Catalyst, preparation method and method for efficiently synthesizing 3-methylpyridine

Abstract

The invention provides a catalyst, a preparation method and a method for efficiently synthesizing 3-methylpyridine, and belongs to the technical field of organic synthesis.2-methylvaleronitrile is subjected to a hydrogenation dehydrogenation reaction under the action of the catalyst, and a product 3-methylpyridine and a byproduct amino-3-methylpyridine are prepared. According to the present invention, the 3-methylpyridine is directly prepared by using the 2-methylglutaronitrile as the raw material and carrying out the hydrogenation reaction and the dehydrogenation reaction under the action of the same catalyst, such that the synthesis route is simple and efficient, the product selectivity is high, no intermediate by-product or impurity is generated, the metal element doped in the catalyst system is economical, efficient and easily available, the catalyst activity is extremely high, and the method is suitable for industrial production. Compared with other technologies, complicated rectification, separation and purification procedures are not needed, the economic benefit is greatly improved, and industrial mass production can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a catalyst, a preparation method and a method for efficiently synthesizing 3-methylpyridine. Background Art

[0002] Methylpyridine, also known as β-methylpyridine and 3-picolin, is an organic synthesis intermediate and solvent. It is a colorless oily liquid with an unpleasant odor. It is miscible with water, ethanol, and ether. It is flammable when exposed to open flames, high temperatures, and oxidants; it produces toxic nitrogen oxide gas when heated. In pesticides, it is used as an intermediate for the insecticides imidacloprid and acetamiprid, and is used to synthesize the next intermediate 3-methylpyridine-N-oxide. It can also be used as a pharmaceutical intermediate, dye intermediate, resin intermediate, etc.

[0003] Patents GB1488335A, US4521602A, CN101990532A and CN107365257A all use 2-methylglutaronitrile as the starting material, and react to generate 2-methyl-1,5-pentanediamine, 3-methylpiperidine and 3-methylpyridine under the catalytic action of metal Ni, Pd / Al2O3, Raney nickel or Raney cobalt doped with other elements. Among them, under the action of nickel-based catalysts or cobalt-based catalysts, the reaction products are mainly composed of 2-methyl-1,5-pentanediamine and 3-methylpiperidine, and also contain a large amount of secondary amines and tertiary amines as by-products. Moreover, nickel-based catalysts and cobalt-based catalysts are generally used in reactors, which are not suitable for continuous production in industry. Under the action of metal Pd, the products obtained are composed of 3-methylpiperidine and 3-methylpyridine, with a total yield of about 83%. However, Pd is easily deactivated in the hydrogenation reaction of 2-methylglutaronitrile. Frequent catalyst regeneration will reduce the catalyst activity and is not conducive to reducing production costs.

[0004] Chinese patent CN107983398B discloses a production method of a nano-attapulgite composite catalyst for the preparation of 3-methylpyridine, the steps are as follows: adding the nano-attapulgite ore to a hydrochloric acid aqueous solution for separation and washing, then washing with a silver nitrate solution, then heating and boiling with distilled water, centrifugal washing, to obtain acid-modified nano-attapulgite; then mixing with a zeolite molecular sieve, drying and grinding, high-temperature calcination, to obtain a nano-attapulgite composite carrier; then adding the composite carrier to a silica sol for full adsorption, drying and grinding to obtain a nano-attapulgite composite catalyst. This invention has a complex process flow, high cost consumption, and is not suitable for industrial production. Summary of the invention

[0005] The purpose of the present invention is to provide a catalyst, a preparation method and a method for efficiently synthesizing 3-methylpyridine. 2-methylglutaronitrile is used as a raw material, and hydrogenation and dehydrogenation reactions are carried out under the action of the same catalyst to directly prepare 3-methylpyridine. The synthesis route is simple and efficient, the product selectivity is high, no intermediate by-products and impurities are generated, and the metal elements doped in the catalyst system are economical, efficient and easy to obtain, the catalyst activity is extremely high, and compared with other technologies, no complicated distillation and separation and purification processes are required, the economic benefits are greatly improved, and industrial mass production can be achieved.

