.

The cobalt-molybdenum catalyst of the present invention is a low specific surface area non-microporous catalyst, which ensures that both the reactant and the intermediate can react on the catalyst surface, ensures that the reactant and the intermediate can react in series faster on the catalyst surface, and ensures that the stability of the Co-O-Mo active site can be ensured in the limited hydrogen overflow effect of H activated by ^Co0 , while avoiding the blockage of the catalyst pores caused by the reaction intermediates generated during the reaction in the pores. Therefore, the catalyst has stable and efficient selective hydrogenolysis of sorbitol to generate ethanol.

A second aspect of the present invention provides a method for preparing a catalyst, the preparation method comprising:

S1, mixing a soluble cobalt salt solution and a molybdate solution to form a mixed solution; adding anhydrous ethanol to react to obtain a precipitate;

S2, sequentially separating, first drying and first calcining the precipitate to obtain a catalyst intermediate;

S3. Loading the noble metal auxiliary salt solution onto the catalyst intermediate by an excess impregnation method, allowing the catalyst intermediate to stand in a negative pressure environment, and sequentially performing a second drying and a second calcination to obtain a cobalt-molybdenum catalyst precursor, and performing post-treatment to obtain a cobalt-molybdenum catalyst.

In step S1, the specific steps of mixing the soluble cobalt salt solution and the molybdate solution include: weighing a soluble salt compound containing cobalt as a Co source and a soluble molybdate as a Mo source, dissolving them in deionized water respectively, and dissolving the two solutions uniformly by stirring to obtain a Co solution and a molybdate solution respectively, and adding the cobalt solution drop by drop into the molybdate solution, and continuously stirring to form a mixed solution.

In some embodiments, in the mixed solution, the molar ratio of cobalt to molybdenum is 1:2-2:1.

In some embodiments, the volume ratio of the anhydrous ethanol to the mixed solution is 1:1-1:2.

In some embodiments, the soluble cobalt salt is selected from at least one of cobalt nitrate, cobalt acetate, cobalt chloride and cobalt sulfate; preferably, the concentration of the soluble cobalt salt is 4-8 mmol/L.

In some embodiments, the soluble molybdate is selected from at least one of ammonium molybdate, sodium molybdate and potassium molybdate; preferably, the concentration of the soluble molybdate is 7.8-12 mmol/L.

In step S1, the reaction is carried out in a water bath at a temperature of 80-90° C. for 3-5 hours. Specifically, the mixed solution is heated in a water bath, and anhydrous ethanol is added dropwise, and the temperature is maintained at 80-90° C., and stirring is continued for 3-5 hours to produce a precipitate.

Step S2 specifically includes: separating the precipitate obtained in step S1, and washing it with deionized water and ethanol, placing the washed precipitate in a drying oven for a first drying to obtain a solid sample; and then placing the obtained solid sample in a muffle furnace for a first roasting to obtain a catalyst intermediate.

In some embodiments, the first drying is carried out at a temperature of 100-120° C. and for a time of 12-24 hours.

In some embodiments, the first calcination is performed at a temperature of 400-550° C. and for a time of 2-6 hours.

Step S3 specifically includes: dissolving the precious metal additive salt in deionized water, stirring to make it uniform, and obtaining a precious metal additive salt solution; and loading the precious metal additive salt onto the catalyst intermediate prepared in step S2 by an excess impregnation method, standing in a negative pressure environment for 5-10 minutes to ensure that the precious metal additive can be evenly loaded on the surface of the catalyst precursor, and then placing it in a drying oven for a second drying to obtain a solid sample; and then placing the dried solid sample in a muffle furnace for a second calcination to obtain a cobalt-molybdenum catalyst.

In some embodiments, the noble metal auxiliary salt is selected from at least one of ruthenium nitrate, ruthenium chloride, rhodium nitrate, palladium nitrate, diamine dinitrite platinum, chloroplatinic acid and chloroauric acid; preferably, the loading amount of the noble metal is 0.05-0.5wt%.

In some embodiments, the second drying is performed at a temperature of 100-120° C. for a time of 12-24 hours.

In some embodiments, the second calcination is carried out at a temperature of 400-550° C. and for a time of 2-6 hours.

In step S3, the post-treatment includes: granulating the cobalt-molybdenum catalyst precursor and then reducing it.

The present invention has no specific limitation on the granulation step, and the commonly used granulation step for catalysts can be used. In some embodiments, the granulation step may include: grinding the cobalt-molybdenum catalyst precursor, maintaining it at 10-15 MPa for 8-16 minutes for tableting, and then granulating the catalyst.

In some embodiments, the particle size of the granulation is in the range of 20-80 mesh.

In some embodiments, the reduction temperature is 200-400°C, the time is 6-12h, the _H2 space velocity is 3000-4800mL/(g·h); the _H2 content for reduction is 100%-5% (volume content); and the system pressure during the reduction process is 0.1-3MPa.

In the present invention, the reduction step can be carried out during the preparation of the catalyst or before use, and the reduction step can be reasonably selected according to actual needs.

In the present invention, the addition of the noble metal promoter promotes the generation of some Co ⁰ species on the catalyst surface, while reducing the noble metal loading, creating more hydrogenation active sites for the catalyst surface to promote the selective hydrogenation reaction in the sorbitol conversion reaction; and due to the addition of a small amount of noble metal, the acidity of the catalyst surface can be adjusted, and in the reduction step, due to the loading of a small amount of noble metal, more Co ⁰ , Co-O-Mo and MoO _x are formed on the catalyst surface, so that the catalyst surface has the presence of Co ⁰ species, thereby ensuring stable and efficient hydrogen activation ability, thereby ensuring the stability of the Co-O-Mo active sites.

The third aspect of the present invention provides a cobalt-molybdenum catalyst prepared by any of the preparation methods described above.

The fourth aspect of the present invention provides the use of the cobalt-molybdenum catalyst described in any one of the first and third aspects in the hydrogenolysis of sorbitol to produce ethanol.

