Carbon-coated nickel catalyst, preparation thereof and application thereof in hydrogenation of glucose to sorbitol

Abstract

The application discloses a carbon-coated nickel catalyst and a preparation method and application thereof in preparation of sorbitol from glucose by hydrogenation. The preparation method comprises the following steps: step one, preparing a supported nickel catalyst; step two, uniformly mixing the supported nickel catalyst with water, adding a soluble sugar carbon source compound, vacuum drying until the water is dried after room temperature immersion for 4-10 hours, to obtain a dry product; and finally obtaining the carbon-coated nickel catalyst by calcining the dry product at 400-900 DEG C under N2 atmosphere for 4-10 hours. The application provides the application of the carbon-coated nickel catalyst in preparation of sorbitol from glucose by hydrogenation, and the carbon-coated nickel catalyst has good stability and target product selectivity.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology and relates to a carbon-coated nickel catalyst, its preparation method, and its application in the hydrogenation of glucose to prepare sorbitol. Background Technology

[0002] Catalytic hydrogenation is a crucial step in the production of many bulk and fine chemicals. When reactants contain multiple reducible functional groups, selective hydrogenation of specific groups is required to produce high-value chemicals. Supported nanomaterial catalysts are among the most important hydrogenation catalysts and have wide applications in industrial production. However, under harsh reaction conditions, catalysts are prone to deactivation due to coking, sintering, poisoning, and leaching of active components. These phenomena not only increase costs in industrial production but also severely affect the quality of high-end fine chemicals such as pharmaceuticals and electronic chemicals.

[0003] Inventing a supported noble metal catalyst with good catalytic hydrogenation activity and stability in harsh environments is of profound significance. Researchers have proposed completely encapsulating transition metals (TMs) in a graphene shell to prevent direct contact between the metal and the external environment. This encapsulated catalyst involves encapsulating nanomaterials within a graphene shell. The internal nanoparticles and the outer graphene shell interact strongly through chemical bonds or other forces. The graphene shell acts as a barrier in the catalytic reaction, preventing oxidation, loss, and aggregation of the encapsulated nanoparticles.

[0004] Sorbitol, as the most widely used polyol in the food, pharmaceutical, cosmetic, and chemical industries, has broad development prospects as a humectant, sweetener, texture agent, softener, and in the production of vitamin C. In the industrial production of sorbitol from glucose, catalytic hydrogenation is currently the primary method, using noble metal Ru-based and Ni-based catalysts. While Ru-based catalysts exhibit excellent activity and stability in hydrogenation reactions, their high cost and limited resource reserves make them unsuitable for large-scale industrial applications. Ni-based catalysts, on the other hand, have been a research hotspot due to their low cost, abundant resources, and good hydrogenation activity. However, in the glucose hydrogenation reaction, Ni-based catalysts still suffer from poor stability, easy loss of active components, and oxidation.

[0005] Chinese patent CN 104107691A discloses a novel Ru / CNTs catalyst and its preparation and application method. The method involves using ruthenium trichloride as a metal precursor, dispersed on a modified carbon nanotube support treated with concentrated nitric acid, and adding a reducing agent under strongly mixed alkaline conditions to obtain a Ru / CNTs catalyst with ruthenium as the active component. By controlling the catalyst preparation and reaction conditions, it exhibits higher catalytic activity and selectivity compared to other Ru-based catalysts, and the reaction conditions are milder. However, the production cost of Ru-based catalysts is high, and their stability has not been evaluated.

[0006] Chinese patent CN110465296A discloses a nickel-based glucose catalyst, which is mainly composed of nickel as the main active component, nickel oxide, additives, silicon oxide, and zirconium oxide. First, a catalyst precursor is obtained by microwave-assisted co-precipitation. Then, the catalyst precursor is passivated and reduced to obtain a glucose hydrogenation catalyst. This catalyst overcomes the problem that the reaction solution needs to be adjusted to alkalinity before use, which is a problem of nickel-based catalysts. It also extends the service life of the catalyst to a certain extent. However, after eight trials, the conversion rate of glucose decreased significantly.

