Preparation method of nickel-cerium biochar catalyst

Abstract

A nickel-cerium biochar catalyst is defined, comprising biochar as the carrier and nickel (Ni) and cerium (Ce) as active components with contents of 1-10 wt% each, the balance being biochar. A method

Description

28 11 24 TECHNICAL FIELD

[01] The present disclosure relates to the field of lignin degradation, in particular to a preparation method of a nickel-cerium biochar catalyst. BACKGROUND ART

[02] Lignocellulosic biomass is mainly composed of cellulose, hemicellulose, and lignin, of which lignin accounts for 15-20%. It is the only non-fossil energy source in nature that provides aryl compounds, which is abundant, renewable and inexpensive, and can be continuously converted into chemicals, fuels and carbon materials. Lignin is considered as a waste in the pulp and paper industry and biorefining, and is rarely utilized on a large scale due to its irregular polymeric structure and unreactiveness. In most cases, it is directly burned as low-value energy, which not only wastes resources but also pollutes the air. From the perspective of improving resource utilization, catalytic depolymerization of lignin to prepare high value-added aromatic compounds can not only reduce the dependence on fossil energy, but also obtain higher economic benefits and contribute to environmental protection.

[03] The efficient depolymerization of lignin requires a catalyst with coexisting metal active sites and adsorption sites, which can selectively break C-0 and C-C bonds and adsorb intermediates to prevent further repolymerization. However, the existing problems mainly focus on insufficient depolymerization and heteropoly of depolymerization products. Ni has a well-known excellent hydrogenation performance, and oxides of Ce are rich in oxygen vacancies. Oxygen vacancies are considered to be important active sites in the depolymerization of lignin. Therefore, nickel-cerium bimetal loading on the biochar with large specific surface area and enriched defect sites is beneficial to the bimetallic synergistic catalysis of lignin.

[04] At present, the chemical conversion methods of catalytic depolymerization of lignin mainly include catalytic pyrolysis, catalytic hydrogenolysis, catalytic oxidation, etc. The main problems faced by catalytic pyrolysis include low yield of small molecules, easy coking and carbon deposition of catalysts, complex and difficult purification of products, and high oxygen content and high freezing point of products, which cannot replace fossil fuels. Most of the catalytic hydrogenolysis use precious metals and molecular hydrogen, which have high cost and strict equipment requirements. The catalytic oxidation can significantly reduce the activation energy and achieve efficient depolymerization, but the use of oxidants may not only lead to excessive oxidation of the product, but also increase the oxygen content of the depolymerized product, which is not conducive to the use as the commercial fuel. SUMMARY

[05] In order to solve the deficiencies mentioned in the above background art, a purpose of the present disclosure is to provide a preparation method of a nickel-cerium biochar catalyst.

[06] An object of the present disclosure can be realized through the following technical 28 11 24 schemes:

[07] A method for preparing a nickel-cerium biochar catalyst comprises the steps of:

[08] SI. dissolving lignin with an organic solvent in a nitrogen atmosphere to obtain a lignin solution, spin-drying the lignin solution to obtain a solid, calcining the solid at 200-400 °C under a carbon dioxide atmosphere for 1-4 hours to obtain a calcined solid, and grinding the calcined solid to obtain a biochar carrier as a powder; wherein the organic solvent comprises one of ethanol, ethylene glycol and dimethyl sulfoxide;

[09] S2. dissolving a precursor salt of nickel and a precursor salt of cerium in deionized water to form a solution I, then adding a calcined biochar thereto, and heating and stirring to form a suspension II; and

[10] S3, subjecting the suspension II to sealing and aging treatment, vacuum drying and calcination in sequence to obtain the nickel-cerium biochar catalyst;

[11] wherein the nickel-cerium biochar catalyst comprises biochar as a carrier and an active component loaded on the biochar;

[12] the active component is nickel and cerium; and

[13] the nickel content is 10 wt%, the cerium content is 5 wt%, and the balance is the biochar.

[14] Further, dissolving the lignin is carried out at 100-200°C in a nitrogen atmosphere, and a dissolution time is 1-4 hours.

