A supported nickel-based catalyst, its preparation method, and a catalytic separation method for straw components.

Abstract

This invention provides a supported nickel-based catalyst, its preparation method, and a method for catalytic separation of straw components, relating to the field of catalytic materials technology. The supported nickel-based catalyst provided by this invention comprises a bio-based nitrogen-doped carbon support and active metallic nickel supported on the bio-based nitrogen-doped carbon support. The bio-based nitrogen-doped carbon support is obtained by pyrolysis and carbonization of a mixture of straw and mulberry leaves fermented by microbial enzymatic hydrolysis as a nitrogen-containing biomass precursor. This invention utilizes renewable bio-based nitrogen-doped carbon to support nickel. The resulting catalyst, when applied to the catalytic reduction separation of straw components, exhibits high reactivity and good stability, enabling efficient catalytic separation and comprehensive utilization of straw components. This invention also provides a method for catalytic separation of straw components, converting lignin in straw into lignin oil while simultaneously separating the solid product holocellulose. Using the method of this invention for catalytic separation of straw components, the lignin oil yield is greater than 30%, and the solid product recovery rate is greater than 85%.

Description

Technical Field

[0001] This invention relates to the field of catalytic materials technology, and in particular to a supported nickel-based catalyst, its preparation method, and a method for catalytic separation of straw components. Background Technology

[0002] The preparation of fine chemicals from renewable biomass resources can effectively reduce dependence on non-renewable energy sources such as coal, oil, and natural gas, and is one of the technological routes with great development potential and application prospects for developing a green and low-carbon economy. Straw is an important source of biomass resources, and its structural components are mainly composed of cellulose, hemicellulose, and lignin. Cellulose is a linear polymer composed of β-D-glucose units linked by β-1,4-glycosidic bonds. Hemicellulose is mainly an amorphous polymer composed of C-5 and C-6 monosaccharide units. Lignin is mainly a three-dimensional network polymer formed by three phenylpropane-based units: coumarol (H), coniferyl alcohol (G), and sinapyl alcohol (S), linked by C-C and CO bonds. Due to the more complex composition of straw compared to woody plants, the complex structures and interactions between its components, as well as its unique physicochemical properties, pose challenges to the separation of straw components, resulting in limited research on the catalytic separation of straw components.

[0003] In recent years, a new strategy for the effective separation and utilization of biomass components has emerged using catalytic reduction separation methods. This involves using catalytic reactions to degrade lignin in biomass into monomers while preserving the carbohydrate structure. Currently, the separation of straw components mainly employs noble metal catalysts with hydrogenation activity and catalytic reduction reactions in non-organic solvent hydrogen systems. Among non-noble metal catalysts, nickel-based catalysts have the advantages of abundant reserves, low cost, and catalytic activity comparable to noble metal catalysts. For example, the reported nickel-based catalyst Ni / C catalyzed the reduction separation of straw components in methanol solvent at 200℃ for 3 hours, yielding a 24.5% monophenol yield and a 76% holocellulose retention (ACS, Sustainable Chemistry and Engineering, 2016, 4, 6940-6950). However, this nickel-based catalyst suffers from problems such as uneven carbon material distribution and low catalytic performance. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a supported nickel-based catalyst, its preparation method, and a method for catalytic separation of straw components. The supported nickel-based catalyst prepared by this invention exhibits high reactivity when applied to the catalytic reduction and separation of straw components.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a supported nickel-based catalyst, comprising a bio-based nitrogen-doped carbon support and active metallic nickel supported on the bio-based nitrogen-doped carbon support. The bio-based nitrogen-doped carbon support is obtained by pyrolysis and carbonization of a mixture of straw and paper mulberry as a biomass nitrogen-containing precursor through microbial enzymatic hydrolysis and fermentation.

[0007] This invention provides a method for preparing the supported nickel-based catalyst described above, comprising the following steps:

[0008] Straw raw materials were mixed with paper mulberry and subjected to microbial enzymatic hydrolysis to obtain a precursor for bio-based nitrogen-doped carbon materials.