[0006] The technical solution of the present invention is achieved in this way: The present invention provides a method for preparing a catalyst, and the method for preparing the catalyst is as follows: S1. Preparation of S-doped Ni-Al composite layered metal oxide: nickel nitrate, aluminum nitrate and thiourea were dissolved in water, alkali solution was added dropwise, heated for crystallization, filtered, washed, dried and calcined to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped Ni-Al composite layered metal oxide / SiO2 composite: adding tetraethyl orthosilicate to ethanol, adding S-doped Ni-Al composite layered metal oxide, stirring and mixing, dropping ammonia water, heating to react, filtering, washing, and drying to obtain S-doped Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: adding concentrated nitric acid and copper nitrate to water to prepare a mixed solution A, adding the S-doped-Ni-Al composite layered metal oxide / SiO2 composite and ammonium tungstate to water, stirring to dissolve, to prepare a mixed solution B, adding the mixed solution A dropwise to the mixed solution B, stirring to carry out a coprecipitation reaction, filtering, washing, drying, and calcining to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4 reduction: The S-doped W / Cu oxide-loaded -Ni-Al composite layered metal oxide / SiO2 composite was reduced by low-temperature hydrogen to obtain a S-doped W / Cu-loaded -Ni-Al composite layered metal oxide / SiO2 composite; S5. Preparation of catalyst: Add W / Cu loaded S-doped-Ni-Al composite layered metal oxide / SiO2 complex to anhydrous ethanol, add chloroplatinic acid ethanol solution, stir at room temperature, add polyvinyl pyrrolidone and sodium borohydride, stir to react, wash, and dry to obtain a catalyst.

[0007] As a further improvement of the present invention, the molar ratio of nickel nitrate, aluminum nitrate and thiourea in step S1 is 1:1:0.05-0.1, the pH value of the solution is adjusted to 7.5-8.5 by dropping alkali solution, the heating crystallization temperature is 85-95°C, the time is 20-40min, and the calcination temperature is 500-600°C, and the time is 2-4h.

[0008] As a further improvement of the present invention, in step S2, the mass ratio of tetraethyl orthosilicate, S-doped-Ni-Al composite layered metal oxide and ammonia water is 10-12:17-25:2-3, the temperature of the heating reaction is 40-50°C, and the time is 10-12h.

[0009] As a further improvement of the present invention, the concentration of the concentrated nitric acid in step S3 is 5.5-6 mol / L, the mass ratio of the concentrated nitric acid to copper nitrate is 1-2:7-10, the mass ratio of the S-doped-Ni-Al composite layered metal oxide / SiO2 composite and ammonium tungstate is 10-12:5-7, the coprecipitation reaction time is 0.5-1h, the calcination temperature is 300-400°C, and the time is 1-3h.

[0010] As a further improvement of the present invention, the low-temperature hydrogen reduction in step S4 is carried out by introducing hydrogen into a strong drainage ventilated tubular furnace at 650-750° C. for 2-4 hours, with a hydrogen ventilation rate of 15-20 L / min.

[0011] As a further improvement of the present invention, the mass ratio of the S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu, chloroplatinic acid, polyvinyl pyrrolidone and sodium borohydride in step S5 is 15-20:3-5:1.2-1.5:1.9-2.2, and the stirring reaction time is 3-5h.

[0012] As a further improvement of the present invention, the present invention specifically comprises the following steps: S1. Preparation of S-doped Ni-Al composite layered metal oxide: dissolve 1 molar equivalent of nickel nitrate, 1 molar equivalent of aluminum nitrate, and 0.05-0.1 molar equivalent of thiourea in water, add 10-15wt% NaOH solution to adjust the solution pH to 7.5-8.5, heat to 85-95°C, crystallize for 20-40min, filter, wash, dry, and calcine at 500-600°C for 2-4h to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped-Ni-Al composite layered metal oxide / SiO2 composite: add 10-12 parts by weight of tetraethyl orthosilicate to ethanol, add 17-25 parts by weight of S-doped-Ni-Al composite layered metal oxide, stir and mix evenly, drop 2-3 parts by weight of ammonia water, heat to 40-50°C, react for 10-12h, filter, wash, and dry to obtain S-doped-Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: 1-2 parts by weight of 5.5-6 mol / L concentrated nitric acid and 7-10 parts by weight of copper nitrate are added to water to obtain a mixed solution A, 10-12 parts by weight of S-doped-Ni-Al composite layered metal oxide / SiO2 composite and 5-7 parts by weight of ammonium tungstate are added to water, stirred and dissolved to obtain a mixed solution B, the mixed solution A is added dropwise to the mixed solution B, stirred for a coprecipitation reaction for 0.5-1h, filtered, washed, dried, and calcined at 300-400°C for 1-3h to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4. Reduction: The S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide is reduced by introducing hydrogen into a strong drainage permeable tube furnace at 650-750°C for 2-4h, with a hydrogen flow rate of 15-20L / min, to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu; S5. Preparation of catalyst: Add 15-20 parts by weight of W / Cu loaded S-doped-Ni-Al composite layered metal oxide / SiO2 complex to anhydrous ethanol, add 3-5 parts by weight of chloroplatinic acid in an ethanol solution, stir at room temperature for 0.5-1h, add 1.2-1.5 parts by weight of polyvinyl pyrrolidone and 1.9-2.2 parts by weight of sodium borohydride, stir the reaction for 3-5h, wash, and dry to obtain a catalyst.

