Method for preparing cyclohexanol through phenol aqueous phase hydrogenation and catalyst thereof

Abstract

The invention relates to an efficient catalysis method for preparing cyclohexanol through phenol selective hydrogenation reaction and a catalyst thereof, in particular to a method for preparing cyclohexanol through phenol water phase hydrogenation catalyzed by lignin carbon anchored Ni nanoparticles based on a Ni-BDC MOF template, and belongs to the technical field of fine chemical preparation. A Ni-based MOF material Ni-BDC is used as a structure-directing agent and a nickel source, an industrial byproduct enzymatic hydrolysis lignin is used as a carbon source, dispersion, anchoring and reduction of metal nickel are realized through two-stage treatment of a one-pot solvothermal method and pyrolysis carbonization, and the lignin-based carbon anchoring Ni nanoparticle catalyst with good dispersion is obtained. The method can realize high conversion rate and high selectivity directional conversion from phenol to cyclohexanol under a water phase mild condition, has good catalyst recycling performance, and can be used as a novel biomass high-valued environment-friendly method for taking lignin and using lignin.

Description

Technical Field

[0001] The present invention relates to an efficient catalytic method for preparing cyclohexanol by hydrogenation of phenol and its catalyst, specifically a method for preparing cyclohexanol by catalytic hydrogenation of phenol in aqueous phase using Ni nanoparticles anchored on lignin carbon based on a Ni-BDC MOF template, belonging to the technical field of fine chemical preparation. Background Art

[0002] As a biomass resource rich in nature and the only one containing aromatic rings, lignin has far from been fully utilized. Most of it is discarded or used as low-grade fuels, concrete additives, etc., causing environmental pollution and waste of resources. At present, the high-value utilization directions of lignin and its derivatives mainly include: producing high-value-added chemicals, alternative fuels and platform compounds through processes such as depolymerization; being used as the main component of renewable materials through chemical modification; using the stable aromatic ring skeleton and rich functional groups in its structure to process into functional group donors or carbon-based carriers in catalysts. Among them, phenol is one of the main components of lignin depolymerization bio-oil, and its hydrogenation reaction is a model reaction in the lignin upgrading process, which is of great significance for the efficient conversion of biomass resources into value-added chemicals. Its hydrogenation product cyclohexanol is an important chemical intermediate and is widely used in the production of caprolactam for nylon-6 and adipic acid for nylon-66 [Fuel, 2023, 334: 126577; Cata. Sci. Technol., 2021, 11, 1881-1887]. Therefore, the operating cost and efficiency of the phenol catalytic hydrogenation process are the key to its large-scale application.

[0003] Noble metal Ru-based catalysts have been found to have excellent activity in the hydrogenation reaction of phenol. Ru / Nb2O5-nC 18In a two-phase solvent system composed of water and decalin, PA catalyzes the conversion of phenol close to 100% within 4 hours at 80 °C and 12 bar H2, and the yield of cyclohexanol reaches 93% [Green Chemistry, 2022, 24(3): 1152-1164]; Ru@N-CS supported on N-doped mesoporous hollow carbon spheres can react for 30 min at 80 °C and 0.5 MPa H2 in an aqueous medium to achieve a 100% yield of cyclohexanol [Catalysts, 2022, 12: 995]; Ru-RuO2-Nb2O5 / Hβ can basically convert phenol into cyclohexanol with a yield of 98.2% under the conditions of 30 °C, 2 MPa H2, and 9 h [Chemical Engineering Journal, 2023, 453: 139718]. Using non-noble metal-based catalysts requires higher reaction conditions. 10 wt% Ni / AC supported on activated carbon for the hydrogenation of phenol in aqueous phase requires a hydrogen-argon mixture (volume ratio 1:4) of 1.5 MPa, 180 °C, and 2 h, and the conversion rate and cyclohexanol selectivity reach 99.7% and 94.8% respectively [Carbon, 2023, 213: 118227]; NiCo / Ti-Si reacts at 1 MPa H2 and 100 °C for 1 h, with a conversion rate of 98.2% and a cyclohexanol selectivity of 99% [Applied Catalysis A: General, 2020, 591: 117409]; NiCo(1 / 2)@C-600 prepared from NiCo(x / y)-MOF-74 as raw material can achieve 100% conversion of phenol to cyclohexanol at 120 °C, 1.5 MPa H2, and 2 h [Reaction Chemistry & Engineering, 2022, 7(2): 429-441]. The Ni@CN-450 particles prepared by directly pyrolyzing Ni-MOF-74(N) as raw material have better dispersion. In the catalytic transfer hydrogenation reaction of phenol with isopropanol as the hydrogen donor, the phenol conversion rate is 99.3% and the cyclohexanol selectivity is 100% under the conditions of 180 °C, 1 MPa, and 0.5 h [New Journal of Chemistry, 2022, 46(35): 16941-16950].