[0009] The bio-based nitrogen-doped carbon material precursor was pyrolyzed and carbonized in an inert atmosphere to obtain the nitrogen-doped carbon material.

[0010] The nitrogen-doped carbon material was impregnated in an aqueous nickel salt solution and then reduced to obtain the supported nickel-based catalyst.

[0011] Preferably, the straw raw material includes straw and / or fiber separated from straw; the paper mulberry and straw raw material are powders with an independent particle size of 120-200 mesh, and the mass ratio of the straw raw material to paper mulberry is 1:99-1:2.

[0012] Preferably, the pyrolysis carbonization temperature is 400–800°C and the time is 1–24 h.

[0013] Preferably, the mass ratio of nickel salt to water in the nickel salt aqueous solution is 1:10 to 1:20, and the nickel salt includes one or more of nickel nitrate, nickel chloride, nickel sulfate, and nickel acetate; the mass ratio of nickel element to nitrogen-doped carbon material in the nickel salt aqueous solution is 1:9 to 1:20.

[0014] Preferably, the impregnation time is 24 to 48 hours; the reduction is carried out in a hydrogen atmosphere at a temperature of 400 to 800°C for 3 to 6 hours.

[0015] This invention provides the application of the supported nickel-based catalyst described in the above technical solutions or the supported nickel-based catalyst prepared by the above technical solutions in the catalytic separation of straw components, wherein the straw components include cellulose, hemicellulose and lignin.

[0016] This invention also provides a method for catalytic separation of straw components, comprising the following steps:

[0017] Straw, alcohol solvent, and catalyst are mixed in a hydrogen atmosphere and subjected to a catalytic reaction to obtain a reaction solution; the catalyst is the supported nickel-based catalyst described in the above technical solution or the supported nickel-based catalyst prepared by the preparation method described in the above technical solution;

[0018] The reaction mixture is subjected to solid-liquid separation to obtain liquid and solid products;

[0019] The solvent was removed from the liquid product to obtain lignin oil;

[0020] The solid product was sieved and separated to obtain holocellulose and the catalyst.

[0021] Preferably, the mass ratio of the catalyst to the straw is 1:1 to 1:5; the alcohol solvent includes one or more of methanol, ethanol, propanol and isopropanol, and the amount ratio of straw to alcohol solvent is (0.1-1) g: (15-25) mL.

[0022] Preferably, the hydrogen pressure of the catalytic reaction is 0.1–10 MPa, the reaction temperature is 200–240 °C, and the reaction time is 1–10 h.

[0023] This invention provides a supported nickel-based catalyst, comprising a bio-based nitrogen-doped carbon support and active metallic nickel supported on the bio-based nitrogen-doped carbon support. The bio-based nitrogen-doped carbon support is obtained by pyrolysis and carbonization of a mixture of straw and mulberry leaves fermented by microbial enzymatic hydrolysis as a nitrogen-containing biomass precursor. This invention utilizes renewable bio-based nitrogen-doped carbon material to support nickel. The resulting catalyst, when applied to the catalytic reduction and separation of straw components, exhibits high reactivity and good stability, enabling efficient catalytic separation and comprehensive utilization of straw components.

[0024] This invention provides a method for preparing the supported nickel-based catalyst described in the above technical solution. The invention uses a mixture of straw and mulberry leaves obtained through microbial enzymatic fermentation as a nitrogen-containing biomass precursor, which is then pyrolyzed and carbonized to obtain a nitrogen-doped carbon support material. The support is then used to prepare the supported nickel-based catalyst via an impregnation reduction method. This invention uses straw as the carbon source and mulberry leaves (rich in protein) and microbial enzymes as the nitrogen source. The biomass raw materials used are abundant in nitrogen, renewable, inexpensive, widely available, and environmentally friendly, requiring no additional nitrogen source. The preparation method provided by this invention is simple, has mild reaction conditions, and produces a uniformly dispersed nickel metal in the catalyst.