[0013] The present invention further protects a catalyst prepared by the above preparation method.

[0014] The present invention further protects a method for efficiently synthesizing 3-methylpyridine, wherein 2-methylvaleronitrile is subjected to a hydrogenation-dehydrogenation reaction under the action of the above catalyst to obtain the product 3-methylpyridine, and the by-product is amino-3-methylpyridine.

[0015] As a further improvement of the present invention, the reaction temperature is 250-300° C., the hydrogen-nitrile ratio is 1000-1400, and the 2-methylvaleronitrile is 2-methylvaleronitrile with a purity of >99.9%.

[0016] The present invention has the following beneficial effects: 1. The present invention adopts a coprecipitation method to prepare a composite metal layered oxide, which is doped with S element. The S atoms occupy the octahedral gaps of the active metal Ni particles, breaking the continuous Ni sites while absorbing Ni electrons, and constructing a Ni with isolated surface sites. δ+ -S active center, thus showing excellent activity, selectivity and stability in hydrogenation reactions. δ+ -S active center promotes the activation of hydrogen molecules, and the intermediate is adsorbed in a weak π bond mode, so it is easy to desorb from the active site, which improves the activity of dehydrogenation. Furthermore, a layer of silica is coated on the surface by a sol-gel reaction, which not only greatly improves the mechanical properties of the catalyst, but also increases the specific surface area of ​​the catalyst, increases the reaction site, and promotes the catalytic activity of the reaction. The silica on the surface can also form hydrogen bonds to make it uniformly adsorb tungsten copper oxide, and after reduction, W / Cu catalytic active centers are obtained. Further through the reaction, Pt is loaded on the surface. The larger specific surface area can increase the Pt loading amount, prevent Pt agglomeration and shedding, and can also promote its catalytic activity and durability; 2. The catalyst prepared by the present invention has a high Pt loading and a strong action force, which is beneficial to prevent the agglomeration and shedding of active metals, improve the durability of the catalyst, and has high catalytic activity. Repeated catalysis still maintains good catalytic activity and good dispersibility, and has broad application prospects; 3. The present invention uses 2-methylglutaronitrile as a raw material, performs hydrogenation and dehydrogenation reactions under the action of the same catalyst, and directly prepares 3-methylpyridine. The synthetic route is simple and efficient, the product selectivity is high, no intermediate by-products and impurities are generated, and the metal elements doped in the catalyst system are economical, efficient and easy to obtain, and the catalyst activity is extremely high. Compared with other technologies, there is no need to perform complex distillation and separation and purification processes, which greatly improves the economic benefits and can be industrialized and mass-produced. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example 1 A method for preparing a catalyst comprises the following steps: S1. Preparation of S-doped Ni-Al composite layered metal oxide: 20 mmol nickel nitrate, 20 mmol aluminum nitrate, and 1 mmol thiourea were dissolved in 200 mL water, 10 wt% NaOH solution was added dropwise to adjust the solution pH to 7.5, heated to 85 ° C, crystallized for 20 min, filtered, washed, dried, and calcined at 500 ° C for 2 h to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped-Ni-Al composite layered metal oxide / SiO2 composite: 10 g of tetraethyl orthosilicate was added to 100 mL of ethanol, and 17 g of S-doped-Ni-Al composite layered metal oxide was added, and the mixture was stirred for 10 min, and 2 g of ammonia water was added dropwise, and the mixture was heated to 40° C., reacted for 10 h, filtered, washed, and dried to obtain S-doped-Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: 0.1 g of 5.5 mol / L concentrated nitric acid and 0.7 g of copper nitrate were added to 20 mL of water to prepare a mixed solution A, 1 g of S-doped-Ni-Al composite layered metal oxide / SiO2 composite and 0.5 g of ammonium tungstate were added to 80 mL of water, stirred to dissolve, and a mixed solution B was prepared, and the mixed solution A was added dropwise to the mixed solution B, and the coprecipitation reaction was carried out by stirring for 0.5 h, filtered, washed, dried, and calcined at 300° C. for 1 h to prepare a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4. Reduction: The S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide was reduced by introducing hydrogen into a strong drainage permeable tube furnace at 650°C for 2h with a hydrogen flow rate of 15L / min to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu; S5. Preparation of catalyst: Add 15 g of S-doped-Ni-Al composite layered metal oxide / SiO2 complex loaded with W / Cu into 200 mL of anhydrous ethanol, add 50 mL of ethanol solution containing 3 g of chloroplatinic acid, stir at room temperature for 0.5 h, add 1.2 g of polyvinyl pyrrolidone and 1.9 g of sodium borohydride, stir and react for 3 h, wash, and dry to obtain a catalyst.