[0007] Therefore, based on the above background, it is of great significance to design a low-cost, high-performance Ni-based catalyst for the catalytic hydrogenation of glucose. Summary of the Invention

[0008] The purpose of this invention is to provide a carbon-coated nickel catalyst, its preparation method, and its application in the hydrogenation of glucose to sorbitol.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a carbon-coated nickel catalyst for the hydrogenation of glucose to sorbitol, comprising the following steps:

[0011] Step 1: Preparation of supported nickel catalyst: The support is dispersed in water, and then a nickel precursor solution is added. The mixture is stirred in a water bath at 70-90℃ for 3-6 hours. Then, ammonia is added dropwise to adjust the pH to 12 to fully precipitate nickel ions. After stirring for 0.5-5 hours, the mixture is cooled to room temperature, filtered, washed with water until neutral, and vacuum dried until the water is completely removed to obtain a dried product. The dried product is calcined at 500-800℃ for 4-8 hours in an inert atmosphere or air atmosphere to obtain a calcined product. Finally, the product is transferred to a tube furnace, and a constant H2 gas flow is introduced. The temperature is programmed to rise to 300-500℃ for 3-9 hours to reduce the catalyst, thus obtaining the supported nickel catalyst. The catalyst is then sealed and stored in ethanol.

[0012] Step 2: Mix the supported nickel catalyst with water until homogeneous, add a soluble sugar carbon source compound, impregnate at room temperature for 4-10 hours, and then vacuum dry until the moisture is completely removed to obtain a dried product; calcine the dried product at 400-900℃ for 4-10 hours under N2 atmosphere to finally obtain the desired carbon-coated nickel catalyst; the soluble sugar carbon source compound is selected from one of glucose monohydrate, soluble starch, citric acid monohydrate, PVP, or sucrose; the carbon element in the soluble sugar carbon source compound accounts for 10-50% of the mass of the supported nickel catalyst, preferably 20-50%, more preferably 35-50%, and even more preferably 40-45%.

[0013] In the preparation method of the catalyst described in this invention, the nickel precursor solution is prepared by dissolving the nickel precursor in a solvent. This invention does not have special requirements for the solvent and concentration of the nickel precursor solution; those skilled in the art can prepare it conventionally according to actual needs. For example, the concentration of the nickel precursor solution, calculated as nickel, can be 0.1–0.5 g / mL. The nickel precursor is selected from Ni(NO3)2·6H2O, NiCl2·6H2O, Ni(CH3COO)2·6H2O, or NiSO4·6H2O, etc., preferably Ni(NO3)2·6H2O or NiCl2·6H2O. The solvent depends on the type of nickel compound and can be deionized water, ethanol, etc. This invention does not have special requirements in this regard.

[0014] In the supported nickel catalyst prepared by the present invention, the support for the supported nickel catalyst is activated carbon, SiO2, TiO2 or diatomaceous earth.

[0015] In step one of this invention, the carrier and nickel precursor solution are fed according to the required theoretical nickel loading, specifically, the theoretical nickel loading = m Ni / m 载体 ×100% = 20-45%, preferably 25-45%, more preferably 30-35%; wherein m Ni This refers to the mass of Ni element contained in the nickel precursor solution.

[0016] In the carbon-coated nickel catalyst prepared by the present invention, the surface carbon layer is obtained from different carbon precursors. The carbon precursor is preferably hydrated glucose or soluble starch, and most preferably hydrated glucose.

[0017] In step one of this invention, the vacuum drying temperature is 60–100°C, and the drying time is 10–15 hours.

[0018] In step one of this invention, the obtained dried product is calcined at 500°C for 5 hours in an inert atmosphere or air atmosphere to obtain the calcined product. Finally, it is transferred to a tube furnace, a constant H2 gas flow is introduced, and the temperature is programmed to rise to 400°C for 5 hours for reduction.

[0019] In step two of this invention, the mass ratio of the supported nickel catalyst to water is 1:50 to 300.

[0020] In step two of this invention, the vacuum drying temperature is 60–100°C, and the drying time is 4–15 hours.

[0021] In step two of this invention, during the process of forming a carbon layer by high-temperature roasting, the roasting temperature is 400-900℃, preferably 500-800℃, more preferably 550-650℃, and most preferably 600℃ for 6 hours.

[0022] In this invention, the inert atmosphere is one or more of nitrogen, argon, and helium.