[0025] This invention provides a catalytic separation method for straw components. The method utilizes a supported nickel-based catalyst in an alcohol solvent for the catalytic reduction and separation of straw components, converting lignin in the straw into lignin oil. Simultaneously, a solid substance containing cellulose and hemicellulose (i.e., holocellulose) is catalytically separated from the straw components. This invention achieves effective separation of straw components, and the separated holocellulose can be recycled as straw raw material for the preparation of the supported nickel-based catalyst. This invention enables the high-value comprehensive utilization of straw and is beneficial for industrial application. Example results show that using the method of this invention for the catalytic separation of straw components yields a liquid product lignin oil yield of over 30% and a solid product recovery rate of over 85%. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process for preparing the supported nickel-based catalyst and catalytically separating straw components according to the present invention;

[0027] Figure 2 The image shows the GC-MS diagram of the lignin oil obtained in Example 1. Detailed Implementation

[0028] This invention provides a supported nickel-based catalyst, comprising a bio-based nitrogen-doped carbon support and active metallic nickel supported on the bio-based nitrogen-doped carbon support. The bio-based nitrogen-doped carbon support is obtained by pyrolysis and carbonization of a mixture of straw and paper mulberry as a biomass nitrogen-containing precursor through microbial enzymatic hydrolysis and fermentation.

[0029] In this invention, the amount of nitrogen doping in the bio-based nitrogen-doped carbon support is preferably 1 to 6 wt%, and the mass content of active metal nickel in the supported nickel-based catalyst is preferably 5 to 10%.

[0030] This invention provides a method for preparing the supported nickel-based catalyst described above, comprising the following steps:

[0031] Straw raw materials were mixed with paper mulberry and subjected to microbial enzymatic hydrolysis to obtain a precursor for bio-based nitrogen-doped carbon materials.

[0032] The bio-based nitrogen-doped carbon material precursor was pyrolyzed and carbonized in an inert atmosphere to obtain the nitrogen-doped carbon material.

[0033] The nitrogen-doped carbon material was impregnated in an aqueous nickel salt solution and then reduced to obtain the supported nickel-based catalyst.

[0034] Unless otherwise specified, all raw materials involved in this invention are commercially available products well known to those skilled in the art.

[0035] The process for preparing the supported nickel-based catalyst and catalytic separation of straw components according to the present invention is as follows: Figure 1As shown below. A detailed explanation follows.

[0036] This invention involves mixing straw raw materials with paper mulberry and then performing microbial enzymatic hydrolysis to obtain a precursor for bio-based nitrogen-doped carbon materials. In this invention, the straw raw material preferably includes straw and / or fibers separated from the straw. There are no special requirements for the straw used; any straw well-known to those skilled in the art, such as corn straw, can be used. In this invention, the paper mulberry is preferably the leaves of the paper mulberry. In this invention, the straw raw material and paper mulberry are preferably in powder form, with a particle size preferably independently of 120-200 mesh. The powder is preferably obtained by crushing, drying, and grinding the straw raw material and paper mulberry, respectively. In this invention, the mass ratio of straw raw material to paper mulberry is preferably 1:99 to 1:2. In specific embodiments of this invention, the mass ratio of straw raw material to paper mulberry is 1:9, 1:4, or 1:2.3.

[0037] Paper mulberry (Broussonetia papyrifera) is a perennial broad-leaved tree characterized by wide adaptability, rapid growth, drought resistance, exceptional adaptability, high yield, and rich content of crude protein and amino acids, giving it broad economic and social value. Hybrid or wild paper mulberry trees contain up to approximately 26% crude protein and also contain nitrogen-containing compounds such as alkaloids; therefore, paper mulberry is an excellent precursor for natural bio-based nitrogen-doped carbon materials. This invention uses protein-rich paper mulberry as a nitrogen source and straw as a carbon source. By adjusting the ratio of straw to paper mulberry, the nitrogen content in the nitrogen-doped carbon material can be controlled.

[0038] The present invention does not have any special requirements for the method of mixing the paper mulberry and straw raw materials; any mixing method known to those skilled in the art can be used to mix them evenly.