[0004] The above background technology shows that Ni-based catalysts have a strong adsorption and activation ability for H2 due to their suitable atomic volume, wider d-electron bands, and higher lattice plane density, and can provide more active hydrogen species for hydrogenation reactions. They are an ideal choice for non-noble metal catalysts for the selective hydrogenation of phenol [Carbon, 2023, 213: 118227]. The dispersion of metallic Ni is a key factor affecting its activity, cost, and reaction conditions. Metal-organic frameworks (MOFs) have been found to be able to anchor active metal centers on the derivatized framework by utilizing the strong coordination between metals and organic ligands and the confinement effect of their network structure. After treatments such as thermal annealing, the pore environment and the required structure can be almost completely retained, thus effectively preventing the aggregation and growth of metal particles and obtaining highly dispersed and stable active metal centers for the catalyst [Journal of Materials Chemistry: A, 2023, 11: 23809-23820; Industrial Crops and Products, 2024, 216: 118727; Reaction Chemistry & Engineering, 2022, 7: 170-180; Green Chemistry, 2024, 26: 4544-4551; Energy Fuels, 2023, 37: 3825-3835]. Lignin and its derivatives containing a large number of oxygen-containing functional groups in the structure also have a coordination ability with metals and are often used as natural precursors for constructing hierarchically porous carbon materials for highly dispersed metal catalysts. Therefore, using non-noble metal-based MOFs as sacrificial templates and structure-directing agents and lignin derivatives as renewable carbon sources to construct highly efficient metal catalysts can provide a novel strategy for the hydrogenation upgrading of biomass-based raw materials such as lignin platform compounds [Chemical Engineering Journal, 2023, 473: 145375].

[0005] So far, there have been no reports at home and abroad on the preparation of Ni-based nanoparticle catalysts using Ni-BDC MOF as a structure-directing agent and nickel source and enzymatic lignin from industrial waste as a renewable carbon source by a one-pot solvothermal method and a pyrolytic carbon reduction method for the efficient preparation of cyclohexanol by the aqueous-phase hydrogenation of phenol. Summary of the Invention

[0006] The present invention uses easily prepared Ni-BDC MOF as a structure-directing agent and nickel source, combines inexpensive and readily available enzymatic lignin as a biomass carbon source, obtains a catalyst precursor by a one-pot solvothermal method, and then prepares a novel lignin-carbon-anchored metallic Ni nanoparticle catalyst Ni@BDC-ELC through pyrolytic carbonization and reduction, and catalytically hydrogenates phenol in the aqueous phase under mild conditions to highly selectively prepare cyclohexanol.

[0007] The technical solution of the present invention is as follows:

[0008] In a reaction kettle, phenol as the raw material and water as the solvent were added respectively at a ratio of 8 mL of solvent per mmol of raw material. Under stirring conditions, the prepared catalyst was added at a ratio of 10 - 20 mg of catalyst per mmol of raw material. The air was replaced with hydrogen 4 - 5 times, and 0.5 - 1.5 MPa of H2 was charged. The reaction was carried out at 80 - 120 °C for 2 - 6 h. After the reaction, the product was extracted with ethyl acetate and the catalyst was separated by centrifugation. After drying the organic phase, it was quantitatively analyzed by gas chromatography.