[0023] Secondly, the present invention provides a carbon-coated nickel catalyst prepared according to the preparation method described in the first aspect. The carbon-coated nickel catalyst of the present invention exhibits good catalytic hydrogenation performance in high temperature, high pressure, and weakly acidic solutions.

[0024] Thirdly, the present invention provides the application of the carbon-coated nickel catalyst described in the second aspect in the hydrogenation of glucose to prepare sorbitol.

[0025] The application specifically includes the following steps:

[0026] (1) Using anhydrous glucose as raw material and water as solvent, carbon-coated nickel catalyst is added and mixed evenly, and then transferred to a high-pressure reactor. The mass ratio of carbon-coated nickel catalyst, water and glucose is 0.009 to 0.021: 2 to 5: 1.

[0027] (2) Before heating the reaction, the reaction system is first fully replaced with N2, then with H2. After reaching the reaction temperature, hydrogen gas is introduced to start the reaction. The reaction conditions are: temperature 110–150℃, hydrogen pressure 1.0–5.0 MPa. After the reaction is complete, sorbitol is obtained. In the above application, after the reaction is completed, the reaction solution is filtered and analyzed by gas chromatography to calculate the conversion rate and selectivity of the reaction.

[0028] In this application, increasing the amount of catalyst helps to improve the hydrogenation activity of glucose.

[0029] In the aforementioned application, the reaction temperature is preferably 110–130°C.

[0030] The method for preparing the carbon-coated nickel catalyst of this invention produces Ni particles with small particle size. The outer carbon layer effectively encapsulates the active metal, resulting in high dispersion of Ni metal within the carbon layer. Furthermore, the presence of the surface carbon layer effectively prevents oxidation and loss of the catalyst's active components. While the carbon layer itself does not possess any catalytic hydrogenation activity, the internal Ni NPs transfer electrons through the middle carbon layer to the outermost carbon layer, giving the surface carbon layer a high electron density and thus enabling catalytic hydrogenation. In the process of glucose hydrogenation to sorbitol, H2 is first adsorbed on the electron-rich carbon layer surface. Under the action of the hydrogenation active centers in the carbon layer, active hydrogen atoms H* are generated and rapidly transferred to the substrate glucose, which is also adsorbed on the carbon layer surface, reducing the carbonyl group -C=O to -OH. Under high temperature, high pressure, and weakly acidic reaction environments, the catalyst exhibits good conversion and selectivity while maintaining good long-term cycling stability and regeneration performance.

[0031] Therefore, controlling the thickness, density, and electron transport capability of the carbon layer is crucial to determining the catalyst's performance. Different metal precursors exhibit varying interaction forces with the carbon source compound. This invention, by controlling the carbon source compound, carbonization temperature, and carbonization time, yields suitable carbon layer thickness and structure, facilitating the quantum tunneling effect and resulting in a catalyst with excellent performance under high temperature, high pressure, and weakly acidic conditions.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. Because the nickel catalyst is covered by a carbon layer, the nickel will not be lost, sintered, or oxidized, thus preventing catalyst deactivation, when exposed to high temperature, high pressure, or weakly acidic environments. Therefore, the catalyst of this invention exhibits good stability in harsh reaction environments, and no significant deactivation was observed after eight consecutive reuses.

[0034] 2. The reaction of glucose catalytic hydrogenation to sorbitol using a carbon-coated nickel catalyst in this invention has better stability and selectivity for the target product compared to nickel-based catalysts without carbon coating. Attached Figure Description

[0035] Figure 1 TEM images of the carbon-coated nickel catalyst prepared in Example 6 at different magnifications.

[0036] Figure 2 XRD patterns of the fresh carbon-coated nickel catalyst prepared in Example 6 and the carbon-coated nickel catalyst after 8 uses.

