Catalyst for preparing cyclohexane through hydrodepolymerization of lignin as well as preparation method and application of catalyst
The kaolin support nickel-ruthenium catalyst is used to hydrolyze lignin in anhydrous ethanol solvent, and the problem of many preparation steps and high energy consumption in the prior art is solved, and the conversion of high efficiency and green lignin to cyclohexane is achieved. , the yield reaches more than 20%, and it has broad industrial application prospects.
Patent Information
- Application Number
- CN202411382890.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-01-07
AI Technical Summary
In the prior art, the method of preparing cyclohexane using lignin as raw material has many steps and high energy consumption, and lacks efficient, green and economical technical methods.
Using kaolin as a support, nickel and ruthenium as catalysts for active components, cyclohexane is prepared by hydrolyzing and depolymerizing lignin in anhydrous ethanol solvents, using the unique electronic structure of nickel and the hydrodeoxygenation function of ruthenium. The Ni-O-Ru interface and the NiRu alloy active site are formed to promote the depolymerization and hydrogenation of lignin.
100% conversion of lignin, the yield of cyclohexane monomer is greater than 20%, and the catalyst preparation and reaction process are highly efficient, green and economical, and are suitable for industrial applications.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of catalysts, and in particular to a catalyst for preparing cyclohexane by hydrogenating and depolymerizing lignin, and a preparation method and application thereof. Background Art
[0002] Biomass is a renewable carbon-neutral resource that can be used to prepare liquid fuels and chemicals. Among them, wood cellulose is composed of cellulose, hemicellulose and lignin. Compared with cellulose and hemicellulose, there are fewer mature industrial utilization technologies for lignin. The efficient conversion of lignin has become the key to the comprehensive utilization of biomass. Lignin is a three-dimensional network macromolecule composed of a large number of aromatic rings cross-linked by CC and COC bonds. It is a natural aromatic polymer with abundant reserves in nature.
[0003] Cyclohexane is a cycloalkane, similar to hexane, a non-polar solvent, insoluble in water. Cyclohexane is an important solvent, often used to dissolve fats, oils, waxes, lacquers, resins and cellulose ethers. Cyclohexane is also an important platform molecule for chemical production, often used in the production of adipic acid in industries such as perfume, nylon 66, paints and varnishes.
[0004] At present, the method for preparing cyclohexane using lignin as raw material is mainly to convert lignin into phenol, and then hydrodeoxygenate phenol to prepare cyclohexane. This technology has many steps and high energy consumption. Therefore, it is urgent to develop an efficient, green and economical technical method for preparing cyclohexane from lignin. Summary of the invention
[0005] The main purpose of the present invention is to provide a catalyst capable of efficiently converting lignin into cyclohexane by hydrogenation and depolymerization, and a preparation method and application thereof.
[0006] To achieve the above object, the present invention provides a catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin, comprising a carrier and active components supported on the carrier, wherein the carrier is kaolin and the active components are nickel and ruthenium.
[0007] Furthermore, the nickel content is 10-30wt%, the ruthenium content is 5-10wt%, and the balance is kaolin.
[0008] The present invention also provides a method for preparing the above-mentioned catalyst for preparing cyclohexane by hydrogenating and depolymerizing lignin, comprising the following steps: dissolving precursor salts of nickel and ruthenium in deionized water, adding a citric acid solution, then heating and stirring until a gel is formed, then adding kaolin, and then heating and stirring until all the water evaporates, then drying the remaining solid, then grinding it into powder, and finally calcining it under a nitrogen atmosphere, and then cooling it to room temperature to obtain the catalyst for preparing cyclohexane by hydrogenating and depolymerizing lignin.
[0009] Furthermore, the amount of citric acid solution added is such that the molar ratio of metal ions to citric acid reaches 1:1.5, and the temperature condition for the heating and stirring treatment is 85°C.
[0010] Furthermore, the drying conditions are a temperature of 105° C. and a time of 12 h.
[0011] Furthermore, the specific process of the calcination treatment is: heating to 650°C at a heating rate of 2°C / min, and then calcining at this temperature for 4 hours.
[0012] The present invention also provides an activation method for the above-mentioned catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin, characterized in that it includes the following steps: reducing and activating the catalyst in a 100 mL / min 10% H2 / 90% N2 gas flow and a temperature of 650°C for 4 hours.
[0013] The present invention also provides the use of the above catalyst in catalyzing the hydrogenation and depolymerization of lignin to prepare cyclohexane under the condition of ethanol as solvent and only initial hydrogen atmosphere.
[0014] Catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin A method for preparing cyclohexane by catalytic hydrogenation and depolymerization of lignin includes the following steps: putting lignin, ethanol and the above catalyst into a reactor, filling it with hydrogen and then conducting a sealed reaction.