[15] Further, the precursor salt of nickel includes one of nickel acetylacetonate, anhydrous nickel carbonate, nickel nitrate hexahydrate, and nickel acetate tetrahydrate; and

[16] the precursor salt of cerium includes one of cerium carbonate, cerium nitrate hexahydrate, cerium isopropoxide, cerium acetylacetonate hydrate, and cerium oxalate hydrate.

[17] Further, the sealing and aging treatment in S3 is conducted by treating the suspension II in a mud state at a constant temperature of 50-65°C for 24-48 hours under a protection of nitrogen;

[18] the vacuum drying in S3 is conducted by drying step by step, wherein, first placing an aged suspension in a metal bath to dry for 8-16 hours at 60-110°C; and then drying in a vacuum drying oven for 24-36 hours; and

[19] the calcination in S3 is conducted by heating to 500-800°C at a heating rate of 2-7°C / minute and treating at a constant temperature for 2-6 hours under a nitrogen atmosphere.

[20] Beneficial effects of the present disclosure are as follows:

[21] 1. The nickel-cerium biochar catalyst of the present disclosure uses lignin as the raw material, which widely exists in nature, has low cost and is renewable, can effectively reduce the cost of depolymerization, and is suitable for large-scale industrial application. Moreover, the system of the nickel-cerium biochar catalyst of the present disclosure and the crude glycerol is of great benefit to the green utilization of crude glycerol, an industrial by-product. At the same time, the conversion rate of depolymerized lignin is high, the conversion rate can reach more than 78%, the selectivity of guaiacol and derivatives thereof can exceed 82%, wherein the selectivity of guaiacol is over 41%; 28 11 24

[22] 2. The nickel-cerium biochar catalyst of the present disclosure has carbon carriers with abundant carbon defects and large specific surface area, which is conducive to anchoring metal nanoparticles, and the synergistic effect of nickel and cerium makes the nickel particles evenly dispersed on the cerium dioxide, thereby obtaining better reactive sites and promoting the depolymerization of lignin;

[23] 3. The method for synergistically degrading lignin by the crude glycerol and the catalyst of the present disclosure, which degrades lignin in crude glycerol, has the advantages of easy reaction conditions, low cost, simple operation, strong practicability, environmental friendly, renewable, pollution free, etc., and is suitable for large-scale industrial application. Moreover, the conversion rate of depolymerized lignin is high, the conversion rate can reach more than 78%, the selectivity of guaiacol and derivatives thereof can exceed 82%, wherein the selectivity of guaiacol is more than 41%. The product is easy to separate and can be used in the fine chemical industry such as fragrance, medicine and cosmetics, which can improve the efficient and comprehensive utilization of lignin, while reducing the dependence on fossil resources, and has social benefits of sustainable development. DETAILED DESCRIPTION OF THE EMBODIMENTS

[24] A method for preparing a nickel-cerium biochar catalyst comprises the steps of:

[25] SI. dissolving lignin with an organic solvent in a nitrogen atmosphere to obtain a lignin solution, spin-drying the lignin solution to obtain a solid, calcining the solid at 200-400 °C under a carbon dioxide atmosphere for 1-4 hours to obtain a calcined solid, and grinding the calcined solid to obtain a biochar carrier as a powder; wherein the organic solvent comprises one of ethanol, ethylene glycol and dimethyl sulfoxide;

[26] S2. dissolving a precursor salt of nickel and a precursor salt of cerium in deionized water to form a solution I, then adding a calcined biochar thereto, and heating and stirring to form a suspension II; and

[27] S3, subjecting the suspension II to sealing and aging treatment, vacuum drying and calcination in sequence to obtain the nickel-cerium biochar catalyst;

[28] wherein the nickel-cerium biochar catalyst comprises biochar as a carrier and an active component loaded on the biochar;

[29] the active component is nickel and cerium; and

[30] the nickel content is 10 wt%, the cerium content is 5 wt%, and the balance is the biochar.

[31] Dissolving the lignin is carried out at 100-200°C in a nitrogen atmosphere.

[32] The precursor salt of nickel includes one of nickel acetylacetonate, anhydrous nickel carbonate, nickel nitrate hexahydrate, and nickel acetate tetrahydrate; and the precursor salt of cerium includes one of cerium carbonate, cerium nitrate hexahydrate, cerium isopropoxide, cerium acetylacetonate hydrate, and cerium oxalate hydrate.