[0037] Figure 3 N2 adsorption-desorption curves and pore size distribution curves of the carbon-coated nickel catalyst prepared in Example 6. Detailed Implementation

[0038] The present invention will be further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0039] The example uses high-performance gas chromatography (HPLC) for quantitative analysis of sorbitol. First, the reacted solution undergoes an acetylation reaction. The specific experimental steps are as follows: 0.2 mL of sample solution is placed in a stoppered test tube, and 0.3 mL of methylimidazole and 2 mL of acetic anhydride are added sequentially. The acetylation reaction is carried out at room temperature for 10 min. Then, 5 mL of distilled water is added to degrade excess acetic anhydride. After cooling to room temperature with running tap water, 1 mL of chloroform is added, and the mixture is shaken to ensure thorough mixing. After standing for 10 min, the upper aqueous phase is removed, and another 3 mL of distilled water is added. After cooling, 1 mL of chloroform is added, and the mixture is allowed to stand for phase separation. The aqueous phase is then removed, and this process is repeated three times. An appropriate amount of anhydrous sodium sulfate is added to the obtained lower chloroform phase for dehydration and drying. After standing for 5 min, a small amount of the solution is taken for HPLC analysis.

[0040] The acetylated samples were analyzed using an Agilent 7890B gas chromatograph manufactured by Agilent Technologies. The optimized chromatographic conditions were as follows: HP-5 capillary column (30m×320μm×0.25μm); initial column temperature set at 180℃, increased to 220℃ at a rate of 4℃ / min, and held at 220℃ for 15min; vaporization chamber temperature set at 270℃; FID flame ionization detector; injection volume of 1μL; carrier gas He, flow rate of 1mL / min, and split ratio of 10:1.

[0041] Example 1

[0042] 1 g of SiO2 support was placed in a beaker, and 50 ml of deionized water was added. Then, 4.25 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 550 °C in air for 4 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 300 °C for 3 h to obtain the Ni / SiO2 catalyst. The catalyst was then sealed and stored in ethanol.

[0043] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.179g of soluble sugar carbon source compound glucose monohydrate, impregnate at room temperature for 10h, and then vacuum dry at 60℃ for 15h until the moisture is dried to obtain the dried product. The dried product is then calcined at 650℃ for 6h under N2 atmosphere to obtain carbon-coated nickel catalyst.

[0044] Example 2

[0045] 1 g of TiO2 support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.47 ml of NiCl2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C for 4 h in a nitrogen atmosphere to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 500 °C for 5 h to obtain the Ni / TiO2 catalyst. The catalyst was then sealed and stored in ethanol.

[0046] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.179g of soluble starch, a soluble sugar carbon source compound, impregnate at room temperature for 8h, and then vacuum dry at 70℃ for 12h until the moisture is dried to obtain the dried product. The dried product is then calcined at 750℃ for 4h under N2 atmosphere to obtain the carbon-coated nickel catalyst.

[0047] Example 3

[0048] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.63 ml of Ni(CH3COO)2·4H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C for 8 h in an argon atmosphere to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 3 h to obtain a Ni / C catalyst. The catalyst was then sealed and stored in ethanol.

[0049] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.252g of soluble sugar carbon source compound citric acid monohydrate, impregnate at room temperature for 5h, and then vacuum dry at 100℃ for 6h until the moisture is dried to obtain the dried product. The dried product is then calcined at 900℃ for 7h under N2 atmosphere to obtain the carbon-coated nickel catalyst.

[0050] Example 4

[0051] 1 g of diatomaceous earth support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.84 ml of NiSO4·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 800 °C for 7 h in a helium atmosphere to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 350 °C for 9 h to obtain a Ni / diatomaceous earth catalyst. The catalyst was then sealed and stored in ethanol.

[0052] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 0.663g of PVP, impregnate at room temperature for 4h, and then vacuum dry at 90℃ for 8h until the moisture is dried to obtain the dried product. The dried product is then calcined at 700℃ for 5h under N2 atmosphere to obtain the carbon-coated nickel catalyst.

[0053] Example 5

[0054] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 2.48 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 700 °C for 7 h in a nitrogen atmosphere to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 300 °C for 4 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0055] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.019g of soluble sugar carbon source compound sucrose, impregnate at room temperature for 4h, and then vacuum dry at 50℃ for 15h until the moisture is dried to obtain the dried product. The dried product is then calcined at 800℃ for 4h under N2 atmosphere to obtain carbon-coated nickel catalyst.

[0056] Example 6

[0057] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.30 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C in air for 5 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 5 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0058] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.179g of soluble sugar carbon source compound glucose monohydrate, impregnate at room temperature for 8h, and then vacuum dry at 70℃ for 12h until the moisture is dried to obtain the dried product. The dried product is then calcined at 600℃ for 6h under N2 atmosphere to obtain the carbon-coated nickel catalyst.