The cobalt-molybdenum catalyst prepared by the present invention, which uses a small amount of precious metal as an auxiliary agent, is more suitable for realizing the hydrodeoxygenation reaction of sorbitol at the terminal position due to the presence of a small amount of precious metal, which regulates the acid strength of the active sites generated on the surface of the catalyst during the reduction process and the concentration of the hydrogenation active sites, thereby inhibiting the hydrodeoxygenation reaction at the _C2 position and inhibiting the proportion of the generated _C3 product, and promoting the generation of the _C2 product; at the same time, since the catalyst exists in a non-porous structure, the deactivation of sorbitol molecules in the catalyst pores due to poor diffusion effect is avoided; in addition, the excellent hydrodeoxygenation activity of the catalyst promotes the conversion of the _C2 intermediate product into ethanol. In addition, the catalyst has a sorbitol conversion rate of 100% and an ethanol selectivity of ≥70% in a continuous fixed bed reactor.

A fifth aspect of the present invention provides a method for preparing ethanol by hydrogenolysis of sorbitol, the method comprising: subjecting a sorbitol aqueous solution and hydrogen to a hydrogenolysis reaction in the presence of the cobalt-molybdenum catalyst described in any one of the preceding items or the cobalt-molybdenum catalyst obtained by the preparation method described in any one of the preceding items.

In some embodiments, the concentration of the sorbitol aqueous solution is 20-60 g/L.

In some embodiments, the liquid space velocity of the sorbitol solution is 2.4-12 mL/(g·h), and the gas space velocity of hydrogen is 1800-5400 mL/(g·h).

In some embodiments, the temperature of the hydrogenolysis reaction is 200-285° C. and the pressure is 3-5 MPa.

The catalyst provided by the present invention can promote the dehydrogenation of sorbitol to produce an intermediate product with retro-aldol condensation activity, and the intermediate product breaks the C-C bond through retro-aldol condensation reaction to generate a low-carbon intermediate, and the low-carbon intermediate is converted into multiple active sites of ethanol through a hydrodeoxygenation reaction; in addition, the catalyst has a large number of active sites for adsorbing sorbitol to achieve efficient conversion of sorbitol; in addition, the catalyst also has high stability, and can achieve continuous and efficient conversion of sorbitol into ethanol in a long reaction time, so as to achieve efficient and green application of biomass.

The present invention is described in detail below by way of examples, but the protection scope of the present invention is not limited to the following description. If no specific conditions are specified in the examples, conventional conditions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained through commercial channels.

Example 1

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 0.4mmol Co(NO ₃ ) ₂ as a cobalt source and 0.6mmol (NH ₄ ) ₂ MoO ₄ as a molybdenum source, dissolve them in 50mL deionized water respectively, and stir to fully dissolve the two solutions;

2) Add the Co(NO ₃ ) ₂ solution dropwise into the (NH ₄ ) ₂ MoO ₄ solution while stirring continuously;

3) The mixed solution prepared in step 2) was transferred to a three-necked flask and continuously stirred under water bath heating at a stirring rate of 300 rpm. When the temperature rose to 60° C., 100 mL of anhydrous ethanol was added dropwise to the three-necked flask at a dropping rate of 0.8 mL/min.

4) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 85° C. and stirred for 4 h;

5) separating the precipitate obtained in step 4) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

6) placing the precipitate obtained in step 5) in a drying oven and drying at 120° C. for 12 h;

7) placing the solid sample dried in step 6) in a muffle furnace and calcining it at 500° C. for 3 h to obtain a catalyst intermediate;

8) dissolving Pd(NO ₃ ) ₂ in a small amount of deionized water, stirring to make it uniform, and loading the solution onto the catalyst intermediate prepared in step 7) by an excess impregnation method, and then standing the loaded catalyst intermediate in a negative pressure environment for 5 minutes to ensure that the noble metal is uniformly loaded on the catalyst surface, and controlling the Pd content to account for 0.1wt% of the total weight of the cobalt-molybdenum catalyst; then placing it in a drying oven and drying it at 120°C for 12 hours;

9) placing the dried sample obtained in step 8) in a muffle furnace and calcining it at 400° C., maintaining the calcination temperature for 2 hours, to obtain a 0.1Pd/CoMoO ₄ catalyst precursor;

10) granulating the catalyst precursor prepared in step 9) to a particle size of 40-60 mesh;

11) 1 g of the catalyst precursor of step 9) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction begins, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 300°C, the heating rate is 2°C/min, the reduction time is 10h, and the _H2 gas rate during the reduction process is 4800mL/(g·h); the _H2 content of the reducing gas is 100% (volume content); the system pressure during the reduction process is 0.1MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 5.0MPa, the reaction temperature is 245°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 5400mL/(g·h), the liquid feed flow rate is 2.4mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 80g/L.

It was detected that in the 0.1Pd/CoMoO4 _catalyst after reduction, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst, the molar content of ^Co0 was 20%, the molar content of Co-O-Mo was 45%, and the molar content of _MoOx was 34%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using the catalyst is shown in Table 1.

In the following table, LA: lactic acid; EG: ethylene glycol; 1,2-PG: 1,2-propylene glycol; 1,3-PG: 1,3-propylene glycol; 1,3-BG: 1,3-butylene glycol; 1,2-BG: 1,2-butylene glycol; EtOH: ethanol.

Table 1 Product distribution of hydrogenolysis of sorbitol over 0.1Pd/CoMoO ₄ catalyst

Example 2

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 0.4mmol (CH ₃ COO) ₂ Co as a cobalt source and 0.6mmol Na ₂ MoO ₄ as a molybdenum source, dissolve them in 50mL deionized water respectively, and stir to fully dissolve the two solutions;

2) Add the (CH ₃ COO) ₂ Co solution dropwise into the Na ₂ MoO ₄ solution while stirring continuously;

3) The mixed solution prepared in step 2) was transferred to a three-necked flask and continuously stirred under water bath heating at a stirring rate of 300 rpm. When the temperature rose to 60° C., 100 mL of anhydrous ethanol was added dropwise to the three-necked flask at a dropping rate of 0.8 mL/min.

4) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 85° C. and stirred for 4 h;

5) separating the precipitate obtained in step 4) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

6) placing the precipitate obtained in step 5) in a drying oven and drying at 120° C. for 12 h;

7) placing the solid sample dried in step 6) in a muffle furnace and calcining it at 500° C. for 3 h to obtain a catalyst intermediate;

8) dissolving HN ₄ O ₁₀ Ru in a small amount of deionized water, stirring to make it uniform, and loading the solution onto the catalyst intermediate prepared in step 7) by an excess impregnation method, and then standing the loaded catalyst intermediate in a negative pressure environment for 5 minutes to ensure that the noble metal is uniformly loaded on the catalyst surface, and controlling the Ru content to account for 0.2wt% of the total weight of the cobalt-molybdenum catalyst; then placing it in a drying oven and drying it at 120°C for 12 hours;

9) placing the dried sample obtained in step 8) in a muffle furnace and calcining it at 400° C., maintaining the calcination temperature for 2 hours, to obtain a 0.2Ru/CoMoO ₄ catalyst precursor;

10) granulating the catalyst precursor prepared in step 9) to a particle size of 40-60 mesh;

11) 1 g of the catalyst precursor of step 9) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction begins, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 300°C, the heating rate is 2°C/min, the reduction time is 10h, and the _H2 gas rate during the reduction process is 3000mL/(g·h); the _H2 content of the reducing gas is 20% (volume content); the system pressure during the reduction process is 3MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 5.0MPa, the reaction temperature is 245°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 1800mL/(g·h), the liquid feed flow rate is 6mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 80g/L.

It was detected that in the 0.2Ru/ _CoMoO4 catalyst after reduction, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst, the molar content of ^Co0 was 14%, the molar content of Co-O-Mo was 56%, and the molar content of _MoOx was 28%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using the catalyst is shown in Table 2.

Table 2 Product distribution of hydrogenolysis of sorbitol over 0.2Ru/ _CoMoO4 catalyst

Example 3

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 0.8 mmol (CH ₃ COO) ₂ Co as a cobalt source and 1.0 mmol K ₂ MoO ₄ as a molybdenum source, dissolve them in 100 mL of deionized water, and stir to fully dissolve the two solutions;

2) Add the (CH ₃ COO) ₂ Co solution dropwise into the K ₂ MoO ₄ solution while stirring continuously;

3) The mixed solution prepared in step 2) was transferred to a three-necked flask and continuously stirred under water bath heating at a stirring rate of 150 rpm. When the temperature rose to 60° C., 100 mL of anhydrous ethanol was added dropwise to the three-necked flask at a dropping rate of 0.6 mL/min.

4) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 75° C. and stirred for 4 h;

5) separating the precipitate obtained in step 4) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

6) placing the precipitate obtained in step 5) in a drying oven and drying at 120° C. for 12 h;

7) placing the solid sample dried in step 6) in a muffle furnace and calcining it at 500° C. for 3 h to obtain a catalyst intermediate;

8) dissolving chloroplatinic acid in a small amount of ethylene glycol, stirring to make it uniform, and loading the solution onto the catalyst intermediate prepared in step 7) by an excess impregnation method, and then standing the loaded catalyst intermediate in a negative pressure environment for 15 minutes to ensure that the noble metal is uniformly loaded on the catalyst surface, and controlling the Pt content to account for 0.05wt% of the total weight of the cobalt-molybdenum catalyst; then placing it in a drying oven and drying it at 120°C for 12 hours;

9) placing the dried sample obtained in step 8) in a muffle furnace for calcination at 400° C., maintaining the calcination temperature for 2 h, to obtain a 0.05Pt/CoMoO ₄ catalyst precursor;

10) granulating the catalyst precursor prepared in step 9) to a particle size of 20-40 mesh;

11) 0.5 g of the catalyst precursor of step 9) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction starts, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 380°C, the heating rate is 2°C/min, the reduction time is 10h, and the _H2 gas rate during the reduction process is 4200mL/(g·h); the _H2 content of the reducing gas is 5% (volume content); the system pressure during the reduction process is 2MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 5.0MPa, the reaction temperature is 245°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 4200mL/(g·h), the liquid feed flow rate is 9mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 80g/L.

It was detected that in the reduced Pt/ _CoMoO4 catalyst, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10 nm on the surface of the cobalt-molybdenum catalyst, the molar content of ^Co0 was 9%, the molar content of Co-O-Mo was 63%, and the molar content of _MoOx was 26%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using the catalyst is shown in Table 3.

Table 3 Product distribution of hydrogenolysis of sorbitol over 0.05Pt/CoMoO ₄ catalyst

Example 4

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 0.8 mmol CoCl ₂ as a cobalt source and 1.0 mmol Na ₂ MoO ₄ as a molybdenum source, dissolve them together in 100 mL of deionized water, and stir to fully dissolve the two solutions;

2) Add the CoCl ₂ solution dropwise into the Na ₂ MoO ₄ solution while stirring continuously;

3) The mixed solution prepared in step 2) was transferred to a three-necked flask and continuously stirred under water bath heating at a stirring rate of 240 rpm. When the temperature rose to 60° C., 100 mL of anhydrous ethanol was added dropwise to the three-necked flask at a dropping rate of 1.0 mL/min.

4) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 85° C. and stirred for 4 h;

5) separating the precipitate obtained in step 4) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

6) placing the precipitate obtained in step 5) in a drying oven and drying at 120° C. for 12 h;

7) placing the solid sample dried in step 6) in a muffle furnace and calcining it at 500° C. for 3 h at a heating rate of 2° C./min to obtain a CoMoO ₄ catalyst intermediate;

8) dissolving chloroplatinic acid in a small amount of ethylene glycol, stirring to make it uniform, and loading the solution onto the catalyst intermediate prepared in step 7) by an excess impregnation method, and then standing the loaded catalyst intermediate in a negative pressure environment for 15 minutes to ensure that the noble metal is uniformly loaded on the catalyst surface, and controlling the Pt content to account for 0.2wt% of the total weight of the cobalt-molybdenum catalyst; then placing it in a drying oven and drying it at 120°C for 12 hours;

9) placing the dried sample obtained in step 8) in a muffle furnace and calcining it at 400° C., maintaining the calcination temperature for 2 hours, to obtain a 0.2Pt/CoMoO ₄ catalyst precursor;

10) granulating the catalyst precursor prepared in step 9) to a particle size of 20-40 mesh;

11) 0.5 g of the catalyst precursor of step 9) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction starts, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 380°C, the heating rate is 2°C/min, the reduction time is 10h, and the _H2 gas rate during the reduction process is 4200mL/(g·h); the _H2 content of the reducing gas is 100% (volume content); the system pressure during the reduction process is 0.1MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 3.0MPa, the reaction temperature is 245°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 4200mL/(g·h), the liquid feed flow rate is 12mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 25g/L.

It was detected that in the 0.2Pt/ _CoMoO4 catalyst after reduction, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst, the molar content of ^Co0 was 10%, the molar content of Co-O-Mo was 69%, and the molar content of _MoOx was 20%.

As shown in Figure 1, it is a SEM image of the CoMoO ₄ catalyst intermediate prepared in this example. As shown in Figure 2, it is a SEM image of the 0.2Pt/CoMoO ₄ catalyst prepared in this example; from the comparison between Figure 1 and Figure 2, it can be seen that the 0.2Pt/CoMoO ₄ after loading still has a rod-like morphology, indicating that the loading process will not damage the catalyst precursor structure.

As shown in FIG3 , the Raman spectra of the CoMoO ₄ catalyst intermediate prepared in this embodiment and the 0.2Pt/CoMoO ₄ catalyst prepared after loading are reduced. As can be seen from FIG3 , since the loading amount of the noble metal in the prepared catalyst is low, the peaks attributable to the noble metal structure cannot be observed in the Raman spectrum. The peaks at 671 cm ^-1 , 808 cm ^-1 , and 938 cm ^-1 can be respectively attributed to the bending vibration of the Mo=O bond, the symmetric stretching vibration of Mo-O-Mo, and the asymmetric stretching vibration of Mo-O-Mo. The peak at 349 cm ^-1 can be considered as proof of the existence of Co-O-Mo. The above can illustrate that the catalyst prepared in this embodiment has MoO _x and Co-O-Mo active sites.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using the catalyst is shown in Table 4.

Table ₄ Product distribution of hydrogenolysis of sorbitol over 0.2Pt/CoMoO4 catalyst

Example 5

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 0.5mmol Co(NO ₃ ) ₂ as a cobalt source and 0.8mmol K ₂ MoO ₄ as a molybdenum source, dissolve them together in 100mL deionized water, and stir to fully dissolve the two solutions;

2) transferring the mixed solution prepared in step 1) into a three-necked flask and continuously stirring it in a water bath at a stirring rate of 250 rpm. When the temperature rises to 60° C., 100 mL of anhydrous ethanol is added dropwise into the three-necked flask at a dropping rate of 0.8 mL/min.

3) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 80° C. and stirred for 4 h;

4) separating the precipitate obtained in step 3) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

5) placing the precipitate obtained in step 4) in a drying oven and drying at 150° C. for 10 h;

6) placing the solid sample dried in step 5) in a muffle furnace and calcining it at 500° C. for 3 h at a heating rate of 2° C./min to obtain a catalyst intermediate;

7) dissolving platinum diamine dinitrite in a small amount of ethylene glycol, stirring to make it uniform, and loading the solution onto the catalyst intermediate prepared in step 6) by an excess impregnation method, and then standing the loaded catalyst intermediate in a negative pressure environment for 20 minutes to ensure that the noble metal is uniformly loaded on the catalyst surface, and controlling the Pt content to account for 0.1wt% of the total weight of the cobalt-molybdenum catalyst; then placing it in a drying oven and drying it at 120°C for 12 hours;

8) placing the dried sample obtained in step 7) in a muffle furnace and calcining it at 400° C., maintaining the calcination temperature for 2 hours, to obtain a 0.1Pt/CoMoO ₄ catalyst precursor;

9) granulating the catalyst precursor prepared in step 8) to a particle size of 20-40 mesh;

10) 0.5 g of the catalyst precursor of step 9) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction starts, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 350°C, the heating rate is 2°C/min, the reduction time is 10h, and the _H2 gas rate during the reduction process is 4800mL/(g·h); the _H2 content of the reducing gas is 100% (volume content); the system pressure during the reduction process is 0.1MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 4.0MPa, the reaction temperature is 250°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 4200mL/(g·h), the liquid feed flow rate is 6mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 50g/L.

It was detected that in the 0.1Pt/CoMoO4 _catalyst after reduction, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst, the molar content of ^Co0 was 10%, the molar content of Co-O-Mo was 49%, and the molar content of _MoOx was 40%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using this catalyst is shown in Table 5.

Table 5 Product distribution of hydrogenolysis of sorbitol over 0.1Pt/CoMoO ₄ catalyst

Example 6

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 0.6mmol CoCl ₂ as a cobalt source and 1.0mmol K ₂ MoO ₄ as a molybdenum source, dissolve them together in 100mL deionized water, and stir to fully dissolve the two solutions;

2) The mixed solution prepared in step 1) was transferred to a three-necked flask and continuously stirred under water bath heating at a stirring rate of 260 rpm. When the temperature rose to 60° C., 100 mL of anhydrous ethanol was added dropwise to the three-necked flask at a dropping rate of 0.5 mL/min.

3) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 80° C. and stirred for 4 h;

4) separating the precipitate obtained in step 3) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

5) placing the precipitate obtained in step 4) in a drying oven and drying at 120° C. for 10 h;

6) placing the solid sample dried in step 5) in a muffle furnace and calcining it at 450° C. for 4 h at a heating rate of 2° C./min to obtain a catalyst intermediate;

7) dissolving platinum diamine dinitrite in a small amount of ethylene glycol, stirring to make it uniform, and loading the solution onto the catalyst intermediate prepared in step 6) by an excessive impregnation method, and then standing the loaded catalyst intermediate in a negative pressure environment for 30 minutes to ensure that the noble metal is uniformly loaded on the catalyst surface, and controlling the content of Rt to account for 0.1wt% of the total weight of the cobalt-molybdenum catalyst; then placing it in a drying oven and drying it at 120°C for 12 hours;

8) placing the dried sample obtained in step 7) in a muffle furnace and calcining it at 450° C., maintaining the calcination temperature for 2 hours, to obtain a 0.1Pt/CoMoO ₄ catalyst precursor;

9) granulating the catalyst precursor prepared in step 8) to a particle size of 20-40 mesh;

10) 0.5 g of the catalyst precursor of step 9) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction starts, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 360°C, the heating rate is 2°C/min, the reduction time is 10h, and the _H2 gas rate during the reduction process is 4500mL/(g·h); the _H2 content of the reducing gas is 100% (volume content); the system pressure during the reduction process is 0.1MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 5.0MPa, the reaction temperature is 260°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 4800mL/(g·h), the liquid feed flow rate is 2.4mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 100g/L.

It was detected that in the 0.1Pt/ _CoMoO4 catalyst after reduction, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst, the molar content of ^Co0 was 14%, the molar content of Co-O-Mo was 43%, and the molar content of _MoOx was 41%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using this catalyst is shown in Table 6.

Table 6 Product distribution of hydrogenolysis of sorbitol over 0.1Pt/CoMoO ₄ catalyst

Example 7

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 0.4mmol CoCl ₂ as a cobalt source and 0.6mmol (NH ₄ ) ₂ MoO ₄ as a molybdenum source, dissolve them together in 60mL deionized water, and stir to fully dissolve the two solutions;

2) The mixed solution prepared in step 1) was transferred to a three-necked flask and continuously stirred under water bath heating at a stirring rate of 240 rpm. When the temperature rose to 60° C., 100 mL of anhydrous ethanol was added dropwise to the three-necked flask at a dropping rate of 1.0 mL/min.

3) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 75° C. and stirred for 5 h;

4) separating the precipitate obtained in step 3) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

5) placing the precipitate obtained in step 4) in a drying oven and drying at 120° C. for 12 h;

6) placing the solid sample dried in step 5) in a muffle furnace and calcining it at 400° C. for 2 h at a heating rate of 2° C./min to obtain a catalyst intermediate;

7) dissolving platinum diamine dinitrite in a small amount of ethylene glycol, stirring to make it uniform, and loading the solution onto the catalyst intermediate prepared in step 6) by an excess impregnation method, and then standing the loaded catalyst intermediate in a negative pressure environment for 20 minutes to ensure that the noble metal is uniformly loaded on the catalyst surface, and controlling the Pt content to account for 0.05wt% of the total weight of the cobalt-molybdenum catalyst; then placing it in a drying oven and drying it at 120°C for 12 hours;

8) placing the dried sample obtained in step 7) in a muffle furnace and calcining it at 450° C., maintaining the calcination temperature for 2 hours, to obtain a 0.05Pt/CoMoO ₄ catalyst precursor;

9) granulating the catalyst precursor prepared in step 8) to a particle size of 20-40 mesh;

10) 0.5 g of the catalyst precursor of step 9) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction starts, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 350°C, the heating rate is 2°C/min, the reduction time is 12h, and the _H2 gas rate during the reduction process is 4800mL/(g·h); the _H2 content of the reducing gas is 100% (volume content); the system pressure during the reduction process is 0.1MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 3.0MPa, the reaction temperature is 200°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 4200mL/(g·h), the liquid feed flow rate is 12mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 25g/L.

It was detected that in the 0.05Pt/ _CoMoO4 catalyst after reduction, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst, the molar content of ^Co0 was 10%, the molar content of Co-O-Mo was 61%, and the molar content of _MoOx was 27%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using this catalyst is shown in Table 7.

Table 7 Product distribution of hydrogenolysis of sorbitol over 0.05Pt/ _CoMoO4 catalyst

Example 8

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 0.5mmol Co(NO ₃ ) ₂ as a cobalt source and 0.9mmol Na ₂ MoO ₄ as a molybdenum source, dissolve them in 80mL deionized water, and stir to fully dissolve the two solutions;

2) The mixed solution prepared in step 1) was transferred to a three-necked flask and continuously stirred under water bath heating at a stirring rate of 250 rpm. When the temperature rose to 60° C., 100 mL of anhydrous ethanol was added dropwise to the three-necked flask at a dropping rate of 1.2 mL/min.

3) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 70° C. and stirred for 5 h;

4) separating the precipitate obtained in step 3) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

5) placing the precipitate obtained in step 4) in a drying oven and drying at 150° C. for 10 h;

6) placing the solid sample dried in step 5) in a muffle furnace and calcining it at 400° C. for 2 h at a heating rate of 2° C./min to obtain a catalyst intermediate;

7) dissolving platinum diamine dinitrite in a small amount of ethylene glycol, stirring to make it uniform, and loading the solution onto the catalyst intermediate prepared in step 6) by an excess impregnation method, and then standing the loaded catalyst intermediate in a negative pressure environment for 30 minutes to ensure that the noble metal is uniformly loaded on the catalyst surface, and controlling the Pt content to account for 0.5wt% of the total weight of the cobalt-molybdenum catalyst; then placing it in a drying oven and drying it at 150° C. for 10 hours;

8) placing the dried sample obtained in step 7) in a muffle furnace and calcining it at 400° C., maintaining the calcination temperature for 3 hours, to obtain a 0.5Pt/CoMoO ₄ catalyst precursor;

9) granulating the catalyst precursor prepared in step 8) to a particle size of 20-40 mesh;

10) 0.5 g of the catalyst precursor of step 9) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction starts, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 360°C, the heating rate is 2°C/min, the reduction time is 10h, and the _H2 gas rate during the reduction process is 3600mL/(g·h); the _H2 content of the reducing gas is 100% (volume content); the system pressure during the reduction process is 0.1MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 5.0MPa, the reaction temperature is 240°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 5100mL/(g·h), the liquid feed flow rate is 6mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 50g/L.

It was detected that in the 0.5Pt/CoMoO4 _catalyst after reduction, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst, the molar content of ^Co0 was 16%, the molar content of Co-O-Mo was 49%, and the molar content of _MoOx was 31%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using this catalyst is shown in Table 8.

Table 8 Product distribution of hydrogenolysis of sorbitol over 0.5Pt/CoMoO ₄ catalyst

Embodiment 9

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 0.6 mmol (CH ₃ COO) ₂ Co as a cobalt source and 1.1 mmol Na ₂ MoO ₄ as a molybdenum source, dissolve them in 140 mL of deionized water, and stir to fully dissolve the two solutions;

2) The mixed solution prepared in step 1) was transferred to a three-necked flask and continuously stirred under water bath heating at a stirring rate of 220 rpm. When the temperature rose to 65° C., 100 mL of anhydrous ethanol was added dropwise to the three-necked flask at a dropping rate of 1.0 mL/min.

3) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 80° C. and stirred for 4 h;

4) separating the precipitate obtained in step 3) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

5) placing the precipitate obtained in step 4) in a drying oven and drying at 120° C. for 12 h;

6) placing the solid sample dried in step 5) in a muffle furnace and calcining it at 550° C. for 2 h at a heating rate of 2° C./min to obtain a catalyst intermediate;

7) dissolving platinum diamine dinitrite in a small amount of ethylene glycol, stirring to make it uniform, and loading the solution onto the catalyst intermediate prepared in step 6) by an excessive impregnation method, and then standing the loaded catalyst intermediate in a negative pressure environment for 25 minutes to ensure that the noble metal is uniformly loaded on the catalyst surface, and controlling the Pt content to account for 0.1wt% of the total weight of the cobalt-molybdenum catalyst; then placing it in a drying oven and drying it at 120°C for 12 hours;

8) placing the dried sample obtained in step 7) in a muffle furnace and calcining it at 400° C., maintaining the calcination temperature for 2 hours, to obtain a 0.1Pt/CoMoO ₄ catalyst precursor;

9) granulating the catalyst precursor prepared in step 8) to a particle size of 20-40 mesh;

10) 0.5 g of the catalyst precursor of step 9) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction starts, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 340°C, the heating rate is 2°C/min, the reduction time is 12h, and the _H2 gas rate during the reduction process is 4200mL/(g·h); the _H2 content of the reducing gas is 100% (volume content); the system pressure during the reduction process is 0.1MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 4.0MPa, the reaction temperature is 265°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 4200mL/(g·h), the liquid feed flow rate is 6mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 50g/L.

It was detected that in the 0.1Pt/CoMoO4 _catalyst after reduction, based on the total molar amount of the cobalt-molybdenum component within the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst, the molar content of ^Co0 was 12%, the molar content of Co-O-Mo was 61%, and the molar content of _MoOx was 26%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using this catalyst is shown in Table 9.

Table 9 Product distribution of hydrogenolysis of sorbitol over 0.1Pt/ _CoMoO4 catalyst

Comparative Example 1

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Co ₃ O ₄ and MoO ₃ were weighed in a molar ratio of 1:3, and the two were fully ground for 20 minutes until they were uniformly mixed to obtain a Co&Mo mixed catalyst precursor;

2) granulating the catalyst precursor prepared in step 1) to a particle size of 20-40 mesh;

3) 1 g of catalyst precursor was loaded into a fixed bed reactor and fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction started, the catalyst was pretreated with _H2 for reduction. The reduction temperature was 350°C, the heating rate was 2°C/min, the reduction time was 10h, and the _H2 gas velocity during the reduction process was 4800mL/(g·h); the _H2 content of the reducing gas was 100% (volume content); the system pressure during the reduction process was 0.1MPa; after the reduction was completed, the temperature was lowered to room temperature, the _H2 pressure was increased to 5.0MPa, the reaction temperature was 245°C, the heating rate was 5°C/min, the _H2 flow rate during the reaction was 4200mL/(g·h), the liquid feed flow rate was 6mL/(g·h), and the concentration of the sorbitol solution used in the reaction was 50g/L.

It was detected that in the Co&Mo mixed catalyst after reduction, based on the total molar amount of the cobalt and molybdenum components within the depth range of 3-10nm on the surface of the catalyst, the molar content of ^Co0 was 27%, the molar content of Co-O-Mo was 35%, and the molar content of _MoOx was 37%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using this catalyst is shown in Table 10.

Table 10 Product distribution of hydrogenolysis of sorbitol by Co&Mo mixed catalyst

It can be seen from the above that although the catalyst synthesized by mechanical mixing can generate Co-O-Mo active sites in the reduction stage, due to the low number of active sites, although the catalyst remains stable during the hydrogenolysis of sorbitol to ethanol, the conversion efficiency of the substrate is low, resulting in a continuous decrease in the conversion rate during the reaction.