[33] The sealing and aging treatment in S3 is conducted by treating the suspension II in a mud state at a constant temperature of 50-65°C for 24-48 hours under a protection of nitrogen.

[34] The vacuum drying in S3 is conducted by drying step by step, wherein, first placing an aged suspension in a metal bath to dry for 8-16 hours at 60-110°C; and then 28 11 24 drying in a vacuum drying oven for 24-36 hours.

[35] The calcination in S3 is conducted by heating to 500-800°C at a heating rate of 2-7°C / minute and treating at a constant temperature for 2-6 hours under a nitrogen atmosphere.

[36] Example 1

[37] Preparation of nickel-cerium biochar catalyst and depolymerization of lignin by crude glycerol system in synergy with nickel-cerium biochar catalyst.

[38] 1. The preparation of nickel-cerium biochar catalyst, comprises the following steps.

[39] The lignin was dissolved in 50 ml of ethylene glycol to conduct a reaction at a constant temperature in a reactor at 180°C for 2 hours in a nitrogen atmosphere to obtain a black-brown molten lignin solution, the solution was spin-dried at 105°C under air to obtain a solid I. The solid I was placed in a tube furnace, heated to 200°C at a heating rate of 2°C / minute, then calcined in a CO2 atmosphere for 1 hour, and ground into powder to obtain a biochar carrier. 1.8842 g of Ni(NOs)2 6H2O and 1.2386 g of Ce(NO3)3 6H2O were added into a 250 mL round bottom beaker, and 100 mL of deionized water was added thereto to dissolve completely to form a solution I. 3.60 g of the calcined biochar was added to the solution I, and stirred in a water bath at 60°C for 24 hours to form a suspension II; followed by increasing a temperature of the suspension II to 95°C, the solution was slowly evaporated to a mud state with a metal bath, and then the mixed system in this state was sealed and left to stand at 55°C for aging for 24 hours. Then the suspension II, after the sealing and aging treatment, was evaporated to dryness in a metal bath to obtain a bulk solid. The bulk solid was dried in a vacuum drying oven at 105°C for 12 hours, then ground and sieved, heated to 700°C at a heating rate of 5°C / minute in a tube furnace, and calcined in a nitrogen atmosphere for 4 hours to obtain a nickel-cerium biochar catalyst with a nickel content of 10 wt% and a cerium content of 10 wt%.

[40] 2 The depolymerization of lignin by the crude glycerol system in synergy with nickel-cerium biochar catalyst, includes the following steps:

[41] 1.0122 g of bamboo lignin and 0.1042 g of catalyst were added into a 100 mL batch high-pressure reactor, and then 30 mL of crude glycerin (a ratio of water to crude glycerin of 1: 1) was added thereto. Then 0.5 MPa high-purity nitrogen was introduced into the reactor, the mixture was stirred at 560 revolutions per minute for 15 minutes, then heated from 24°C to 280°C at a heating rate of 5°C / minute, and the reaction was carried out at this temperature for 3 hours. After completion, the reactor was quickly put into an ice-water bath or liquid nitrogen for quenching and cooling to complete the depolymerization of lignin.

[42] After dropping to normal temperature, a viscous product in the reactor was collected, and subjected to suction filtration using a sand core funnel to separate a solid phase product and a liquid phase product; the solid phase product was washed repeatedly with ethyl acetate, the resulting solid product after washing repeatedly was taken out, and dried in a drying oven at 105°C for 12 hours. An upper oil phase was extracted and separated using a separating funnel, treated with excess solid anhydrous sodium sulfate to remove the water and glycerin, and then filtered to obtain the liquid 28 11 24 phase product of lignin. The liquid phase product was evaporated by a vacuum rotary evaporator to obtain a depolymerized product, which was qualitatively and quantitatively analyzed by GC-MS and GC. It is calculated that the conversion rate of lignin can reach more than 59%, the selectivity of guaiacol and derivatives thereof is more than 72%, wherein the selectivity of guaiacol is more than 26%.