[0009] The catalyst described in the above technical solution is Ni@BDC - ELC, which is lignin - carbon - anchored Ni nanoparticles based on the Ni - BDC MOF template. Its preparation method is as follows:

[0010] Nickel nitrate hexahydrate was dissolved in N,N - dimethylformamide to form solution A at a ratio of 10.8 mmol of nickel salt per 30 mL of solvent. Terephthalic acid and enzymatically hydrolyzed lignin were dissolved in N,N - dimethylformamide to form solution B at a ratio of 5.4 mmol of terephthalic acid and 0.2 g of enzymatically hydrolyzed lignin per 30 mL of solvent. Solution A and solution B were rapidly mixed and transferred to a Teflon - lined stainless - steel autoclave, and the reaction was carried out at 120 °C for 24 h. After the reaction, the solid was separated by filtration and washed with ethanol 3 times, dried in vacuum at 80 °C for 12 h, and calcined in a tube furnace at 500 °C for 2 h in an N2 atmosphere to obtain the catalyst Ni@BDC - ELC, which is lignin - carbon - anchored metal Ni nanoparticles based on the Ni - BDC MOF template.

[0011] The method for preparing cyclohexanol by catalytic hydrogenation of phenol in aqueous phase using Ni@BDC - ELC, which is lignin - carbon - anchored Ni nanoparticles based on the Ni - BDC MOF template provided by the present invention, has the following advantages compared with the prior art:

[0012] (1) The present invention provides a method that uses Ni - based MOF as a structure - guiding agent and nickel source, and industrial by - product enzymatically hydrolyzed lignin as a carbon source, combines the one - pot solvothermal method and the pyrolysis carbonization reduction process to realize the dispersion, anchoring, and reduction of metallic nickel, and provides an efficient catalyst for phenol hydrogenation.

[0013] (2) In the method provided by the present invention, the lignin - based carbon - anchored Ni 0 catalytic material based on the Ni - BDC MOF template has good dispersion, and its activity is close to that of noble - metal - based catalysts. It can realize the efficient and directional conversion of phenol to cyclohexanol under mild conditions in the aqueous phase, and the catalyst has good recyclability, which can be used as a new method for the high - value utilization of biomass of "derived from lignin and used for lignin". Description of the Drawings

[0014] Appendix Figure 1XRD diffraction patterns of the catalyst Ni@BDC-ELC prepared according to the present invention, the comparative samples and their precursors:

[0015] Attached Figure 1 (a) Diffraction curve of Ni@BDC-ELC prepared in Example 1; Attached Figure 1 (b) Diffraction curve of Ni@BDCC prepared in Comparative Example 1; Attached Figure 1 (c) Diffraction curve of Ni@ELC prepared in Comparative Example 2; Attached Figure 1 (d) Diffraction curve of the catalyst precursor Ni-BDC-EL prepared in Comparative Example 4; Attached Figure 1 (e) Diffraction curve of the catalyst precursor Ni-BDC prepared in Comparative Example 5; Attached Figure 1 (f) Diffraction curve of the catalyst precursor Ni-EL prepared in Comparative Example 6.

[0016] Attached Figure 2 TEM image and particle size distribution of the catalyst Ni@BDC-ELC prepared according to the present invention.

[0017] Attached Figure 3 TEM image and particle size distribution of the comparative sample Ni@BDCC prepared according to the present invention.

[0018] Attached Figure 4 TEM image and particle size distribution of the comparative sample Ni@ELC prepared according to the present invention. Detailed implementation manners

[0019] The following examples are used to further illustrate the present invention, but do not limit the present invention thereby.

[0020]

Example 1

[0021] 10.8 mmol of nickel nitrate hexahydrate was stirred and dissolved in 30 mL of N,N-dimethylformamide to form solution A; 5.4 mmol of terephthalic acid and 0.2 g of enzymatically hydrolyzed lignin were stirred and dissolved in 30 mL of N,N-dimethylformamide to form solution B; under stirring, solution A and solution B were rapidly mixed in a Teflon-lined stainless steel autoclave and reacted at 120 °C for 24 h. After the reaction, the precursor Ni-BDC-EL was separated by filtration, washed 3 times with absolute ethanol, dried in vacuum at 80 °C for 12 h, and calcined in a tubular furnace at 500 °C for 2 h under a N2 atmosphere to obtain the lignin carbon-anchored metal Ni nanoparticle catalyst Ni@BDC-ELC based on the Ni-BDC MOF template. <s

[0022]

Example 2

[0023] Take 20 mg of the Ni@BDC-ELC catalyst prepared in Example 1 and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, and then charge 0.5 MPa of H2. React at 100 °C for 4 h with stirring at 600 rpm. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 1.