[0015] Furthermore, the amount of hydrogen charged is 1-3 MPa, the mass ratio of lignin, catalyst and ethanol is 1:0.01-0.1:40-60, and the reaction conditions are temperature 290-350°C, stirring rate 500 r / min, and time 12-48 h.
[0016] The catalyst of the present invention uses kaolin as a carrier and a mixture of nickel and ruthenium as an active component, which can enhance the ability of the catalyst to crack lignin; the kaolin has a well-developed internal void structure, a large surface area and a strong adsorption capacity, can fully disperse the catalytic active components and adsorb reactant molecules, and has abundant acid sites on the surface, which can effectively realize the breaking of the lignin ether bond; the nickel metal and its oxide have a unique electronic structure, show excellent CO and CC bond selective breaking ability in the lignin depolymerization process, and can activate hydrogen molecules, promote ethanol dehydrogenation and provide an in-situ hydrogen source; ruthenium, as a classic catalyst with hydrogenation and deoxygenation function, can fully activate molecular hydrogen and ethanol solvent and CH / OH bonds of lignin, generate an in-situ hydrogen source and combine with the lignin depolymerization reactive intermediate, and reduce coking in the reaction process; the nickel and ruthenium in the catalyst can form a Ni-O-Ru interface and the NiRu alloy active site can promote the adsorption of phenol intermediates containing benzene rings, thereby promoting the hydrogenation of benzene rings to form cyclohexane.
[0017] The beneficial effects of the present invention are embodied in:
[0018] The catalyst of the present invention can be applied to catalytic hydrogenation depolymerization of lignin to prepare cyclohexane. In an anhydrous ethanol solvent, only an initial hydrogen atmosphere is required to achieve 100% conversion of lignin, and the cyclohexane monomer yield is greater than 20%, completing the one-step conversion of lignin to hydrocarbon fuels. The catalyst preparation and reaction process are characterized by high efficiency, greenness, economy and renewability, and have broad prospects for industrial application. DETAILED DESCRIPTION
[0019] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.
[0020] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or can be obtained by existing known methods; unless otherwise specified, the methods used in the embodiments of the present invention are methods known to those skilled in the art. Among them, lignin was purchased from Sinopharm Chemical Reagent Co., Ltd. (brand ALDRICH, CAS No. 8068-05-1); kaolin was purchased from Sinopharm Chemical Reagent Co., Ltd. (brand Shanghai Test; CAS No. 1332-58-7).
[0021] Example 1
[0022] Preparation of catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin
[0023] The specific preparation method is as follows:
[0024] 1.7493g Ni(NO3)2·6H2O, 0.5538g Ru(NO)(NO3)3 is added to 30mL of deionized water and stirred thoroughly to dissolve to form a uniform solution, and then 115.5mL of 0.1mol / L citric acid solution is added, and then stirred at 80°C and 150r / min until a gel is formed, and then 3.0000 kaolin is added to the above gel, and stirred continuously at 85°C and 150r / min until all the water evaporates, and then the evaporated solid is dried at 105°C for 12h, and then ground into solid powder; the solid powder is placed in a tubular furnace, and the temperature is increased from room temperature to 650°C at a heating rate of 2°C / min under a nitrogen atmosphere, and then calcined at 650°C for 4h and naturally cooled to room temperature, so that the catalyst with a nickel content of 10wt% and a ruthenium content of 5wt% for preparing cyclohexane by hydrogenation and depolymerization of lignin can be obtained, which is recorded as 10Ni5Ru / KL.
[0025] Example 2
[0026] Preparation of catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin
[0027] The specific preparation method is as follows:
[0028] 7.4315g Ni(NO3)2·6H2O, 1.5698g Ru(NO)(NO3)3 is added to 30mL of deionized water and stirred thoroughly to dissolve to form a uniform solution, and then 153mL of 0.3mol / L citric acid solution is added, and then stirred at 80°C and 150r / min until a gel is formed, and then 3.0000 kaolin is added to the above gel, and stirred continuously at 85°C and 150r / min until all the water evaporates, and then the evaporated solid is dried at 105°C for 12h, and then ground into solid powder; the solid powder is placed in a tubular furnace, and the temperature is increased from room temperature to 650°C at a heating rate of 2°C / min under a nitrogen atmosphere, and then calcined at 650°C for 4h and naturally cooled to room temperature, so that the catalyst with a nickel content of 30wt% and a ruthenium content of 10wt% for preparing cyclohexane by hydrogenation and depolymerization of lignin can be obtained, which is recorded as 30Ni10Ru / KL.