[43] Example 2

[44] Preparation of nickel-cerium biochar catalyst and depolymerization of lignin by crude glycerol system in synergy with nickel-cerium biochar catalyst.

[45] 1. The preparation of nickel-cerium biochar catalyst, comprises the following steps.

[46] The lignin was dissolved in 50 ml of ethylene glycol to conduct a reaction at a constant temperature in a reactor at 150°C for 3 hours in a nitrogen atmosphere to obtain a black-brown molten lignin solution, the solution was spin-dried at 105°C under air to obtain a solid I. The solid I was placed in a tube furnace, heated to 250°C at a heating rate of 3°C / minute, then calcined in a CO2 atmosphere for 2 hours, and ground into powder to obtain a biochar carrier 1.8842 g of NifNChL 6H2O and 0.1239 g of Ce(NO3)3 6H2O were added into a 250 mL round bottom beaker, and 100 mL of deionized water was added thereto to dissolve completely to form a solution I. 3.60 g of the calcined biochar was added to the solution I, and stirred in a water bath at 60°C for 24 hours to form a suspension II; followed by increasing a temperature of the suspension II to 95°C, the solution was slowly evaporated to a mud state with a metal bath, and then the mixed system in this state was sealed and left to stand at 60°C for aging for 32 hours. Then the suspension II, after the sealing and aging treatment, was evaporated to dryness in a metal bath to obtain a bulk solid. The bulk solid was dried in a vacuum drying oven at 105°C for 12 hours, then ground and sieved, heated to 600°C at a heating rate of 2°C / minute in a tube furnace, and calcined in a nitrogen atmosphere for 3 hours to obtain a nickel-cerium biochar catalyst with a nickel content of 10 wt% and a cerium content of 1 wt%.

[47] 2. The depolymerization of lignin by the crude glycerol system in synergy with nickel-cerium biochar catalyst, includes the following steps.

[48] 1.0069 g of bamboo lignin and 0.1012 g of catalyst were added into a 100 mL batch high-pressure reactor, and then 30 mL of crude glycerin (a ratio of water to crude glycerin of 3: 1) was added thereto. Then 0.3 MPa high-purity nitrogen was introduced into the reactor, the mixture was stirred at 650 revolutions per minute for 15 minutes, then heated from 25°C to 260°C at a heating rate of 6°C / minute, and the reaction was carried out at this temperature for 4 hours. After completion, the reactor was quickly put into an ice-water bath or liquid nitrogen for quenching and cooling to complete the depolymerization of lignin.

[49] After dropping to normal temperature, a viscous product in the reactor was collected, and subjected to suction filtration using a sand core funnel to separate a solid phase product and a liquid phase product; the solid phase product was washed repeatedly with ethyl acetate, the resulting solid product after washing repeatedly was taken out, and dried in a drying oven at 105°C for 12 hours. An upper oil phase was extracted and separated using a separating funnel, treated with excess solid anhydrous 28 11 24 sodium sulfate to remove the water and glycerin, and then filtered to obtain the liquid phase product of lignin. The liquid phase product was evaporated by a vacuum rotary evaporator to obtain a depolymerized product, which was qualitatively and quantitatively analyzed by GC-MS and GC. It is calculated that the conversion rate of lignin can reach more than 48%, the selectivity of guaiacol and derivatives thereof is more than 62%, wherein the selectivity of guaiacol is more than 23%.

[50] Example 3

[51] Preparation of nickel-cerium biochar catalyst and depolymerization of lignin by crude glycerol system in synergy with nickel-cerium biochar catalyst.

[52] 1. The preparation of nickel-cerium biochar catalyst, comprises the following steps.