[0059] Example 7

[0060] In a 100 mL autoclave, add 0.1 g of the catalyst prepared in Example 1, 10 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa of N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Heat to 120°C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Start stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 97.4%, and the sorbitol selectivity is 72.0%.

[0061] Example 8

[0062] In a 100 mL autoclave, add 0.2 g of the catalyst prepared in Example 2, 20 g of glucose, and 40 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa of N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 110°C, then purge with hydrogen to maintain a pressure of 5.0 MPa. Begin stirring at a rate of 1000 rpm. After the reaction is complete, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 95.2%, and the sorbitol selectivity is 81.7%.

[0063] Example 9

[0064] In a 100 mL autoclave, add 0.5 g of the catalyst prepared in Example 3, 50 g of glucose, and 50 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa of N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 130°C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 97.3%, and the sorbitol selectivity is 88.6%.

[0065] Example 10

[0066] In a 100 mL autoclave, add 0.4 g of the catalyst prepared in Example 4, 20 g of glucose, and 20 mL of deionized water. Replace the air with nitrogen five times, then purge with 1 MPa of N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen gas. Raise the temperature to 110°C, then purge with hydrogen gas to maintain a pressure of 2.0 MPa. Start stirring at a rate of 1000 rpm. After the reaction is complete, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 95.6%, and the sorbitol selectivity is 83.4%.

[0067] Example 11

[0068] In a 100 mL autoclave, add 0.3 g of the catalyst prepared in Example 5, 10 g of glucose, and 40 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa of N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Heat to 110°C, then purge with hydrogen to maintain a pressure of 1.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 90.8%, and the sorbitol selectivity is 73.0%.

[0069] Example 12

[0070] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Example 6, 20 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa of N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 110°C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After the reaction is complete, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 99.8%, and the sorbitol selectivity is 97.5%.

[0071] Example 13

[0072] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Example 6, 20 g of glucose, and 30 mL of deionized water. Replace the air with nitrogen five times, then purge with 1 MPa of N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen gas. Heat to 110 °C, then purge with hydrogen gas to maintain a pressure of 4.0 MPa. Start stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. Recover the catalyst and perform a reuse experiment under the same reaction conditions. The results are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] Comparative Example 1

[0077] Comparative Example 1 investigated the performance of supported carbon-encapsulated nickel metal catalysts prepared with different carbon sources. Compared with the catalyst in Example 6, replacing the carbon source with soluble starch significantly reduced the selectivity of sorbitol.

[0078] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.30 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C in air for 5 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 5 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0079] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.179g of soluble starch, a soluble sugar carbon source compound, impregnate at room temperature for 8h, and then vacuum dry at 70℃ for 12h until the moisture is dried to obtain the dried product. The dried product is then calcined at 600℃ for 6h under N2 atmosphere to obtain the carbon-coated nickel catalyst.

[0080] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Comparative Example 1, 20 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 110 °C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 96.8%, and the sorbitol selectivity is 77.5%.

[0081] Comparative Example 2

[0082] Comparative Example 2 investigated the performance of a supported carbon-encapsulated nickel metal catalyst prepared at a lower carbonization temperature. Compared with the catalyst in Example 6, lowering the carbonization temperature significantly reduced the selectivity of sorbitol.

[0083] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.30 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C in air for 5 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 5 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0084] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.179g of soluble sugar carbon source compound glucose monohydrate, impregnate at room temperature for 8h, and then vacuum dry at 70℃ for 12h until the moisture is dried to obtain the dried product. The dried product is then calcined at 500℃ for 6h under N2 atmosphere to obtain carbon-coated nickel catalyst.

[0085] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Comparative Example 2, 20 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 110 °C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 95.8%, and the sorbitol selectivity is 78.5%.

[0086] Comparative Example 3

[0087] Comparative Example 3 investigated the performance of a supported carbon-coated nickel metal catalyst prepared at a higher carbonization temperature. Compared with the catalyst in Example 6, increasing the carbonization temperature significantly reduced glucose conversion and sorbitol selectivity.

