A method for preparing cyclopentanone by one-pot catalytic hydrogenation of xylose

Abstract

The present invention provides a method for preparing cyclopentanone by one-pot process using catalytic hydrogenation of xylose. The method adopts niobium pentoxide loaded metal catalyst, converts xylose into furfural in a two-phase reaction system under nitrogen atmosphere, and then realizes one-pot preparation of cyclopentanone through isomerization and hydrodeoxygenation steps under hydrogenation reaction conditions by gas replacement operation. Under optimal conditions, the xylose substrate is completely converted, and the corresponding cyclopentanone yield is 55%. In particular, under the reaction condition of substrate mass fraction up to 10%, the yield of cyclopentanone can still reach 47%, which is conducive to the enrichment of post-reaction products and the separation of downstream products. Compared with the prior art, the present invention proposes to use relatively cheap xylose as raw material to realize efficient production of cyclopentanone by one-pot process, the method has a short process route, a simple catalyst preparation process, a high reaction substrate concentration, can greatly reduce the later separation cost, and is expected to produce considerable economic benefits.

Description

Technical Field

[0001] The invention belongs to the field of high-value catalytic conversion of biomass, and relates to a method for preparing cyclopentanone by one-pot catalytic hydrogenation of xylose. The method is a process for preparing cyclopentanone by one-pot conversion in a two-phase reaction system using xylose as a raw material. Background Art

[0002] As an important chemical raw material, cyclopentanone can be widely used as an intermediate for the synthesis of pharmaceuticals, pesticides, rubber and fragrances. Currently, the production of cyclopentanone is mainly through traditional fossil raw material refining synthesis routes such as liquid phase oxidation of cyclopentene, cyclodehydration of 1,6-hexanediol or adipic acid. These production processes not only consume a large amount of non-renewable fossil resources and produce greenhouse gases, but also require harsh reaction conditions. With the increasing consumption of fossil resources and the increasing prominence of environmental problems, the development of green and efficient bio-based cyclopentanone production methods has great strategic significance.

[0003] The direct and selective conversion of bio-based platform chemical furfural into cyclopentanone has been a hot topic in the field of biomass catalysis in recent years. This conversion process usually uses highly active hydrogenation metals as catalysts to hydrogenate furfural molecules to obtain furfuryl alcohol, and then Piancatelli rearrangement occurs under the participation of protonic acids in an aqueous environment to form 4-hydroxy-2-cyclopentenone, which is then hydrogenated to obtain cyclopentanone. Over-hydrogenation of cyclopentanone generates cyclopentanol. However, in this process, furfural is prone to polymerization and coking, which reduces carbon balance and has low substrate conversion efficiency. In addition, the preparation of furfural requires a series of steps such as hydrolysis, dehydration, isomerization, and distillation purification, and the raw material price is high, which seriously affects the economic competitiveness of bio-based cyclopentanone and petroleum-based products. Therefore, it is of high technical and economic value to develop a one-pot method for preparing cyclopentanone using cheaper sugar-based raw materials as reaction substrates through catalyst design and reaction process optimization. Summary of the invention

[0004] To solve the above problems, the present invention provides a method for directly preparing cyclopentanone by a one-pot process using xylose as a raw material. The technical scheme in the embodiments of the present invention will be described in detail below. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present invention.

[0005] The reaction of preparing cyclopentanone from xylose is carried out in a stainless steel high-pressure reactor equipped with a magnetic stirrer. The reaction includes two stages, namely dehydration isomerization and hydrogenation rearrangement. First, a certain amount of xylose raw material, solvent and catalyst are added to the reactor, nitrogen is filled into the reactor and purged repeatedly three times, and the reactor is pressurized to a certain pressure and heated to the reaction temperature for the first stage reaction. After the reaction is completed, the reaction gas is emptied, hydrogen is filled into the reactor and purged repeatedly three times, and the reactor is pressurized to a certain pressure and heated to the reaction temperature for the second stage reaction.

[0006] The present invention adopts the following technical scheme: a method for preparing cyclopentanone by catalytic hydrogenation of xylose in one pot, comprising the following steps:

[0007] (1) First, xylose raw material, solvent and catalyst are added to the reactor, nitrogen is filled into the reactor for purging, pressurizing, and heating to the reaction temperature to carry out the first stage reaction;

[0008] (2) After the first stage reaction is completed, the reaction gas is evacuated, hydrogen is filled into the reactor for purging, pressurizing, and heating to the reaction temperature to carry out the second stage reaction to obtain the cyclopentanone.

[0009] In the present invention, the reaction solvent is a biphasic solvent, including an aqueous phase and an organic phase that is immiscible therewith, and representative solvents of the organic phase are ethyl acetate, benzene, toluene, tetrahydrofuran, dichloromethane or methyl isobutyl ketone, etc. The volume ratio of the solvent of the aqueous phase and the organic phase that is immiscible therewith is 1:3 to 3:1. For example, the organic phase is toluene, methyl isobutyl ketone or tetrahydrofuran.