[0024]

Example 3

[0025] Take 20 mg of the Ni@BDC-ELC catalyst prepared in Example 1 and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, and then charge 0.5 MPa of H2. React at 120 °C for 4 h with stirring at 600 rpm. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 1.

[0026]

Example 4

[0027] Take 20 mg of the Ni@BDC-ELC catalyst prepared in Example 1 and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, and then charge 0.5 MPa of H2. React at 90 °C for 4 h with stirring at 600 rpm. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 1.

[0028]

Example 5

[0029] Take 20 mg of the Ni@BDC-ELC catalyst prepared in Example 1 and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, and then charge 1 MPa of H2. React at 80 °C for 4 h with stirring at 600 rpm. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 1.

[0030]

Example 6

[0031] Take 20 mg of the Ni@BDC-ELC catalyst prepared in Example 1 and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, and then charge 1 MPa of H2. React at 80 °C for 5 h with stirring at 600 rpm. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 1.

[0032]

Example 7

[0033] Take 20 mg of the Ni@BDC-ELC catalyst prepared in Example 1 and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, then charge 1 MPa of H2, and react at 80 °C with stirring at 600 rpm for 6 h. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 1.

[0034]

Example 8

[0035] Take 20 mg of the Ni@BDC-ELC catalyst prepared in Example 1 and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, then charge 1.5 MPa of H2, and react at 80 °C with stirring at 600 rpm for 4 h. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 1.

[0036]

Example 9

[0037] Take 20 mg of the Ni@BDC-ELC catalyst prepared in Example 1 and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, then charge 1 MPa of H2, and react at 100 °C with stirring at 600 rpm for 3 h. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 1.

[0038]

Example 10

[0039] Take 10 mg of the Ni@BDC-ELC catalyst prepared in Example 1 and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, then charge 1.5 MPa of H2, and react at 120 °C with stirring at 600 rpm for 4 h. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 1.

[0040] Table 1 Hydrogenation reaction performance of Ni@BDC-ELC, a Ni-based catalyst anchored by lignin carbon based on the Ni-BDC template

[0041]

[0042]

Examples 11 - 13

[0043] The solid catalyst recovered after centrifuging the reaction mixture in Example 2 was re - placed in a stainless - steel autoclave. 94 mg of phenol and 8 mL of deionized water were added. The air was displaced with hydrogen 4 - 5 times, and then 0.5 MPa of H2 was charged. The reaction was carried out at 100 °C for 4 h with stirring at 600 rpm. After the reaction, ethyl acetate was added for extraction and centrifugation. The supernatant was dried and quantitatively analyzed by gas chromatography. The recovered solid catalyst was reused by repeating the above operations for another 2 cycles. The catalytic results are shown in Table 2.

[0044] Table 2 Recycling stability of Ni@BDC - ELC for the hydrogenation of phenol to cyclohexanol

[0045]

[0046]

Comparative Example 1

[0047] 10.8 mmol of nickel nitrate hexahydrate was stirred and dissolved in 30 mL of N,N - dimethylformamide to form solution A; 5.4 mmol of terephthalic acid was stirred and dissolved in 30 mL of N,N - dimethylformamide to form solution B; under stirring, solution A and solution B were rapidly mixed in a Teflon - lined stainless - steel autoclave and reacted at 120 °C for 24 h. After the reaction, the precursor Ni - BDC was separated by filtration, washed 3 times with absolute ethanol, dried in vacuo at 80 °C for 12 h, and calcined in a tubular furnace at 500 °C for 2 h under a N2 atmosphere to obtain a metal Ni nanoparticle comparative catalyst Ni@BDCC based on the Ni - BDC MOF template.