[0088] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.30 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C in air for 5 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 5 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0089] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.179g of soluble sugar carbon source compound glucose monohydrate, impregnate at room temperature for 8h, and then vacuum dry at 70℃ for 12h until the moisture is dried to obtain the dried product. The dried product is then calcined at 800℃ for 6h under N2 atmosphere to obtain carbon-coated nickel catalyst.

[0090] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Comparative Example 3, 20 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 110 °C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 73.4%, and the sorbitol selectivity is 72.6%.

[0091] Comparative Example 4

[0092] Comparative Example 4 investigated the performance of a supported carbon-encapsulated nickel metal catalyst prepared with fewer carbon sources.

[0093] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.30 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C in air for 5 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 5 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0094] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 0.589g of soluble sugar carbon source compound glucose monohydrate, impregnate at room temperature for 8h, and then vacuum dry at 70℃ for 12h until the moisture is dried to obtain the dried product. The dried product is then calcined at 600℃ for 6h under N2 atmosphere to obtain carbon-coated nickel catalyst.

[0095] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Comparative Example 4, 20 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa of N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 110 °C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 98.4%, and the sorbitol selectivity is 97.6%.

[0096] Comparative Example 5

[0097] Comparative Example 5 investigated the performance of supported carbon-encapsulated nickel metal catalysts prepared from a variety of carbon sources.

[0098] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.30 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C in air for 5 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 5 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0099] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 2.358g of soluble sugar carbon source compound monohydrate glucose, impregnate at room temperature for 8h, and then vacuum dry at 70℃ for 12h until the moisture is dried to obtain the dried product. The dried product is then calcined at 600℃ for 6h under N2 atmosphere to obtain carbon-coated nickel catalyst.

[0100] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Comparative Example 5, 20 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa of N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 110 °C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 93.1%, and the sorbitol selectivity is 94.1%.

[0101] Comparative Example 6

[0102] Comparative Example 6 investigated the performance of a supported carbon-coated nickel metal catalyst prepared with a longer calcination time.

[0103] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.30 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C in air for 5 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 5 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0104] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.179g of soluble sugar carbon source compound glucose monohydrate, impregnate at room temperature for 8h, and then vacuum dry at 70℃ for 12h until the moisture is dried to obtain the dried product. The dried product is then calcined at 600℃ for 10h under N2 atmosphere to obtain the carbon-coated nickel catalyst.

[0105] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Comparative Example 6, 20 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 110 °C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 91.1%, and the sorbitol selectivity is 93.2%.

[0106] Comparative Example 7

[0107] Comparative Example 7 investigated the performance of a supported carbon-coated nickel metal catalyst prepared with a shorter calcination time.

[0108] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.30 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C in air for 5 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 5 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0109] Weigh 1g of the catalyst prepared above, mix it evenly with 50ml of water, add 1.179g of soluble sugar carbon source compound glucose monohydrate, impregnate at room temperature for 8h, and then vacuum dry at 70℃ for 12h until the moisture is dried to obtain the dried product. The dried product is then calcined at 600℃ for 2h under N2 atmosphere to obtain the carbon-coated nickel catalyst.

[0110] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Comparative Example 7, 20 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Raise the temperature to 110 °C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. The glucose conversion rate is 90.3%, and the sorbitol selectivity is 93.5%.

[0111] Comparative Example 8

[0112] Comparative Example 8 investigated the performance of a carbon-free supported nickel catalyst.

[0113] 1 g of activated carbon support was placed in a beaker, and 50 ml of deionized water was added. Then, 3.30 ml of Ni(NO3)2·6H2O with a salt concentration of 0.5 g / mL was added to the above solution and stirred in a water bath at 80 °C for 4 h. Then, a small amount of ammonia water of a certain concentration was slowly added dropwise until the solution pH = 12, and stirring was continued for 4 h. After cooling to room temperature, the solution was filtered, washed with deionized water until neutral, and dried under vacuum at 70 °C for 12 h. The resulting product was then calcined at 500 °C in air for 5 h to obtain a black powder. Finally, the powder was transferred to a tube furnace, and a constant H2 gas flow was introduced. The temperature was programmed to rise to 400 °C for 5 h to obtain the Ni / activated carbon catalyst. The catalyst was then sealed and stored in ethanol.