[0039] In this invention, the microbial enzymes used for microbial enzymatic hydrolysis preferably include one or more of cellulase, hemicellulase, ligninase, β-glucosidase, xylanase, and protease. This invention does not have particular requirements for the cellulase, hemicellulase, ligninase, β-glucosidase, xylanase, and protease; commercially available enzyme products well-known to those skilled in the art can be used. In embodiments of this invention, the microbial enzymes are preferably cellulase, hemicellulase, and ligninase, and the preferred mass ratio of cellulase, hemicellulase, and ligninase is 3:1:1; the preferred mass ratio of the mixture obtained from the mixing of paper mulberry and straw raw materials to the microbial enzymes is 10:0.05. In this invention, the preferred temperature for microbial enzymatic hydrolysis is 50°C, and the preferred time is 10 hours.

[0040] In this invention, the specific operation of the microbial enzymatic hydrolysis preferably includes the following steps:

[0041] The microbial enzyme was dissolved in a citric acid-sodium citrate buffer solution to obtain an enzyme solution;

[0042] The mixture obtained by mixing paper mulberry and straw raw materials is added to the enzyme solution and mixed evenly, and then subjected to microbial enzymatic hydrolysis at 50°C.

[0043] In this invention, the concentration of the citric acid-sodium citrate buffer solution is preferably 0.1 mol / L, and the pH value is preferably 4.8; the ratio of the amount of microbial enzyme to the amount of citric acid-sodium citrate buffer solution is preferably 0.05 g: 30 mL.

[0044] In this invention, after microbial enzymatic hydrolysis, the obtained biomass material is preferably dried, pulverized, and sieved sequentially to obtain the bio-based nitrogen-doped carbon material precursor. In this invention, the drying temperature is preferably 110°C, and the drying time is preferably 12 hours; the sieving is preferably performed through a 120-200 mesh sieve.

[0045] This invention pretreats paper mulberry and straw raw materials through microbial enzymatic hydrolysis, thereby breaking down the dense and complex structure of paper mulberry and straw, making their structure loose and soft. At the same time, some paper mulberry proteins are degraded by enzymes to obtain polypeptides or amino acids. On the other hand, microbial enzymes, which are proteins composed of amino acids, and alkaloids in paper mulberry can both serve as nitrogen source precursors.

[0046] After obtaining the bio-based nitrogen-doped carbon material precursor, the present invention pyrolyzes and carbonizes the bio-based nitrogen-doped carbon material precursor in an inert atmosphere to obtain the nitrogen-doped carbon material. In the present invention, the inert atmosphere is preferably an argon atmosphere, the pyrolysis and carbonization temperature is preferably 400–800°C, more preferably 450–750°C, further preferably 550–650°C, and the time is preferably 1–24 h, more preferably 2–20 h, and further preferably 4–15 h. Preferably, the present invention places the bio-based nitrogen-doped carbon material precursor in a quartz boat, and places the quartz boat in a tube furnace for the pyrolysis and carbonization.

[0047] After obtaining the nitrogen-doped carbon material, the present invention reduces the nitrogen-doped carbon material by impregnating it in an aqueous nickel salt solution to obtain the supported nickel-based catalyst. In the present invention, the mass ratio of nickel salt to water in the aqueous nickel salt solution is preferably 1:10 to 1:20, and the nickel salt preferably includes one or more of nickel nitrate, nickel chloride, nickel sulfate, and nickel acetate; the mass ratio of nickel element to nitrogen-doped carbon material in the aqueous nickel salt solution is preferably 1:9 to 1:20, more preferably 1:10 to 1:15.

[0048] In this invention, nitrogen-doped carbon material is preferably added to the nickel salt aqueous solution, and after ultrasonication for 20 minutes, impregnation is performed. In this invention, the impregnation time is preferably 24–48 hours, more preferably 24–36 hours, and the impregnation can be performed at room temperature.