Comparative Example 2

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Weigh 1mmol (CH ₃ COO) ₂ Co as a cobalt source and 1mmol Na ₂ MoO ₄ as a molybdenum source, dissolve them in 100mL deionized water respectively, and stir to fully dissolve the two solutions;

2) Add the (CH ₃ COO) ₂ Co solution dropwise into the Na ₂ MoO ₄ solution while stirring continuously;

3) The mixed solution prepared in step 2) was transferred to a three-necked flask and continuously stirred under water bath heating at a stirring rate of 300 rpm. When the temperature rose to 60° C., 100 mL of anhydrous ethanol was added dropwise to the three-necked flask at a dropping rate of 0.8 mL/min.

4) After 100 mL of anhydrous ethanol was completely added to the three-necked flask, the preparation system was maintained at 85° C. and stirred for 4 h;

5) separating the precipitate obtained in step 4) from the preparation system by using a suction filtration device, and washing the precipitate with deionized water and anhydrous ethanol;

6) placing the precipitate obtained in step 5) in a drying oven and drying at 120° C. for 12 h;

7) placing the solid sample dried in step 6) in a muffle furnace and calcining it at 500° C. for 3 h at a heating rate of 2° C./min to obtain a CoMoO ₄ catalyst precursor;

8) granulating the catalyst precursor prepared in step 7) to a particle size of 20-40 mesh;

9) 0.5 g of the catalyst precursor of step 8) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction begins, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 350°C, the heating rate is 2°C/min, the reduction time is 10h, and the _H2 gas rate during the reduction process is 4800mL/(g·h); the _H2 content of the reducing gas is 100% (volume content); the system pressure during the reduction process is 0.1MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 5.0MPa, the reaction temperature is 245°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 4200mL/(g·h), the liquid feed flow rate is 6mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 50g/L.

It was detected that in the reduced _CoMoO4 catalyst, based on the total molar amount of the cobalt-molybdenum components within the depth range of 3-10 nm on the surface of the catalyst, the molar content of ^Co0 was 8%, the molar content of Co-O-Mo was 69%, and the molar content of _MoOx was 22%.

The product distribution of the reaction of preparing ethanol by hydrogenolysis of sorbitol using this catalyst is shown in Table 11.

Table 11 Product distribution of hydrogenolysis of sorbitol by _CoMoO4 catalyst

It can be seen from the above that without the introduction of precious metal additives, the catalyst showed excellent conversion rate in the first 4 hours of the reaction, but it can be clearly observed that the decrease in ethanol selectivity also brought about an increase in 1,2-propylene glycol selectivity. This may be due to the lack of contribution of precious metals in the activation of _H2 , which led to changes in the acidic active sites on the catalyst surface, causing sorbitol to isomerize faster after the dehydrogenation reaction, causing the C＝O at the α position to isomerize to the C＝O at the β position, thus leading to an increase in the selectivity of C3 alcohols in the subsequent retro aldol condensation reaction.

Comparative Example 3

A method for converting sorbitol into ethanol by hydrogenolysis reaction using a cobalt-molybdenum catalyst in a continuous fixed-bed reactor, the specific steps are as follows:

1) Co was loaded on MoO ₃ by an impregnation method to prepare a cobalt-molybdenum catalyst, Co(NO ₃ ) ₂ and MoO ₃ were weighed, and the mass of Co metal was 17% of the total mass of the loaded catalyst;

2) Dissolve Co(NO ₃ ) ₂ in a small amount of deionized water and stir to make it evenly dissolved, and load the solution onto MoO ₃ by excessive impregnation method, then place the loaded catalyst precursor in a negative pressure environment for 5 minutes to ensure that the noble metal is evenly loaded on the surface of the catalyst precursor, and then place it in a drying oven for drying at 120°C for 12 hours;

3) placing the solid sample dried in step 2) in a muffle furnace and calcining it at 500° C. for 3 h at a heating rate of 2° C./min to obtain a 17Co/MoO ₃ catalyst precursor;

4) granulating the catalyst precursor prepared in step 3) to a particle size of 20-40 mesh;

5) 0.5 g of the catalyst precursor of step 4) is loaded into a fixed bed reactor, and the catalyst precursor is fixed in the fixed bed reactor with a small amount of quartz wool. Before the reaction starts, the catalyst precursor is pretreated with _H2 for reduction, the reduction temperature is 350°C, the heating rate is 2°C/min, the reduction time is 10h, and the _H2 gas rate during the reduction process is 4800mL/(g·h); the _H2 content of the reducing gas is 100% (volume content); the system pressure during the reduction process is 0.1MPa; after the reduction is completed, the temperature is lowered to room temperature, the _H2 pressure is increased to 5.0MPa, the reaction temperature is 245°C, the heating rate is 5°C/min, the _H2 flow rate during the reaction is 4200mL/(g·h), the liquid feed flow rate is 0.06mL/(g·h), and the concentration of the sorbitol solution used in the reaction is 25g/L.

It was detected that in the 17Co/ _MoO3 catalyst after reduction, based on the total molar amount of the cobalt and molybdenum components within the depth range of 3-10nm on the surface of the catalyst, the molar content of ^Co0 was 23%, the molar content of Co-O-Mo was 38%, and the molar content of _MoOx was 36%.

The product distribution of the reaction of hydrogenolysis of sorbitol to prepare ethanol using this catalyst is shown in Table 12.

Table 12 Product distribution of hydrogenolysis of sorbitol by 17Co/ _MoO3 catalyst

As can be seen from the above, the catalyst prepared by the loading method exhibits similar reaction results to the catalyst prepared by the mechanical mixing method (Comparative Example 1). Since the loading method also generates Co-O-Mo active sites on the catalyst surface, it ensures that Co/ _MoO3 has a higher selectivity for ethanol during the hydrogenolysis of sorbitol to ethanol. However, since the catalyst prepared by the loading method has fewer active sites and the Co/ _MoO3 prepared by the loading method has Co species leaching during the reaction, it leads to the deactivation of the catalyst, thereby causing the sorbitol conversion rate to gradually decrease.