[0114] In a 100 mL autoclave, add 0.6 g of the catalyst prepared in Comparative Example 8, 20 g of glucose, and 30 mL of deionized water. Replace the air five times with nitrogen, then purge with 1 MPa N2 gas and maintain the pressure for 3-5 minutes, checking the airtightness of the apparatus. If the airtightness is good, vent the gas from the autoclave, then replace the nitrogen in the reactor three times with hydrogen. Heat to 110 °C, then purge with hydrogen to maintain a pressure of 4.0 MPa. Begin stirring at a rate of 1000 rpm. After complete reaction, sorbitol is obtained. Remove the reaction solution, filter to remove the catalyst, and analyze by high-performance gas chromatography. Recover the catalyst and perform a reuse experiment under the same reaction conditions. The results are shown in Table 2.

[0115] Table 2

[0116]

[0117]

Claims

1. The application of a carbon-coated nickel catalyst in the hydrogenation of glucose to sorbitol, characterized in that: The preparation method of the carbon-coated nickel catalyst includes the following steps: Step 1: Preparation of supported nickel catalyst: The support is dispersed in water, and then a nickel precursor solution is added. The mixture is stirred in a water bath at 70-90℃ for 3-6 h. Then, ammonia is added dropwise to adjust the pH to 12 to ensure complete precipitation of nickel ions. Stirring continues for 0.5-5 h, followed by cooling to room temperature, filtration, washing with water until neutral, and vacuum drying until the moisture is completely removed to obtain a dried product. The dried product is calcined at 500-800℃ for 4-8 h in an inert atmosphere or air atmosphere to obtain a calcined product. Finally, the product is transferred to a tube furnace, and a constant H2 gas flow is introduced. The temperature is programmed to rise to 300-500℃ for 3-9 h to reduce the catalyst, thus obtaining the supported nickel catalyst. The support is activated carbon. The support and nickel precursor solution are fed according to the required theoretical nickel loading, specifically, the theoretical nickel loading = m Ni / m 载体 ×100%=25~45%, where m Ni This refers to the mass of Ni element contained in the nickel precursor solution; Step 2: Mix the supported nickel catalyst with water until homogeneous, add soluble sugar carbon source compound, impregnate at room temperature for 4-10 hours, and then vacuum dry until the moisture is removed to obtain the dried product; The resulting dried product was calcined at 550-650℃ for 4-6 hours under N2 atmosphere to finally obtain the desired carbon-coated nickel catalyst; the soluble sugar carbon source compound was selected from glucose monohydrate. The carbon element in the soluble sugar carbon source compound accounts for 20-50% of the mass of the supported nickel catalyst.

2. The application as described in claim 1, characterized in that: The carbon element in the soluble sugar carbon source compound accounts for 35-50% of the mass of the supported nickel catalyst.

3. The application as described in claim 2, characterized in that: The carbon element in the soluble sugar carbon source compound accounts for 40-45% of the mass of the supported nickel catalyst.

4. The application as described in claim 1, characterized in that: In step one, the carrier and nickel precursor solution are fed according to the required theoretical nickel loading, specifically, the theoretical nickel loading = m Ni / m 载体 ×100%=30~35%.

5. The application as described in claim 1, characterized in that: In step one, the obtained dried product is calcined at 500°C for 5 hours in an inert atmosphere or air atmosphere to obtain the calcined product. Finally, it is transferred to a tube furnace, and a constant H2 gas flow is introduced. The temperature is then programmed to rise to 400°C for 5 hours for reduction.

6. The application as described in claim 1, characterized in that: In step two, the mixture is calcined at 600℃ for 6 hours.

7. The application as described in any one of claims 1-6, characterized in that: The application specifically includes the following steps: (1) Using anhydrous glucose as raw material and water as solvent, carbon-coated nickel catalyst is added and mixed evenly, and then transferred to a high-pressure reactor. The mass ratio of carbon-coated nickel catalyst, water and glucose is 0.009 to 0.021: 2 to 5:

1. (2) Before heating the reaction, the reaction system is fully replaced with N2, and then fully replaced with H2. After heating to the reaction temperature, hydrogen gas is introduced to start the reaction. The reaction conditions are: temperature 110~150 ℃, hydrogen pressure 1.0~5.0 MPa. After the reaction is complete, the product sorbitol is obtained.

8. The application as described in claim 7, characterized in that: In this application, the reaction temperature is 110~130 ℃.

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