[0019] Example 2 A method for preparing a catalyst comprises the following steps: S1. Preparation of S-doped Ni-Al composite layered metal oxide: 20 mmol nickel nitrate, 20 mmol aluminum nitrate, and 2 mmol thiourea were dissolved in 200 mL water, 15 wt% NaOH solution was added dropwise to adjust the solution pH to 8.5, heated to 95 ° C, crystallized for 40 min, filtered, washed, dried, and calcined at 600 ° C for 4 h to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped Ni-Al composite layered metal oxide / SiO2 composite: 12 g of tetraethyl orthosilicate was added to 100 mL of ethanol, and 25 g of S-doped Ni-Al composite layered metal oxide was added, and the mixture was stirred for 10 min, and 3 g of ammonia water was added dropwise, and the mixture was heated to 50° C., reacted for 12 h, filtered, washed, and dried to obtain a S-doped Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: 0.2 g 6 mol / L concentrated nitric acid and 1 g copper nitrate were added to 20 mL water to prepare a mixed solution A, 1.2 g S-doped-Ni-Al composite layered metal oxide / SiO2 composite and 0.7 g ammonium tungstate were added to 80 mL water, stirred to dissolve, and a mixed solution B was prepared, the mixed solution A was added dropwise to the mixed solution B, and the coprecipitation reaction was carried out by stirring for 1 hour, filtered, washed, dried, and calcined at 400°C for 3 hours to prepare a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4. Reduction: The S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide was reduced by introducing hydrogen into a strong drainage permeable tube furnace at 750°C for 4h with a hydrogen flow rate of 20L / min to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu; S5. Preparation of catalyst: Add 20 g of S-doped-Ni-Al composite layered metal oxide / SiO2 complex loaded with W / Cu into 200 mL of anhydrous ethanol, add 50 mL of ethanol solution containing 5 g of chloroplatinic acid, stir at room temperature for 1 h, add 1.5 g of polyvinyl pyrrolidone and 2.2 g of sodium borohydride, stir and react for 5 h, wash, and dry to obtain a catalyst.

[0020] Example 3 A method for preparing a catalyst comprises the following steps: S1. Preparation of S-doped Ni-Al composite layered metal oxide: 20 mmol nickel nitrate, 20 mmol aluminum nitrate, and 1.5 mmol thiourea were dissolved in 200 mL water, 12 wt% NaOH solution was added dropwise to adjust the solution pH to 8, heated to 90 ° C, crystallized for 30 min, filtered, washed, dried, and calcined at 550 ° C for 3 h to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped-Ni-Al composite layered metal oxide / SiO2 composite: 11 g of tetraethyl orthosilicate was added to 100 mL of ethanol, and 20 g of S-doped-Ni-Al composite layered metal oxide was added, and the mixture was stirred for 10 min, and 2.5 g of ammonia water was added dropwise, and the mixture was heated to 45° C., and reacted for 11 h, and then filtered, washed, and dried to obtain S-doped-Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: 0.15 g of 5.7 mol / L concentrated nitric acid and 0.85 g of copper nitrate were added to 50 mL of water to prepare a mixed solution A, 1.1 g of S-doped-Ni-Al composite layered metal oxide / SiO2 composite and 0.6 g of ammonium tungstate were added to 80 mL of water, stirred to dissolve, and a mixed solution B was prepared, the mixed solution A was added dropwise to the mixed solution B, and the coprecipitation reaction was carried out by stirring for 1 hour, filtered, washed, dried, and calcined at 350° C. for 2 hours to prepare a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4. Reduction: The S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide was reduced by introducing hydrogen into a strong drainage permeable tube furnace at 700°C for 3h with a hydrogen flow rate of 17L / min to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu; S5. Preparation of catalyst: Add 17 g of W / Cu loaded S-doped-Ni-Al composite layered metal oxide / SiO2 complex to 200 mL of anhydrous ethanol, add 50 mL of ethanol solution containing 4 g of chloroplatinic acid, stir at room temperature for 1 h, add 1.35 g of polyvinyl pyrrolidone and 2 g of sodium borohydride, stir and react for 4 h, wash, and dry to obtain a catalyst.