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims (13)

1. A cobalt-molybdenum catalyst is characterized in thatThe cobalt molybdenum catalyst comprises a cobalt molybdenum component comprising: co (Co) ⁰ Co-O-Mo and MoO _x The method comprises the steps of carrying out a first treatment on the surface of the Wherein Co is ⁰ Is positioned in the depth range of 3-10nm of the surface of the cobalt-molybdenum catalyst; co based on the total molar amount of the cobalt-molybdenum component in the depth range of 3-10nm on the surface of the cobalt-molybdenum catalyst ⁰ The molar content of (2) is 25-55%.

2. The cobalt molybdenum catalyst of claim 1, wherein the molar ratio of cobalt to molybdenum in the cobalt molybdenum component is from 1:2 to 2:1.

3. Cobalt molybdenum catalyst according to claim 1 or 2, wherein the molar content of Co-O-Mo is 25-30% in the depth range of 3-10nm of the surface of the cobalt molybdenum catalyst, based on the total molar amount of the cobalt molybdenum component in the depth range of 3-10nm of the surface of the cobalt molybdenum catalyst; and/or the number of the groups of groups,

MoO in the depth range of 3-10nm of the surface of the cobalt molybdenum catalyst based on the total molar amount of the cobalt molybdenum component in the depth range of 3-10nm of the surface of the cobalt molybdenum catalyst _x The molar content of (2) is 45-55%.

4. A cobalt molybdenum catalyst according to any one of claims 1-3, wherein the cobalt molybdenum catalyst further comprises a noble metal component;

Preferably, the noble metal component is selected from at least one of Pt, ru, and Pd;

preferably, the noble metal component is present in an amount of 0.05 to 0.5 wt.%, based on the total weight of the cobalt molybdenum catalyst.

5. The cobalt molybdenum catalyst according to any one of claims 1-4, wherein the cobalt molybdenum catalyst is a microporous-free catalyst; and/or the number of the groups of groups,

the specific surface area of the cobalt-molybdenum catalyst is 10-20m ² /g; and/or the number of the groups of groups,

the bulk density of the cobalt-molybdenum catalyst is 0.8-1.5g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the And/or the number of the groups of groups,

the average particle size of the cobalt-molybdenum catalyst is 20-80 meshes.

6. A method of preparing a catalyst, the method comprising:

s1, mixing a soluble cobalt salt solution and a molybdate solution to form a mixed solution; adding absolute ethyl alcohol to react to obtain a precipitate;

s2, separating, first drying and first roasting the precipitate in sequence to obtain a catalyst intermediate;

and S3, loading a noble metal auxiliary agent salt solution onto the catalyst intermediate by an excessive impregnation method, standing in a negative pressure environment, sequentially performing second drying and second roasting to obtain a cobalt-molybdenum catalyst precursor, and performing aftertreatment to obtain the cobalt-molybdenum catalyst.

7. The preparation method according to claim 6, wherein the molar ratio of cobalt to molybdenum in the mixed solution is 1:2-2:1; and/or the number of the groups of groups,

the volume ratio of the absolute ethyl alcohol to the mixed solution is 1:1-1:2.

8. The production method according to claim 6 or 7, wherein the soluble cobalt salt is selected from at least one of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt sulfate; preferably, the concentration of the soluble cobalt salt is 4-8mmol/L; and/or the number of the groups of groups,

the soluble molybdate is at least one selected from ammonium molybdate, sodium molybdate and potassium molybdate; preferably, the concentration of the soluble molybdate is 7.8 to 12mmol/L; and/or the number of the groups of groups,

the noble metal auxiliary salt is at least one of ruthenium nitrate, ruthenium chloride, rhodium nitrate, palladium nitrate, diammine dinitrate platinum, chloroplatinic acid and chloroauric acid; preferably, the noble metal loading is 0.05 to 0.5wt%.

9. The preparation method according to any one of claims 6 to 8, wherein the reaction is carried out under water bath conditions at a reaction temperature of 80 to 90 ℃ for a reaction time of 3 to 5 hours; and/or the number of the groups of groups,

the temperature of the first drying is 100-120 ℃ and the time is 12-24 hours; and/or the number of the groups of groups,

the temperature of the first roasting is 400-550 ℃ and the time is 2-6h; and/or the number of the groups of groups,

The second drying temperature is 100-120 ℃ and the second drying time is 12-24 hours; and/or the number of the groups of groups,

the temperature of the second roasting is 400-550 ℃ and the time is 2-6h.

10. The production method according to any one of claims 6 to 9, wherein the post-treatment comprises: granulating the cobalt molybdenum catalyst precursor, and then reducing;

preferably, the particle size of the granulation is in the range of 20-80 mesh;

preferably, the temperature of the reduction is 200-400 ℃ and the time is 6-12h, H ₂ Airspeed is 3000-4800 mL/(g.h); h for reduction ₂ The content is 100-5% (volume content); the pressure of the system in the reduction process is 0.1-3MPa.

11. A cobalt molybdenum catalyst prepared by the method of any one of claims 7 to 10.

12. Use of the cobalt molybdenum catalyst according to any one of claims 1-6 and 11 in the production of ethanol by sorbitol hydrogenolysis.

13. A method for producing ethanol by sorbitol hydrogenolysis, comprising: subjecting an aqueous sorbitol solution to a hydrogenolysis reaction with hydrogen in the presence of the cobalt molybdenum catalyst of any one of claims 1-6 and 11;

preferably, the concentration of the sorbitol aqueous solution is 20-60g/L;

preferably, the liquid space velocity of the sorbitol solution is 2.4-12 mL/(g.h), and the gas space velocity of hydrogen is 1800-5400 mL/(g.h);

Preferably, the temperature of the hydrogenolysis reaction is 200-285 ℃ and the pressure is 3-5MPa.