[0029] Example 3
[0030] Preparation of catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin
[0031] The specific preparation method is as follows:
[0032] 4.1302g Ni(NO3)2·6H2O and 1.0457g Ru(NO)(NO3)3 were added to 30mL deionized water and stirred to dissolve to form a uniform solution. Then 87.5mL 0.3mol / L citric acid solution was added, and then stirred at 80°C and 150r / min until a gel was formed. Then 3.0000 kaolin was added to the gel, and the mixture was stirred at 85°C and 150r / min until all the water evaporated. The remaining solid was then dried at 105°C for 12h and ground into solid powder. The solid powder was placed in a tubular furnace, and heated from room temperature to 650°C at a heating rate of 2°C / min under a nitrogen atmosphere, and then calcined at 650°C for 4h, and finally naturally cooled to room temperature to obtain a catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin with a nickel content of 20wt% and a ruthenium content of 8wt%, which was recorded as 20Ni8Ru / KL.
[0033] Example 4
[0034] Preparation of catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin
[0035] The specific preparation method is as follows:
[0036] Combine 5.7201g Ni(NO3)2·6H2O, 1.4486g Ru(NO)(NO3)3 is added to 30mL of deionized water and stirred thoroughly to dissolve to form a uniform solution, and then 121.5mL of 0.3mol / L citric acid solution is added, and then stirred at 80°C and 150r / min until a gel is formed, and then 3.0000 kaolin is added to the above gel, and stirred continuously at 85°C and 150r / min until all the water evaporates, and then the evaporated solid is dried at 105°C for 12h, and then ground into a solid powder; the solid powder is placed in a tubular furnace, and the temperature is increased from room temperature to 650°C at a heating rate of 2°C / min under a nitrogen atmosphere, and then calcined at a constant temperature of 650°C for 4h, and finally naturally cooled to room temperature, so as to obtain a catalyst with a nickel content of 25wt% and a ruthenium content of 10wt% for preparing cyclohexane by hydrogenation and depolymerization of lignin, which is recorded as 25Ni10Ru / KL.
[0037] Example 5
[0038] Preparation of catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin
[0039] The specific preparation method is as follows:
[0040] 2.8592g Ni(NO3)2·6H2O and 0.8444g Ru(NO)(NO3)3 were added to 30mL deionized water and stirred to dissolve to form a uniform solution. Then 125mL 0.15mol / L citric acid solution was added, and then stirred at 80°C and 150r / min until a gel was formed. Then 3.0000 kaolin was added to the gel, and stirred at 85°C and 150r / min until all the water evaporated. The evaporated solid was then dried at 105°C for 12h and ground into solid powder. The solid powder was placed in a tubular furnace, and heated from room temperature to 650°C at a heating rate of 2°C / min under a nitrogen atmosphere, and then calcined at 650°C for 4h, and finally naturally cooled to room temperature to obtain a catalyst with a nickel content of 15wt% and a ruthenium content of 7wt% for preparing cyclohexane by hydrogenation and depolymerization of lignin, which was recorded as 15Ni7Ru / KL.
[0041] Example 6
[0042] Preparation of catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin
[0043] The specific preparation method is as follows:
[0044] 3.6651g Ni(NO3)2·6H2O and 1.1600g Ru(NO)(NO3)3 were added to 30mL deionized water and stirred to dissolve to form a uniform solution. Then 81.5mL 0.3mol / L citric acid solution was added, and then stirred at 80°C and 150r / min until a gel was formed. Then 3.0000g kaolin was added to the gel, and the mixture was stirred at 85°C and 150r / min until all the water evaporated. The remaining solid was then dried at 105°C for 12h and ground into solid powder. The solid powder was placed in a tubular furnace, and the temperature was increased from room temperature to 650°C at a heating rate of 2°C / min under a nitrogen atmosphere, and then calcined at 650°C for 4h, and finally naturally cooled to room temperature to obtain a catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin with a nickel content of 18wt% and a ruthenium content of 9wt%, which was recorded as 18Ni9Ru / KL.
[0045] Comparative Example 1
[0046] In this comparative example, the catalyst was prepared according to the same method as in Example 3, with the only difference being that the addition of Ni(NO3)2·6H2O was omitted, the amount of Ru(NO)(NO3)3 was adjusted to 0.8186 g, and the amount of citric acid solution was adjusted to 78 mL of 0.05 mol / L citric acid solution, ultimately obtaining a kaolin-loaded ruthenium catalyst with a ruthenium content of 8 wt%, recorded as 8Ru / KL.
[0047] Comparative Example 2
[0048] In this comparative example, the catalyst was prepared according to the same method as in Example 3, with the only difference being that the addition of Ru(NO)(NO3)3 was omitted, and the amount of Ni(NO3)2·6H2O was adjusted to 3.7166 g, and the amount of citric acid solution was adjusted to 96 mL of 0.2 mol / L citric acid solution, ultimately obtaining a kaolin-loaded nickel catalyst with a nickel content of 20 wt%, recorded as 20Ni / KL.