[53] The lignin was dissolved in 50 ml of ethylene glycol to conduct a reaction at a constant temperature in a reactor at 200°C for 4 hours in a nitrogen atmosphere to obtain a black-brown molten lignin solution, the solution was spin-dried at 105°C under air to obtain a solid I. The solid I was placed in a tube furnace, heated to 300°C at a heating rate of 4°C / minute, then calcined in a CO2 atmosphere for 3 hours, and ground into powder to obtain a biochar carrier. 0.9422 g of Ni(NOs)2 6H2O and 1.2383 g of Ce(NO3)s 6H2O were added into a 250 mL round bottom beaker, and 100 mL of deionized water was added thereto to dissolve completely to form a solution I. 3.60 g of the calcined biochar was added to the solution I, and stirred in a water bath at 60°C for 24 hours to form a suspension II; followed by increasing a temperature of the suspension II to 95°C, the solution was slowly evaporated to a mud state with a metal bath, and then the mixed system in this state was sealed and left to stand at 65°C for aging for 28 hours. Then the suspension II, after the sealing and aging treatment, was evaporated to dryness in a metal bath to obtain a bulk solid. The bulk solid was dried in a vacuum drying oven at 105°C for 12 hours, then ground and sieved, heated to 650°C at a heating rate of 6°C / minute in a tube furnace, and calcined in a nitrogen atmosphere for 4 hours to obtain a nickel-cerium biochar catalyst with a nickel content of 5 wt% and a cerium content of 10 wt%.

[54] 2. The depolymerization of lignin by the crude glycerol system in synergy with nickel-cerium biochar catalyst, includes the following steps.

[55] 1.0122 g of bamboo lignin and 0.1042 g of catalyst were added into a 100 mL batch high-pressure reactor, and then 30 mL of crude glycerin (a ratio of water to crude glycerin of 5: 1) was added thereto. Then 0.4 MPa high-purity nitrogen was introduced into the reactor, the mixture was stirred at 700 revolutions per minute for 15 minutes, then heated from 27°C to 310°C at a heating rate of 5°C / minute, and the reaction was carried out at this temperature for 8 hours. After completion, the reactor was quickly put into an ice-water bath or liquid nitrogen for quenching and cooling to complete the depolymerization of lignin.

[56] After dropping to normal temperature, a viscous product in the reactor was collected, and subjected to suction filtration using a sand core funnel to separate a solid phase product and a liquid phase product; the solid phase product was washed repeatedly with ethyl acetate, the resulting solid product, after washing repeatedly, was taken out, and dried in a drying oven at 105°C for 12 hours. An upper oil phase was 28 11 24 extracted and separated using a separating funnel, treated with excess solid anhydrous sodium sulfate to remove the water and glycerin, and then filtered to obtain the liquid phase product of lignin. The liquid phase product was evaporated by a vacuum rotary evaporator to obtain a depolymerized product, which was qualitatively and quantitatively analyzed by GC-MS and GC. It is calculated that the conversion rate of lignin can reach more than 66%, the selectivity of guaiacol and derivatives thereof is more than 74%, wherein the selectivity of guaiacol is more than 29%.

[57] Example 4

[58] Preparation of nickel-cerium biochar catalyst and depolymerization of lignin by crude glycerol system in synergy with nickel-cerium biochar catalyst.

[59] 1. The preparation of nickel-cerium biochar catalyst, comprises the following steps.

[60] The lignin was dissolved in 50 ml of ethylene glycol to conduct a reaction at a constant temperature in a reactor at I8O°C for 2.5 hours in a nitrogen atmosphere to obtain a black-brown molten lignin solution. The solution was spin-dried at 105°C under air to obtain a solid I. The solid I was placed in a tube furnace, heated to 400°C at a heating rate of 5°C / minute, then calcined in a CO2 atmosphere for 1 hour, and ground into powder to obtain a biochar carrier. 1.8842 g of Ni(NOs)2 6H2O and 0.6197 g of Ce(NO3)3 6H2O were added into a 250 mL round bottom beaker, and 100 mL of deionized water was added thereto to dissolve completely to form a solution I. 3.60 g of the calcined biochar was added to the solution I, and stirred in a water bath at 60°C for 24 hours to form a suspension II; followed by increasing a temperature of the suspension II to 95°C, the solution was slowly evaporated to a mud state with a metal bath, and then the mixed system in this state was sealed and left to stand at 50°C for aging for 36 hours. Then the suspension II, after the sealing and aging treatment, was evaporated to dryness in a metal bath to obtain a bulk solid. The bulk solid was dried in a vacuum drying oven at 105°C for 12 hours, then ground and sieved, heated to 500°C at a heating rate of 3°C / minute in a tube furnace, and calcined in a nitrogen atmosphere for 5 hours to obtain a nickel-cerium biochar catalyst with a nickel content of 10 wt% and a cerium content of 5 wt%.