[0021] Comparative Example 1 Compared with Example 3, the difference is that thiourea is not added in step S1.

[0022] The details are as follows: S1. Preparation of Ni-Al composite layered metal oxide: Dissolve 20mmol nickel nitrate and 20mmol aluminum nitrate in 200mL water, add 12wt% NaOH solution to adjust the solution pH to 8, heat to 90℃, crystallize for 30min, filter, wash, dry, and calcine at 550℃ for 3h to obtain Ni-Al composite layered metal oxide.

[0023] Comparative Example 2 Compared with Example 3, the difference is that step S2 is not performed.

[0024] A method for preparing a catalyst comprises the following steps: S1. Preparation of S-doped Ni-Al composite layered metal oxide: 20 mmol nickel nitrate, 20 mmol aluminum nitrate, and 1.5 mmol thiourea were dissolved in 200 mL water, 12 wt% NaOH solution was added dropwise to adjust the solution pH to 8, heated to 90 ° C, crystallized for 30 min, filtered, washed, dried, and calcined at 550 ° C for 3 h to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped-Ni-Al composite layered metal oxide / SiO2 composite: 11 g of tetraethyl orthosilicate was added to 100 mL of ethanol, and 20 g of S-doped-Ni-Al composite layered metal oxide was added, and the mixture was stirred for 10 min, and 2.5 g of ammonia water was added dropwise, and the mixture was heated to 45° C., and reacted for 11 h, and then filtered, washed, and dried to obtain S-doped-Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: 0.15 g of 5.7 mol / L concentrated nitric acid and 0.85 g of copper nitrate were added to 50 mL of water to prepare a mixed solution A, 1.1 g of S-doped-Ni-Al composite layered metal oxide / SiO2 composite and 0.6 g of ammonium tungstate were added to 80 mL of water, stirred to dissolve, and a mixed solution B was prepared, the mixed solution A was added dropwise to the mixed solution B, and the coprecipitation reaction was carried out by stirring for 1 hour, filtered, washed, dried, and calcined at 350° C. for 2 hours to prepare a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4. Reduction: The S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide was reduced by introducing hydrogen into a strong drainage permeable tube furnace at 700°C for 3h with a hydrogen flow rate of 17L / min to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu; S5. Preparation of catalyst: Add 17 g of W / Cu loaded S-doped-Ni-Al composite layered metal oxide / SiO2 complex to 200 mL of anhydrous ethanol, add 50 mL of ethanol solution containing 4 g of chloroplatinic acid, stir at room temperature for 1 h, add 1.35 g of polyvinyl pyrrolidone and 2 g of sodium borohydride, stir and react for 4 h, wash, and dry to obtain a catalyst.

[0025] Comparative Example 3 Compared with Example 3, the difference is that steps S3 and S4 are not performed.

[0026] A method for preparing a catalyst comprises the following steps: S1. Preparation of S-doped Ni-Al composite layered metal oxide: 20 mmol nickel nitrate, 20 mmol aluminum nitrate, and 1.5 mmol thiourea were dissolved in 200 mL water, 12 wt% NaOH solution was added dropwise to adjust the solution pH to 8, heated to 90 ° C, crystallized for 30 min, filtered, washed, dried, and calcined at 550 ° C for 3 h to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped-Ni-Al composite layered metal oxide / SiO2 composite: 11 g of tetraethyl orthosilicate was added to 100 mL of ethanol, and 20 g of S-doped-Ni-Al composite layered metal oxide was added, and the mixture was stirred for 10 min, and 2.5 g of ammonia water was added dropwise, and the mixture was heated to 45° C., and reacted for 11 h, and then filtered, washed, and dried to obtain S-doped-Ni-Al composite layered metal oxide / SiO2 composite; S3. Preparation of catalyst: Add 17 g S-doped-Ni-Al composite layered metal oxide / SiO2 complex into 200 mL anhydrous ethanol, add 50 mL ethanol solution containing 4 g chloroplatinic acid, stir at room temperature for 1 h, add 1.35 g polyvinyl pyrrolidone and 2 g sodium borohydride, stir and react for 4 h, wash, and dry to obtain the catalyst.

[0027] Comparative Example 4 Compared with Example 3, the difference is that step S4 is not performed.