[0049] In this invention, after impregnation, the obtained impregnated material is preferably dried, pulverized, and sieved sequentially, followed by reduction. In this invention, the drying temperature is preferably 110–120°C, and the drying time is preferably 8–12 hours; the sieving is preferably through a 120–200 mesh sieve.

[0050] In this invention, the reduction is preferably carried out under a hydrogen atmosphere, the reduction temperature is preferably 400–800°C, more preferably 450–550°C, and the reduction time is preferably 3–6 hours, more preferably 4–5 hours. In this invention, the reduction is preferably carried out in a tube furnace. During the reduction process, nickel ions in the nickel salt undergo a reduction reaction under a hydrogen reducing atmosphere.

[0051] The process for preparing the supported nickel-based catalyst of the present invention is simple, the reaction conditions are mild, the raw materials are abundant and renewable, the metal in the catalyst is uniformly dispersed, the reaction activity is high, and it has good prospects for industrial application.

[0052] This invention provides the application of the supported nickel-based catalyst described in the above technical solutions, or the supported nickel-based catalyst prepared by the above preparation methods, in the catalytic separation of straw components, wherein the straw components include cellulose, hemicellulose, and lignin. This invention applies the supported nickel-based catalyst to the catalytic reduction separation of straw components, exhibiting high reactivity and good stability, and can efficiently achieve the catalytic separation and comprehensive utilization of straw components.

[0053] This invention provides a method for catalytic separation of straw components, comprising the following steps:

[0054] Straw, alcohol solvent, and catalyst are mixed in a hydrogen atmosphere and subjected to a catalytic reaction to obtain a reaction solution; the catalyst is the supported nickel-based catalyst described in the above technical solution or the supported nickel-based catalyst prepared by the preparation method described in the above technical solution;

[0055] The reaction mixture is subjected to solid-liquid separation to obtain liquid and solid products;

[0056] The solvent was removed from the liquid product to obtain lignin oil;

[0057] The solid product was sieved and separated to obtain holocellulose and the catalyst.

[0058] This invention involves mixing straw, an alcohol solvent, and a catalyst under a hydrogen atmosphere to conduct a catalytic reaction, yielding a reaction solution. In this invention, the straw particle size is preferably 20-40 mesh, more preferably 30 mesh; the straw is preferably dewaxed before use, and the dewaxing method is preferably to reflux extract the straw with water and ethanol in a Soxhlet extractor for 12 hours.

[0059] In this invention, the mass ratio of the catalyst to the straw is preferably 1:1 to 1:5. In this invention, the alcohol solvent preferably includes one or more of methanol, ethanol, propanol, and isopropanol, and the preferred ratio of straw to alcohol solvent is (0.1-1) g: (15-25) mL.

[0060] In this invention, the mixing of straw, alcohol solvent and catalyst is preferably ultrasonic mixing, the ultrasonic mixing time is preferably 20 min, and the ultrasonic mixing is preferably carried out in a quartz liner.

[0061] In this invention, the hydrogen pressure for the catalytic reaction is preferably 0.1–10 MPa, more preferably 2–5 MPa; the reaction temperature is preferably 200–240°C, more preferably 200–220°C; the heating rate from room temperature to the reaction temperature is preferably 5°C / min; and the reaction time is preferably 1–10 h, more preferably 5–8 h. In this invention, the catalytic reaction is preferably carried out under stirring conditions, and the stirring speed is preferably 300–600 rpm.

[0062] In this invention, the preferred specific operation of the catalytic reaction is as follows: a quartz liner containing a mixture of straw, alcohol solvent and catalyst is placed in a high-pressure reactor and sealed, and the reactor is purged with nitrogen and hydrogen five times respectively, and then hydrogen gas at 0.1-10 MPa is introduced to carry out the catalytic reaction.

[0063] During the catalytic reaction, lignin in the straw components is converted into lignin oil.

[0064] After the catalytic reaction is completed, it is preferable to stop stirring, immediately cool to room temperature with ice water to terminate the reaction, release the pressure, and open the vessel to obtain the reaction solution.