[0010] Further, in step (1), the volume ratio of the aqueous phase to the solvent of the organic phase that is immiscible therewith is 1:3, 1:2.8, 1:2.6, 1:2.4, 1:2.2, 1:2, 1:1.8, 1:1.6, 1:1.4, 1:1.2, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3:1.

[0011] In the present invention, the first stage reaction atmosphere is nitrogen, and the initial nitrogen pressure is preferably 0.1-4 MPa; the first stage reaction temperature is preferably 120-180°C; the first stage stirring speed is preferably 500-800 rpm; the first stage reaction time is preferably 4-8 hours. For example, the initial nitrogen pressure is 0.1 MPa, 0.3 MPa, 0.7 MPa, 1 MPa, 1.2 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa or 4 MPa. For example, the first stage reaction temperature is 120°C, 130°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C or 180°C. For example, the stirring speed in the first stage is 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm or 800 rpm. For example, the first stage reaction time is 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours or 8 hours.

[0012] In the present invention, the second stage reaction atmosphere is hydrogen, and the initial pressure of hydrogen is preferably 1-4 MPa; for example, the initial pressure of hydrogen is 1 MPa, 1.2 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa or 4 MPa; the second stage reaction temperature is preferably 120-180 ° C; the second stage stirring speed is preferably 500-800 rpm; the second stage reaction time is preferably 3-6 hours. For example, the second stage stirring speed is 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm or 800 rpm. For example, the second stage reaction temperature is preferably 120 ° C, 130 ° C, 140 ° C, 150 ° C, 160 ° C, 165 ° C, 170 ° C, 175 ° C or 180 ° C. For example, the second stage reaction time is 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours.

[0013] Furthermore, in step (1), the catalyst comprises a niobium pentoxide-supported Co, Ni, Mo, Mn, Cu, Ru or Pt metal catalyst, preferably a Co metal catalyst supported by niobium pentoxide. For example, the catalyst consists of niobium pentoxide and Co, Ni, Mo, Mn, Cu, Ru or Pt metal supported on niobium pentoxide.

[0014] Furthermore, in step (1), the catalyst is a niobium pentoxide-supported Co, Ni, Mo, Mn, Cu, Ru or Pt metal catalyst, and the preparation method of the catalyst is as follows:

[0015] A metal nitrate hydrate precursor solution and a niobium pentoxide carrier are mixed, wherein the metal is Co, Ni, Mo, Mn, Cu, Ru or Pt; the mixture is stirred and impregnated at room temperature, and then the solvent is dried and evaporated; the obtained solid is ground, sieved for the first time, roasted, and cooled to obtain a calcined material; the obtained calcined material is ground, sieved for a second time, and reduced in a 10% hydrogen / argon mixed gas to prepare an active catalyst.

[0016] Furthermore, in the catalyst, the mass percentage of the metal is 2.5% to 25% based on the total mass of the catalyst. For example, the mass percentage of the metal is 2.5%, 3.0%, 4.0%, 5.0%, 5.5%, 6.0%, 7.0%, 9.0%, 10.0%, 10.5%, 11.0%, 12.0%, 13.0%, 15.0%, 18.0%, 20.0%, 23.0% or 25.0% based on the total mass of the catalyst.

[0017] Further, the first screening obtains catalyst precursor particles with a particle size of 50-80 mesh (e.g., 50 mesh, 55 mesh, 60 mesh, 65 mesh, 70 mesh, 75 mesh or 80 mesh) for calcination; preferably, the calcination temperature is 400-800°C (e.g., the calcination temperature is 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C), and the calcination time is 2-5 hours (e.g., calcination for 2 hours, 3 hours, 4 hours or 5 hours); preferably, the second screening obtains catalyst precursor particles with a particle size of 50-80 mesh (e.g., 50 mesh, 55 mesh, 60 mesh, 650 mesh, 700 mesh, 750 mesh or 800 mesh) for calcination; preferably, the calcination temperature is 400-800°C (e.g., the calcination temperature is 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C), and the calcination time is 2-5 hours (e.g., calcination for 2 hours, 3 hours, 4 hours or 5 hours). The first sieving obtains particles with a particle size of 70 mesh-100 mesh (for example, 70 mesh, 75 mesh, 80 mesh, 85 mesh, 90 mesh, 95 mesh or 100 mesh) for reduction; preferably, the reduction temperature is 300-600°C (for example, the reduction temperature is 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 550°C or 600°C), and the reduction time is 1-3 hours (for example, the reduction time is 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours).

[0018] Further, in step (1), the mass ratio of xylose raw material to catalyst is 1 to 15: 1. In step (1), the mass ratio of xylose raw material to catalyst is 1: 1, 2: 1, 3: 1, 4: 1, 6: 1, 8: 1, 10: 1, 12: 1, 13: 1 or 15: 1.

[0019] Further, in step (1), the ratio of xylose raw material to solvent is 0.2-5 g:20 ml. For example, the ratio of xylose raw material to solvent is 0.2 g:20 ml, 0.3 g:20 ml, 0.4 g:20 ml, 0.5 g:20 ml, 0.6 g:20 ml, 0.8 g:20 ml, 1.0 g:20 ml, 1.5 g:20 ml, 2.0 g:20 ml, 2.5 g:20 ml, 3.0 g:20 ml, 3.5 g:20 ml, 4.0 g:20 ml, 4.6 g:20 ml, 4.8 g:20 ml or 5.0 g:20 ml.