[61] 2. The depolymerization of lignin by the crude glycerol system in synergy with nickel-cerium biochar catalyst, includes the following steps.

[62] 1.0103 g of bamboo lignin and 0.1002 g of catalyst were added into a 100 mL batch high-pressure reactor, and then 30 mL of crude glycerin (a ratio of water to crude glycerin of 6: 1) was added thereto. Then 0.7 MPa high-purity nitrogen was introduced into the reactor, the mixture was stirred at 580 revolutions per minute for 15 minutes, then heated from 30°C to 290°C at a heating rate of 5°C / minute, and the reaction was carried out at this temperature for 7 hours. After completion, the reactor was quickly put into an ice-water bath or liquid nitrogen for quenching and cooling to complete the depolymerization of lignin.

[63] After dropping to normal temperature, a viscous product in the reactor was collected, and subjected to suction filtration using a sand core funnel to separate a solid phase product and a liquid phase product. The solid phase product was washed repeatedly with ethyl acetate, the resulting solid product, after washing repeatedly, was 28 11 24 taken out, and dried in a drying oven at 105°C for 12 hours. An upper oil phase was extracted and separated using a separating funnel, treated with excess solid anhydrous sodium sulfate to remove the water and glycerin, and then filtered to obtain the liquid phase product of lignin. The liquid phase product was evaporated by a vacuum rotary evaporator to obtain a depolymerized product, which was qualitatively and quantitatively analyzed by GC-MS and GC. It is calculated that the conversion rate of lignin can reach more than 72%, the selectivity of guaiacol and derivatives thereof is more than 82%, wherein the selectivity of guaiacol is more than 41%.

[64] Example 5

[65] Preparation of Ni-Cerium biochar catalyst and depolymerization of lignin by crude glycerol system with Ni-Cerium biochar catalyst.

[66] 1 The preparation of nickel-cerium biochar catalyst, comprises the following steps.

[67] The lignin was dissolved in 50 ml of ethylene glycol to conduct a reaction at a constant temperature in a reactor at 180°C for 3.5 hours in a nitrogen atmosphere to obtain a black-brown molten lignin solution. The solution was spin-dried at 105°C under air to obtain a solid I. The solid I was placed in a tube furnace, heated to 350°C at a heating rate of 3°C / minute, then calcined in a CO2 atmosphere for 1 hour, and ground into powder to obtain a biochar carrier. 0.1882 g of NifNQyh 6H2O and 1.2390 g of CelNOah 6H2O were added into a 250 mL round bottom beaker, and 100 mL of deionized water was added thereto to dissolve completely to form a solution I. 3.60 g of the calcined biochar was added to the solution I, and stirred in a water bath at 60°C for 24 hours to form a suspension II; followed by increasing a temperature of the suspension II to 95°C, the solution was slowly evaporated to a mud state with a metal bath, and then the mixed system in this state was sealed and left to stand at 55°C for aging for 30 hours. Then the suspension II, after the sealing and aging treatment, was evaporated to dryness in a metal bath to obtain a bulk solid. The bulk solid was dried in a vacuum drying oven at 105°C for 12 hours, then ground and sieved, heated to 800°C at a heating rate of 7°C / minute in a tube furnace, and calcined in a nitrogen atmosphere for 2 hours to obtain a nickel-cerium biochar catalyst with a nickel content of 1 wt% and a cerium content of 10 wt%.

[68] 2. The depolymerization of lignin by the crude glycerol system in synergy with nickel-cerium biochar catalyst, includes the following steps.

[69] 1.0113 g of bamboo lignin and 0.1025 g of catalyst were added into a 100 mL batch high-pressure reactor, and then 30 mL of crude glycerin (a ratio of water to crude glycerin of 9: I) was added thereto. Then 0.5 MPa high-purity nitrogen was introduced into the reactor, the mixture was stirred at 620 revolutions per minute for 15 minutes, then heated from 28°C to 320°C at a heating rate of 5°C / minute, and the reaction was carried out at this temperature for 10 hours. After completion, the reactor was quickly put into an ice-water bath or liquid nitrogen for quenching and cooling to complete the depolymerization of lignin.