[0065] After obtaining the reaction solution, the present invention performs solid-liquid separation to obtain a liquid product and a solid product. In the present invention, the solid-liquid separation method is preferably vacuum filtration, the solid product includes cellulose, hemicellulose and the catalyst, and the liquid product includes phenolic compounds.

[0066] After obtaining the liquid and solid products, the present invention removes the solvent from the liquid product to obtain lignin oil; the solid product is then sieved to obtain holocellulose and the catalyst. In this invention, the solvent removal method is preferably rotary evaporation. Preferably, the solid product is repeatedly washed with methanol to obtain a filtrate and a solid filter residue; the filtrate and liquid product are combined, and the solid filter residue is subsequently dried and sieved to obtain holocellulose (cellulose and hemicellulose) and the catalyst. In this invention, the drying temperature is preferably 110°C, and the drying time is preferably 4 hours.

[0067] In this invention, the lignin oil comprises p-coumarate, ferulic acid ester, and ethyl guaiacol. In this invention, the holocellulose is preferably recycled as straw raw material for the preparation of the catalyst, i.e., the holocellulose is mixed with mulberry leaves and prepared using the aforementioned microbial enzymatic hydrolysis, pyrolysis carbonization, impregnation, and reduction methods to obtain a supported nickel-based catalyst, which is then reused for the catalytic separation of straw components.

[0068] This invention enables the effective separation of straw components and the comprehensive utilization of straw at high value. Using the method of this invention for catalytic separation of straw components, the yield of liquid product lignin oil is greater than 30%, and the recovery rate of solid product is greater than 85%.

[0069] To further illustrate the present invention, the supported nickel-based catalyst and its preparation method, as well as the catalytic separation method of straw components provided by the present invention, are described in detail below with reference to examples, but these should not be construed as limiting the scope of protection of the present invention.

[0070] Example 1

[0071] The preparation method of supported nickel-based catalysts is as follows:

[0072] Weigh 9g of 120-200 mesh hybrid mulberry leaf powder (crude protein content 18.9%) and 1g of 120-200 mesh corn stalk powder and mix them evenly. Dissolve 0.03g of cellulase, 0.01g of hemicellulase and 0.01g of ligninase in 30mL of 0.1mol / L citric acid-sodium citrate buffer solution with a pH of 4.8. Add the hybrid mulberry leaf powder and corn stalk powder to the enzyme solution and mix evenly. Enzymatically hydrolyze at 50℃ for 10 hours. Dry the sample at 110℃ for 12 hours to obtain the precursor sample, and pulverize it through a 120-200 mesh sieve.

[0073] The precursor sample was placed in a quartz boat and pyrolyzed in a tube furnace at 450°C under an argon atmosphere for 4 hours to carbonize it, yielding 4.2g of nitrogen-doped carbon material, denoted as CN-450.

[0074] 1 g of nickel nitrate hexahydrate was dissolved in 10 mL of water. 2 g of nitrogen-doped carbon material was added and ultrasonically mixed for 20 minutes. The mixture was then impregnated for 24 hours, dried at 110 °C for 12 hours, and pulverized through a 120–200 mesh sieve to obtain a nitrogen-doped carbon-supported nickel-based catalyst. Before use, the catalyst was reduced at 450 °C for 4 hours in a tube furnace under a hydrogen atmosphere to obtain the activated nickel-based catalyst Ni / CN-450.

[0075] The catalytic separation of straw components is performed as follows:

[0076] Weigh 0.1g of 30-mesh dewaxed corn stalks, 0.1g of Ni / CN-450 catalyst, and 15mL of methanol. Add these to a 50mL quartz-lined container and sonicate for 20 minutes until homogeneous. Place the mixture in a high-pressure reactor and seal it. Purge the reactor five times with nitrogen and five times with hydrogen. Then, purge with 2MPa hydrogen gas, stir at 600rpm, and heat to 200℃ at 5℃ / min for 5 hours. Immediately after the reaction is complete, cool to room temperature with ice water to terminate the reaction. Release the pressure and open the reactor. Filter the reactants for solid-liquid separation, obtaining the liquid product lignin oil and a solid residue containing cellulose, hemicellulose, and the catalyst. Wash the solid residue repeatedly with methanol, collect the filtrate, and combine the liquid product and the filtrate. Dry the solid filter residue at 110℃ for 4 hours, then sieve to separate the solid product and the catalyst. Weigh the solid products (cellulose and hemicellulose) to calculate the solid product recovery rate (relative to the initial mass of cellulose and hemicellulose in the straw). The combined liquid products were subjected to rotary evaporation to remove the solvent, yielding lignin oil. The lignin oil yield (relative to the initial mass of straw) was calculated by weighing. The results are shown in Table 1.

[0077] The lignin oil was dissolved in 5 mL of methanol and then qualitatively analyzed by GC-MS. The results are shown in the figure. Figure 2 The main components of lignin oil include 4-ethyl-2-methoxyphenol, 4-allyl-2,6-dimethoxyphenol, methyl 4-hydroxycinnamate, and methyl ferulic acid.

[0078] Examples 2-4

[0079] The precursor samples were pyrolyzed at temperatures of 550℃, 650℃, and 750℃, respectively, with the remaining steps being the same as in Example 1. Ni / CN-550, Ni / CN-650, and Ni / CN-750 were obtained, respectively.

[0080] Ni / CN-550, Ni / CN-650, and Ni / CN-750 were used in the catalytic separation reaction of straw components. The methods and conditions were the same as in Example 1, and the results are shown in Table 1.

[0081] Examples 5-6

[0082] The weights of hybrid mulberry leaf powder and corn stalk powder were 8g and 2g, and 7g and 3g, respectively, and the remaining steps were the same as in Example 1. Ni / CN1-450 and Ni / CN2-450 were prepared respectively.

[0083] Ni / CN1-450 and Ni / CN2-450 catalysts were applied to the catalytic separation reaction of straw components. The methods and conditions were the same as in Example 1, and the results are shown in Table 1.

[0084] Examples 7-9

[0085] The solid products obtained in Examples 1, 5, and 6 were mixed evenly with 9 grams of hybrid mulberry leaf powder and subjected to enzymatic hydrolysis and pyrolysis carbonization to prepare carbon nitride precursors. The remaining steps were the same as in Example 1. The catalysts prepared were designated as Ni / CN11-450, Ni / CN51-450, and Ni / CN61-450, respectively.

[0086] Ni / CN11-450, Ni / CN51-450, and Ni / CN61-450 were used in the catalytic separation reaction of straw components. The method and conditions were the same as in Example 1, and the results are shown in Table 1.

[0087] Comparative Example 1

[0088] A nickel-based catalyst, denoted as Ni / C-450, was prepared by replacing the 2g nitrogen-doped carbon material in Example 1 with 2g activated carbon as a support and using the impregnation-supported reduction method of Example 1. The Ni / C-450 catalyst was applied to the catalytic separation reaction of straw components, and the method and conditions were the same as in Example 1. The results are shown in Table 1.

[0089] Table 1. Results of straw component separation catalyzed by different nickel-based catalysts in the examples and comparative examples.

[0090] Example catalyst Ligno oil yield % Solid product recovery rate % Example 1 Ni / CN-450 35.6 95.2 Example 2 Ni / CN-550 33.8 93.8 Example 3 Ni / CN-650 32.7 92.6 Example 4 Ni / CN-750 31.3 90.7 Example 5 Ni / CN1-450 34.6 88.6 Example 6 Ni / CN2-450 33.4 89.3 Example 7 Ni / CN11-450 35.3 95.3 Example 8 Ni / CN51-450 35.4 94.9 Example 9 Ni / CN61-450 35.2 94.7 Comparative Example 1 Ni / C-450 26.6 80.5