[0028] A method for preparing a catalyst comprises the following steps: S1. Preparation of S-doped Ni-Al composite layered metal oxide: 20 mmol nickel nitrate, 20 mmol aluminum nitrate, and 1.5 mmol thiourea were dissolved in 200 mL water, 12 wt% NaOH solution was added dropwise to adjust the solution pH to 8, heated to 90 ° C, crystallized for 30 min, filtered, washed, dried, and calcined at 550 ° C for 3 h to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped-Ni-Al composite layered metal oxide / SiO2 composite: 11 g of tetraethyl orthosilicate was added to 100 mL of ethanol, and 20 g of S-doped-Ni-Al composite layered metal oxide was added, and the mixture was stirred for 10 min, and 2.5 g of ammonia water was added dropwise, and the mixture was heated to 45° C., and reacted for 11 h, and then filtered, washed, and dried to obtain S-doped-Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: 0.15 g of 5.7 mol / L concentrated nitric acid and 0.85 g of copper nitrate were added to 50 mL of water to prepare a mixed solution A, 1.1 g of S-doped-Ni-Al composite layered metal oxide / SiO2 composite and 0.6 g of ammonium tungstate were added to 80 mL of water, stirred to dissolve, and a mixed solution B was prepared, the mixed solution A was added dropwise to the mixed solution B, and the coprecipitation reaction was carried out by stirring for 1 hour, filtered, washed, dried, and calcined at 350° C. for 2 hours to prepare a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4. Preparation of catalyst: Add 17 g of S-doped-Ni-Al composite layered metal oxide / SiO2 complex loaded with W / Cu oxide into 200 mL of anhydrous ethanol, add 50 mL of ethanol solution containing 4 g of chloroplatinic acid, stir at room temperature for 1 h, add 1.35 g of polyvinyl pyrrolidone and 2 g of sodium borohydride, stir and react for 4 h, wash, and dry to obtain a catalyst.

[0029] Comparative Example 5. Compared with Embodiment 3, the difference is that step S5 is not performed.

[0030] A method for preparing a catalyst comprises the following steps: S1. Preparation of S-doped Ni-Al composite layered metal oxide: 20 mmol nickel nitrate, 20 mmol aluminum nitrate, and 1.5 mmol thiourea were dissolved in 200 mL water, 12 wt% NaOH solution was added dropwise to adjust the solution pH to 8, heated to 90 ° C, crystallized for 30 min, filtered, washed, dried, and calcined at 550 ° C for 3 h to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped-Ni-Al composite layered metal oxide / SiO2 composite: 11 g of tetraethyl orthosilicate was added to 100 mL of ethanol, and 20 g of S-doped-Ni-Al composite layered metal oxide was added, and the mixture was stirred for 10 min, and 2.5 g of ammonia water was added dropwise, and the mixture was heated to 45° C., and reacted for 11 h, and then filtered, washed, and dried to obtain S-doped-Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: 0.15 g of 5.7 mol / L concentrated nitric acid and 0.85 g of copper nitrate were added to 50 mL of water to prepare a mixed solution A, 1.1 g of S-doped-Ni-Al composite layered metal oxide / SiO2 composite and 0.6 g of ammonium tungstate were added to 80 mL of water, stirred to dissolve, and a mixed solution B was prepared, the mixed solution A was added dropwise to the mixed solution B, and the coprecipitation reaction was carried out by stirring for 1 hour, filtered, washed, dried, and calcined at 350° C. for 2 hours to prepare a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4. Reduction: The S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide was reduced by passing hydrogen into a strong drainage and permeable tubular furnace at 700°C for 3 hours with a hydrogen flow rate of 17 L / min to obtain a W / Cu-loaded S-doped-Ni-Al composite layered metal oxide / SiO2 composite, which is a catalyst.

[0031] Test Example 1 The specific surface area and total pore volume of the catalysts prepared in Examples 1-3 and Comparative Examples 1-5 were measured using a 3-FLEX 3500 multi-station high-throughput gas adsorption instrument. The results are shown in Table 1.

[0032] Table 1

[0033] It can be seen from the above table that the catalysts prepared in Examples 1-3 of the present invention have larger specific surface areas and total pore volumes.

[0034] Catalyst test: 1.0 g of the above solid catalyst was weighed and used in a micro fixed bed reactor at a reaction temperature of 250-300° C. to synthesize 3-methylpyridine; the sample was analyzed by an Agilent 7820 gas chromatograph. The results are shown in Table 2 below.