[0048] 20 mg of the comparative catalyst Ni@BDCC and 94 mg of phenol were placed in a stainless - steel autoclave, 8 mL of deionized water was added as a solvent, the air was displaced with hydrogen 4 - 5 times, and then 0.5 MPa of H2 was charged. The reaction was carried out at 100 °C with stirring at 600 rpm for 4 h. After the reaction, ethyl acetate was added for extraction and centrifugation. The supernatant was dried and quantitatively analyzed by gas chromatography. The catalytic results are shown in Table 3.

[0049]

Comparative Example 2

[0050] 10.8 mmol of nickel nitrate hexahydrate was stirred and dissolved in 30 mL of N,N - dimethylformamide to form solution A; 0.2 g of enzymatically hydrolyzed lignin was stirred and dissolved in 30 mL of N,N - dimethylformamide to form solution B; under stirring, solution A and solution B were rapidly mixed in a Teflon - lined stainless - steel autoclave and reacted at 120 °C for 24 h. After the reaction, the precursor Ni - EL was separated by filtration, washed 3 times with absolute ethanol, dried in vacuo at 80 °C for 12 h, and calcined in a tubular furnace at 500 °C for 2 h under a N2 atmosphere to obtain a metal Ni nanoparticle comparative catalyst Ni@ELC anchored by lignin carbon.

[0051] Take 20 mg of the comparative catalyst Ni@ELC and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, and then fill with 0.5 MPa H2. React at 100 °C with stirring at 600 rpm for 4 h. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 3.

[0052]

Comparative Example 3

[0053] Stir 5.4 mmol of nickel nitrate hexahydrate and dissolve it in 30 mL of N,N-dimethylformamide to form solution A; stir 5.4 mmol of terephthalic acid and 0.2 g of enzymatically hydrolyzed lignin and dissolve them in 30 mL of N,N-dimethylformamide to form solution B; quickly mix solution A and solution B in a stainless-steel autoclave with a Teflon liner under stirring, and react at 120 °C for 24 h. After the reaction, filter to separate the precursor Ni-BDC'-EL, wash it 3 times with absolute ethanol, dry it in vacuo at 80 °C for 12 h, and calcine it in a tubular furnace under a N2 atmosphere at 500 °C for 2 h to obtain the comparative catalyst Ni@BDC'-ELC of lignin carbon-anchored metal Ni nanoparticles based on the Ni-BDC'MOF template.

[0054] Take 20 mg of the comparative catalyst Ni@BDC'-ELC and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, and then fill with 0.5 MPa H2. React at 100 °C with stirring at 600 rpm for 4 h. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 3.

[0055]

Comparative Example 4

[0056] Stir 10.8 mmol of nickel nitrate hexahydrate and dissolve it in 30 mL of N,N-dimethylformamide to form solution A; stir 5.4 mmol of terephthalic acid and 0.2 g of enzymatically hydrolyzed lignin and dissolve them in 30 mL of N,N-dimethylformamide to form solution B; quickly mix solution A and solution B in a stainless-steel autoclave with a Teflon liner under stirring, and react at 120 °C for 24 h. After the reaction, filter to separate the solid, wash it 3 times with absolute ethanol, and dry it in vacuo at 80 °C for 12 h to obtain the catalyst precursor Ni-BDC-EL.

[0057] Take 20 mg of the catalyst precursor Ni-BDC-EL and 94 mg of phenol in a stainless-steel autoclave, add 8 mL of deionized water as a solvent, displace the air with hydrogen 4 - 5 times, and then fill with 0.5 MPa H2. React at 100 °C with stirring at 600 rpm for 4 h. After the reaction, add ethyl acetate for extraction and centrifuge. After drying the supernatant, perform quantitative analysis by gas chromatography. The catalytic results are shown in Table 3.

[0058]

Comparative Example 5

[0059] 10.8 mmol of nickel nitrate hexahydrate was stirred and dissolved in 30 mL of N,N-dimethylformamide to form solution A; 5.4 mmol of terephthalic acid was stirred and dissolved in 30 mL of N,N-dimethylformamide to form solution B; solution A and solution B were rapidly mixed in a Teflon-lined stainless steel autoclave under stirring, and reacted at 120 °C for 24 h. After the reaction, the solid was separated by filtration, washed 3 times with absolute ethanol, and vacuum dried at 80 °C for 12 h to obtain the comparative catalyst precursor Ni-BDC.