[0091] As can be seen from the above embodiments, the present invention can achieve effective separation of straw components and realize the comprehensive utilization of straw with high value. After catalytic separation, the straw components yield liquid lignin oil with a yield of more than 30% and solid product recovery rate of more than 85%.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A supported nickel-based catalyst, characterized in that, The invention includes a bio-based nitrogen-doped carbon carrier and an active metallic nickel loaded on the bio-based nitrogen-doped carbon carrier. The bio-based nitrogen-doped carbon carrier is obtained by pyrolysis and carbonization of the product of microbial enzymatic fermentation of a mixture of straw and paper mulberry as a biomass nitrogen-containing precursor, or by pyrolysis and carbonization of the product of microbial enzymatic fermentation of a mixture of holocellulose obtained from straw and paper mulberry as a biomass nitrogen-containing precursor, or by pyrolysis and carbonization of straw and the product of microbial enzymatic fermentation of a mixture of holocellulose obtained from straw and paper mulberry as a biomass nitrogen-containing precursor.

2. The method for preparing the supported nickel-based catalyst according to claim 1, characterized in that, Includes the following steps: Microbial enzymatic hydrolysis is performed by mixing straw with paper mulberry, or microbial enzymatic hydrolysis is performed by mixing holocellulose obtained from straw with paper mulberry, or microbial enzymatic hydrolysis is performed by mixing straw, holocellulose obtained from straw with paper mulberry, to obtain a bio-based nitrogen-doped carbon material precursor. The bio-based nitrogen-doped carbon material precursor was pyrolyzed and carbonized in an inert atmosphere to obtain the nitrogen-doped carbon material. The nitrogen-doped carbon material was impregnated in an aqueous nickel salt solution and then reduced to obtain the supported nickel-based catalyst.

3. The preparation method according to claim 2, characterized in that, The paper mulberry, straw, and holocellulose separated from the straw are powders with an independent particle size of 120-200 mesh. The mass ratio of straw to paper mulberry is 1:99-1:2, the mass ratio of holocellulose separated from straw to paper mulberry is 1:99-1:2, and the ratio of the total mass of straw and holocellulose separated from straw to the mass of paper mulberry is 1:99-1:

2.

4. The preparation method according to claim 2, characterized in that, The pyrolysis carbonization temperature is 400~800℃, and the time is 1~24h.

5. The preparation method according to claim 2, characterized in that, The mass ratio of nickel salt to water in the nickel salt aqueous solution is 1:10 to 1:20, and the nickel salt includes one or more of nickel nitrate, nickel chloride, nickel sulfate, and nickel acetate; the mass ratio of nickel element to nitrogen-doped carbon material in the nickel salt aqueous solution is 1:9 to 1:

20.

6. The preparation method according to claim 2 or 5, characterized in that, The impregnation time is 24~48h; the reduction is carried out in a hydrogen atmosphere at a temperature of 400~800℃ for 3~6h.

7. The application of the supported nickel-based catalyst of claim 1 or the supported nickel-based catalyst prepared by any one of claims 2 to 6 in the catalytic separation of straw components, wherein the straw components include cellulose, hemicellulose and lignin.

8. A method for catalytic separation of straw components, characterized in that, Includes the following steps: Straw, alcohol solvent, and catalyst are mixed in a hydrogen atmosphere and subjected to a catalytic reaction to obtain a reaction solution; the catalyst is the supported nickel-based catalyst of claim 1 or the supported nickel-based catalyst prepared by any one of claims 2 to 6; The reaction mixture is subjected to solid-liquid separation to obtain liquid and solid products; The solvent was removed from the liquid product to obtain lignin oil; The solid product was sieved and separated to obtain holocellulose and the catalyst.

9. The method according to claim 8, characterized in that, The mass ratio of the catalyst to the straw is 1:1 to 1:5; the alcohol solvent includes one or more of methanol, ethanol, propanol and isopropanol, and the ratio of straw to alcohol solvent is (0.1~1)g:(15~25)mL.

10. The method according to claim 8 or 9, characterized in that, The hydrogen pressure for the catalytic reaction is 0.1~10MPa, the reaction temperature is 200~240℃, and the reaction time is 1~10h.

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