[0035] Example 4 2-methylvaleronitrile is subjected to a hydrogenation-dehydrogenation reaction under the action of a catalyst, the reaction temperature is 250° C., the hydrogen-nitrile ratio is 1000, the 2-methylvaleronitrile is 2-methylvaleronitrile with a purity of> 99.9%, the liquid hourly space velocity is 2 / h, the catalyst is the catalyst prepared in Example 1, and the addition amount is 50% of the total volume of the system, and the product 3-methylpyridine is obtained, and the by-product is amino-3-methylpyridine.

[0036] Example 5 2-methylvaleronitrile is subjected to a hydrogenation-dehydrogenation reaction under the action of a catalyst, the reaction temperature is 300° C., the hydrogen-nitrile ratio is 1400, the 2-methylvaleronitrile is 2-methylvaleronitrile with a purity of> 99.9%, the liquid hourly space velocity is 2 / h, the catalyst is the catalyst prepared in Example 2, and the addition amount is 50% of the total volume of the system, and the product 3-methylpyridine is obtained, and the by-product is amino-3-methylpyridine.

[0037] Example 6 The present embodiment provides a method for efficiently synthesizing 3-methylpyridine, wherein 2-methylvaleronitrile is subjected to a hydrogenation-dehydrogenation reaction under the action of a catalyst, the reaction temperature is 280° C., the hydrogen-nitrile ratio is 1300, the 2-methylvaleronitrile is 2-methylvaleronitrile with a purity of> 99.9%, the liquid hourly space velocity is 2 / h, the catalyst is the catalyst prepared in Example 3, the addition amount is 1wt% of the total mass of the system, and the product 3-methylpyridine is obtained, and the by-product is amino-3-methylpyridine.

[0038] Comparative Example 6 Compared with Example 6, the difference is that the catalyst is the catalyst prepared in Comparative Example 1.

[0039] Comparative Example 7 Compared with Example 6, the difference is that the catalyst is the catalyst prepared in Comparative Example 2.

[0040] Comparative Example 8 Compared with Example 6, the difference is that the catalyst is the catalyst prepared in Comparative Example 3.

[0041] Comparative Example 9 Compared with Example 6, the difference is that the catalyst is the catalyst prepared in Comparative Example 4.

[0042] Comparative Example 10 Compared with Example 6, the difference is that the catalyst is the catalyst prepared in Comparative Example 5.

[0043] Test Example 2 The methods for preparing 3-methylpyridine in Examples 4-6 and Comparative Examples 6-10 were analyzed. The results are shown in Table 2.

[0044] Table 2

[0045] As can be seen from the above table, the conversion rate of 2-methylvaleronitrile in the methods of Examples 4-6 of the present invention is high, and the selectivity for producing 3-methylpyridine is good.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a catalyst, characterized in that: The preparation method of the catalyst is as follows: S1. Preparation of S-doped Ni-Al composite layered metal oxide: nickel nitrate, aluminum nitrate and thiourea were dissolved in water, alkali solution was added dropwise, heated for crystallization, filtered, washed, dried and calcined to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped Ni-Al composite layered metal oxide / SiO2 composite: adding tetraethyl orthosilicate to ethanol, adding S-doped Ni-Al composite layered metal oxide, stirring and mixing, dropping ammonia water, heating to react, filtering, washing, and drying to obtain S-doped Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: adding concentrated nitric acid and copper nitrate to water to prepare a mixed solution A, adding the S-doped-Ni-Al composite layered metal oxide / SiO2 composite and ammonium tungstate to water, stirring to dissolve, to prepare a mixed solution B, adding the mixed solution A dropwise to the mixed solution B, stirring to carry out a coprecipitation reaction, filtering, washing, drying, and calcining to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4 reduction: The S-doped W / Cu oxide-loaded -Ni-Al composite layered metal oxide / SiO2 composite was reduced by low-temperature hydrogen to obtain a S-doped W / Cu-loaded -Ni-Al composite layered metal oxide / SiO2 composite; S5. Preparation of catalyst: Add W / Cu loaded S-doped-Ni-Al composite layered metal oxide / SiO2 complex to anhydrous ethanol, add chloroplatinic acid ethanol solution, stir at room temperature, add polyvinyl pyrrolidone and sodium borohydride, stir to react, wash, and dry to obtain a catalyst.

2. The method according to claim 1, characterized in that In step S1, the molar ratio of nickel nitrate, aluminum nitrate and thiourea is 1:1:0.05-0.1, the pH value of the solution is adjusted to 7.5-8.5 by dropping alkali solution, the heating crystallization temperature is 85-95°C, the time is 20-40min, and the calcination temperature is 500-600°C, and the time is 2-4h.