[0060] 20 mg of the comparative catalyst precursor Ni-BDC and 94 mg of phenol were taken in a stainless steel high-pressure reaction kettle, 8 mL of deionized water was added as a solvent, the air was replaced with hydrogen 4-5 times, and then 0.5 MPa H2 was charged. The reaction was carried out at 100 °C for 4 h under stirring at 600 rpm. After the reaction, ethyl acetate was added for extraction and centrifugation. The supernatant was dried and quantitatively analyzed by gas chromatography. The catalytic results are shown in Table 3.

[0061]

Comparative Example 6

[0062] First, 10.8 mmol of nickel nitrate hexahydrate was stirred and dissolved in 30 mL of N,N-dimethylformamide to form solution A; 0.2 g of enzymatically hydrolyzed lignin was stirred and dissolved in 30 mL of N,N-dimethylformamide to form solution B; solution A and solution B were rapidly mixed in a Teflon-lined stainless steel autoclave under stirring, and reacted at 120 °C for 24 h. After the reaction, the solid was separated by filtration, washed 3 times with absolute ethanol, and vacuum dried at 80 °C for 12 h to obtain the comparative catalyst precursor Ni-EL.

[0063] 20 mg of the comparative catalyst precursor Ni-EL and 94 mg of phenol were taken in a stainless steel high-pressure reaction kettle, 8 mL of deionized water was added as a solvent, the air was replaced with hydrogen 4-5 times, and then 0.5 MPa H2 was charged. The reaction was carried out at 100 °C for 4 h under stirring at 600 rpm. After the reaction, ethyl acetate was added for extraction and centrifugation. The supernatant was dried and quantitatively analyzed by gas chromatography. The catalytic results are shown in Table 3.

[0064] Table 2 Catalytic performance of the comparative catalysts for the hydrogenation reaction of phenol

[0065]

Claims

1. A method for preparing cyclohexanol by catalytic hydrogenation of phenol in aqueous phase with Ni nanoparticles anchored on lignin carbon based on Ni-BDC template, which is characterized in that: Using Ni-BDC as a structure-directing agent and nickel source, and enzymatic lignin as a biomass carbon source, a catalyst precursor was obtained by a one-pot solvothermal method, and then a lignin carbon-anchored metal Ni nanoparticle based on the Ni-BDC template was prepared by pyrolysis carbonization reduction to catalyze the hydrogenation of phenol in aqueous phase to prepare cyclohexanol; The preparation method of the lignin carbon-anchored Ni nanoparticle catalyst based on the Ni-BDC template is as follows: nickel nitrate hexahydrate was dissolved in N,N-dimethylformamide to form solution A at a ratio of 10.8 mmol of nickel salt per 30 mL of solvent; terephthalic acid and enzymatic lignin were dissolved in N,N-dimethylformamide to form solution B at a ratio of 5.4 mmol of terephthalic acid and 0.2 g of enzymatic lignin per 30 mL of solvent; the mixed solution of solution A and solution B was reacted in a Teflon-lined stainless steel autoclave at 120 °C for 24 h; after the reaction, the solid was filtered and separated, washed 3 times with ethanol, dried in vacuum at 80 °C for 12 h, and calcined in a tubular furnace at 500 °C for 2 h in a N2 atmosphere to obtain a lignin carbon-anchored metal Ni nanoparticle catalyst based on the Ni-BDC template; The method for preparing cyclohexanol by hydrogenation of phenol in aqueous phase is as follows: in a reaction kettle, phenol as a raw material and water as a solvent were added respectively at a ratio of 8 mL of solvent per mmol of raw material, and the lignin carbon-anchored metal Ni nanoparticle catalyst based on the Ni-BDC template was added at a ratio of 10-20 mg of catalyst per mmol of raw material under stirring, and the reaction was carried out at a H2 pressure of 0.5-1.5 MPa and a temperature of 80-120 °C for 2-6 h. After the reaction, the product was extracted with ethyl acetate, and the catalyst was separated and recovered and directly recycled.

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