[70] After dropping to normal temperature, a viscous product in the reactor was collected, and subjected to suction filtration using a sand core funnel to separate a solid phase product and a liquid phase product. The solid phase product was washed 28 11 24 repeatedly with ethyl acetate. The resulting solid product, after washing repeatedly, was taken out, and dried in a drying oven at 105°C for 12 hours. An upper oil phase was extracted and separated using a separating funnel, treated with excess solid anhydrous sodium sulfate to remove the water and glycerin, and then filtered to obtain the liquid phase product of lignin. The liquid phase product was evaporated by a vacuum rotary evaporator to obtain a depolymerized product, which was qualitatively and quantitatively analyzed by GC-MS and GC. It is calculated that the conversion rate of lignin can reach more than 68%, the selectivity of guaiacol and derivatives thereof is more than 79%, wherein the selectivity of guaiacol is more than 37%.

[71] In summary:

[72] The nickel-cerium biochar catalyst of the present disclosure uses lignin as the raw material, which widely exists in nature, has low cost and is renewable, can effectively reduce the cost of depolymerization, and is suitable for large-scale industrial application. Moreover, the system of the nickel-cerium biochar catalyst of the present disclosure and the crude glycerol is of great benefit to the green utilization of crude glycerol, an industrial by-product. At the same time, the conversion rate of depolymerized lignin is high, the conversion rate can reach more than 78%, the selectivity of guaiacol and derivatives thereof can exceed 82%, wherein the selectivity of guaiacol is over 41%; the product is easy to separate and can be used in the fine chemical industry such as fragrance, medicine and cosmetics, which can improve the efficient and comprehensive utilization of lignin, while reducing the dependence on fossil resources, and has social benefits of sustainable development.

Claims

28 11 241. A method for preparing a nickel-cerium biochar catalyst, comprising the steps of:SI. dissolving lignin with an organic solvent in a nitrogen atmosphere to obtain a lignin solution, spin-drying the lignin solution to obtain a solid, calcining the solid at 200-400 °C under a carbon dioxide atmosphere for 1-4 hours to obtain a calcined solid, and grinding the calcined solid to obtain a biochar carrier as a powder; wherein the organic solvent comprises one of ethanol, ethylene glycol and dimethyl sulfoxide;S2. dissolving a precursor salt of nickel and a precursor salt of cerium in deionized water to form a solution I, then adding a calcined biochar thereto, and heating and stirring to form a suspension II; andS3, subjecting the suspension II to sealing and aging treatment, vacuum drying and calcination in sequence to obtain the nickel-cerium biochar catalyst;wherein the nickel-cerium biochar catalyst comprises biochar as a carrier and an active component loaded on the biochar,the active component is nickel and cerium; andthe nickel content is 10 wt%, the cerium content is 5 wt%, and the balance is the biochar.

2. The method for preparing the nickel-cerium biochar catalyst according to claim 1, wherein dissolving the lignin is carried out at 100-200°C in a nitrogen atmosphere, and a dissolution time is 1-4 hours.

3. The method for preparing the nickel-cerium biochar catalyst according to claim 1 or claim 2, wherein the precursor salt of nickel includes one of nickel acetylacetonate, anhydrous nickel carbonate, nickel nitrate hexahydrate, and nickel acetate tetrahydrate;and wherein the precursor salt of cerium includes one of cerium carbonate, cerium nitrate hexahydrate, cerium isopropoxide, cerium acetylacetonate hydrate, and cerium oxalate hydrate.

4. The method for preparing the nickel-cerium biochar catalyst according to any of claims 1 to 3, wherein the sealing and aging treatment in S3 is conducted by treating the suspension II in a mud state at a constant temperature of 50-65°C for 24-48 hours under a protection of nitrogen;wherein the vacuum drying in S3 is conducted by drying step by step, by first placing an aged suspension in a metal bath to dry for 8-16 hours at 60-110°C, and then drying in a vacuum drying oven for 24-36 hours;and wherein the calcination in S3 is conducted by heating to 500-800°C at a heating rate of 2-7°C per minute and treating at a constant temperature for 2-6 hours under a nitrogen atmosphere.