[0049] Comparative Example 3
[0050] In this comparative example, the catalyst is prepared according to the method of Example 3, with the only difference being that Co(NO3)2·6H2O is used instead of Ni(NO3)2·6H2O, and the amount of the precursor salt of each active component is adjusted to 4.1150g Co(NO3)2·6H2O and 1.0460g Ru(NO)(NO3)3, and the amount of citric acid solution is adjusted to 130.5mL of 0.2mol / L citric acid solution, and finally a kaolin-loaded cobalt-ruthenium catalyst with a cobalt content of 20wt% and a ruthenium content of 8wt% is obtained, which is recorded as 20Co8Ru / KL.
[0051] Performance test of kaolin supported nickel-ruthenium catalyst for catalytic hydrogenation depolymerization of lignin to produce cyclohexane
[0052] Test method: The catalyst was reduced and activated at 650°C for 4h in a 100mL / min 10% H2 / 90% N2 gas flow. Then 1g lignin, 0.01-0.1g reduced and activated catalyst, and 40-60g ethanol were weighed and added to a high-pressure reactor, filled with 1-3MPa initial hydrogen pressure, and then sealed and reacted at 290-350°C and a stirring rate of 500r / min for 12-48h, and then the reaction product was filtered to obtain a liquid product, and then an extractant composed of acetone and ethyl acetate (mixed in a volume ratio of 1:1) was added to the liquid product for extraction, and then the extractant layer was taken out, and the extractant layer was subjected to rotary evaporation at 55°C to remove the extractant, and finally the rotary evaporation product was quantitatively analyzed.
[0053] The specific reaction conditions and results are shown in Table 1.
[0054] Table 1
[0055]
[0056]
[0057] From the above results, it can be concluded that the catalyst of the present invention can achieve full conversion of lignin in anhydrous ethanol solvent system by only providing an initial hydrogen source, achieving a 100% lignin conversion rate and a cyclohexane yield of more than 20%. The lignin conversion rate of the comparative example is less than 90%, and the cyclohexane yield is less than 10%.
[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin, characterized in that: The invention comprises a carrier and active components loaded on the carrier, wherein the carrier is kaolin, and the active components are nickel and ruthenium.
2. The catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin according to claim 1, characterized in that: The nickel content is 10-30wt%, the ruthenium content is 5-10wt%, and the balance is kaolin.
3. The method for preparing a catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin according to claim 1 or 2, characterized in that: The method comprises the following steps: dissolving nickel and ruthenium precursor salts in deionized water, adding citric acid solution, heating and stirring until a gel is formed, adding kaolin, heating and stirring until all water evaporates, drying the remaining solid, grinding it into powder, and finally calcining it under a nitrogen atmosphere, and then cooling it to room temperature to obtain the catalyst for preparing cyclohexane by hydrogenating and depolymerizing lignin.
4. The method for preparing a catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin as claimed in claim 3, characterized in that: The amount of citric acid solution added was such that the molar ratio of metal ions to citric acid reached 1:1.5, and the temperature condition for the heating and stirring treatment was 85°C.
5. The method for preparing a catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin as claimed in claim 3, characterized in that: The drying conditions were 105°C and 12 h.
6. The method for preparing a catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin as claimed in claim 3, characterized in that: The specific process of the calcination treatment is: heating the temperature to 650°C at a heating rate of 2°C / min, and then calcining at this temperature for 4 hours.
7. The method for activating the catalyst for preparing cyclohexane by hydrogenation and depolymerization of lignin according to claim 1 or 2, characterized in that: The method comprises the following steps: reducing and activating the catalyst under a 100 mL / min 10% H2 / 90% N2 gas flow and a temperature of 650° C. for 4 hours.
8. Use of the catalyst as claimed in claim 1 or 2 in catalyzing the hydrogenation and depolymerization of lignin to prepare cyclohexane under the conditions of ethanol as solvent and only initial hydrogen atmosphere.
9. A method for preparing cyclohexane by catalytic hydrogenation and depolymerization of lignin, characterized in that: The method comprises the following steps: putting lignin, ethanol and the catalyst as claimed in claim 1 or 2 into a reactor, filling with hydrogen and then conducting a sealed reaction.
10. The method for preparing cyclohexane by catalytic hydrogenation and depolymerization of lignin as claimed in claim 9, characterized in that: The amount of hydrogen charged is 1-3 MPa, the mass ratio of lignin, catalyst and ethanol is 1:0.01-0.1:40-60, and the reaction conditions are temperature 290-350°C, stirring speed 500 r / min and time 12-48 h.