3. The method according to claim 1, characterized in that In step S2, the mass ratio of tetraethyl orthosilicate, S-doped-Ni-Al composite layered metal oxide and ammonia water is 10-12:17-25:2-3, the temperature of the heating reaction is 40-50° C., and the time is 10-12 hours.

4. The method according to claim 1, characterized in that: The concentration of the concentrated nitric acid in step S3 is 5.5-6 mol / L, the mass ratio of the concentrated nitric acid to copper nitrate is 1-2:7-10, the mass ratio of the S-doped-Ni-Al composite layered metal oxide / SiO2 composite to ammonium tungstate is 10-12:5-7, the coprecipitation reaction time is 0.5-1h, the calcination temperature is 300-400°C, and the time is 1-3h.

5. The method according to claim 1, characterized in that The low-temperature hydrogen reduction in step S4 is carried out by introducing hydrogen into a strong drainage permeable tubular furnace at 650-750° C. for 2-4 hours, with a hydrogen ventilation rate of 15-20 L / min.

6. The method according to claim 1, characterized in that In step S5, the mass ratio of the W / Cu loaded S-doped-Ni-Al composite layered metal oxide / SiO2 composite, chloroplatinic acid, polyvinyl pyrrolidone and sodium borohydride is 15-20:3-5:1.2-1.5:1.9-2.2, and the stirring reaction time is 3-5h.

7. The method according to claim 1, characterized in that The specific steps include: S1. Preparation of S-doped Ni-Al composite layered metal oxide: dissolve 1 molar equivalent of nickel nitrate, 1 molar equivalent of aluminum nitrate, and 0.05-0.1 molar equivalent of thiourea in water, add 10-15wt% NaOH solution to adjust the solution pH to 7.5-8.5, heat to 85-95°C, crystallize for 20-40min, filter, wash, dry, and calcine at 500-600°C for 2-4h to obtain S-doped Ni-Al composite layered metal oxide; S2. Preparation of S-doped-Ni-Al composite layered metal oxide / SiO2 composite: add 10-12 parts by weight of tetraethyl orthosilicate to ethanol, add 17-25 parts by weight of S-doped-Ni-Al composite layered metal oxide, stir and mix evenly, drop 2-3 parts by weight of ammonia water, heat to 40-50°C, react for 10-12h, filter, wash, and dry to obtain S-doped-Ni-Al composite layered metal oxide / SiO2 composite; S3. S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide: 1-2 parts by weight of 5.5-6 mol / L concentrated nitric acid and 7-10 parts by weight of copper nitrate are added to water to obtain a mixed solution A, 10-12 parts by weight of S-doped-Ni-Al composite layered metal oxide / SiO2 composite and 5-7 parts by weight of ammonium tungstate are added to water, stirred and dissolved to obtain a mixed solution B, the mixed solution A is added dropwise to the mixed solution B, stirred for a coprecipitation reaction for 0.5-1h, filtered, washed, dried, and calcined at 300-400°C for 1-3h to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide; S4. Reduction: The S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu oxide is reduced by introducing hydrogen into a strong drainage permeable tube furnace at 650-750°C for 2-4h, with a hydrogen flow rate of 15-20L / min, to obtain a S-doped-Ni-Al composite layered metal oxide / SiO2 composite loaded with W / Cu; S5. Preparation of catalyst: Add 15-20 parts by weight of W / Cu loaded S-doped-Ni-Al composite layered metal oxide / SiO2 complex to anhydrous ethanol, add 3-5 parts by weight of chloroplatinic acid in an ethanol solution, stir at room temperature for 0.5-1h, add 1.2-1.5 parts by weight of polyvinyl pyrrolidone and 1.9-2.2 parts by weight of sodium borohydride, stir the reaction for 3-5h, wash, and dry to obtain a catalyst.

8. A catalyst prepared by the method according to any one of claims 1 to 7.

9. A method for efficiently synthesizing 3-methylpyridine, characterized in that: 2-methylvaleronitrile is subjected to a hydrogenation-dehydrogenation reaction under the action of the catalyst described in claim 8 to obtain the product 3-methylpyridine, and the by-product is amino-3-methylpyridine.

10. The method according to claim 9, characterized in that The reaction temperature is 250-300° C., the hydrogen-nitrile ratio is 1000-1400, and the 2-methylvaleronitrile is 2-methylvaleronitrile with a purity of >99.9%.

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