[0020] In the present invention, the catalyst is preferably a cobalt metal catalyst supported by niobium pentoxide; the niobium pentoxide carrier is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. As a control, H-β molecular sieve (Nankai University Catalyst Factory), ZSM-5 (Nankai University Catalyst Factory), Al2O3 (Guangdong Chemical Reagent Factory Technology Research and Development Center), TiO2 (Shanghai Aladdin Biochemical Technology Co., Ltd.), ZrO2 (Shanghai Aladdin Biochemical Technology Co., Ltd.), CeO2 (Shanghai Aladdin Biochemical Technology Co., Ltd.) or SiO2 (Shanghai Aladdin Biochemical Technology Co., Ltd.) are used as carriers to prepare control catalysts under the same operating conditions.

[0021] The catalyst described in the following embodiments of the present invention includes niobium pentoxide-supported Co, Ni, Mo, Mn, Cu, Ru, and Pt metal catalysts. The preparation method is as follows:

[0022] Weigh a certain mass of metal nitrate hydrate precursor into a beaker, add about 100 ml of deionized water and 100 ml of ethanol and stir at room temperature for 30 minutes to form a uniform solution. Add a certain mass of niobium pentoxide carrier to the solution, calculate the ratio of metal precursor and carrier, and prepare x% metal (metal is Co, Ni, Mo, Mn, Cu, Ru, Pt) / carrier (based on the total mass of the catalyst, the metal content is x%). The impregnation is completed by stirring at room temperature for 24 hours with a magnetic stirrer, and then transferred to an 80°C oven to dry and evaporate the solvent. The obtained solid is ground into a fine powder, sieved through a 50-80 mesh screen to obtain catalyst precursor particles with a particle size of 50-80 mesh, and the 50-80 mesh catalyst precursor particles are transferred to a quartz boat. Continuously roast at a constant temperature of 600°C for 3 hours in a muffle furnace, and the calcined material is obtained after cooling. The obtained solid was ground into fine powder, and sieved through a 70-100 mesh screen to obtain particles with a particle size of 70-100 mesh. The 70-100 mesh particles were added to a tubular furnace and reduced with 10% hydrogen / argon mixed gas (10% hydrogen / argon means that the volume percentage of hydrogen is 10% based on the total volume of the hydrogen and argon mixed gas) at 450° C. for 2 hours to prepare an active catalyst, which was placed in a desiccator for storage.

[0023] The beneficial effects of the present invention are:

[0024] 1. The method for preparing cyclopentanone in one pot using xylose as raw material reported in the present invention can reduce the raw material cost of the previous process for preparing cyclopentanone using furfural, avoid the separation and purification process of furfural, shorten the production cycle, and improve the production efficiency of cyclopentanone.

[0025] 2. The present invention adopts Nb2O5 as a solid acid and a hydrogenation metal carrier, realizes the matching use of catalysts in the xylose dehydration and furfural hydrogenation stages, avoids the use of homogeneous acids (sulfuric acid, hydrochloric acid, etc.), improves the recyclability of the catalyst, reduces the coking degree of the raw materials by constructing a two-phase solvent system, and improves the overall cyclopentanone yield.

[0026] 3. The present invention adopts non-precious metal Co as the hydrogenation metal species, avoiding the traditional precious metal as the hydrogenation active phase. The cobalt metal precursor salt is cheap and widely available, and is suitable for large-scale preparation, laying the foundation for the mass production of cyclopentanone. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below in conjunction with specific examples. These examples are only for illustrating the present invention, but the present invention is not limited to the following examples.

[0028] Example 1: Take 0.3g xylose, add 10mL toluene (as organic phase solvent) and 10mL water mixed solution, place in a 50mL pressure reaction vessel, add 0.15g 10% Co / Nb2O5 catalyst. Replace the gas atmosphere with nitrogen, and adjust the initial nitrogen pressure to 2MPa, stir and mix evenly at 600 rpm, react at 170℃ reaction temperature for 6 hours and then cool to room temperature; replace the gas atmosphere with hydrogen, and adjust the initial hydrogen pressure to 2MPa, react at 160℃ reaction temperature for 4 hours, cool to room temperature, and the reaction product is quantitatively analyzed by gas chromatography, and the cyclopentanone yield is 55%. The specific results are shown in Table 1.

[0029] Example 2: A 10% Ni / Nb2O5 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 1. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 1.

[0030] Example 3: A catalyst of 10% Mo / Nb2O5 was selected, and the reaction materials and reaction conditions were the same as those in Example 1. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 1.

[0031] Example 4: A 10% Mn / Nb2O5 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 1. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 1.

[0032] Example 5: A catalyst of 10% Cu / Nb2O5 was selected, and the reaction materials and reaction conditions were the same as those in Example 1. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 1.

[0033] Example 6: A catalyst of 10% Ru / Nb2O5 was selected, and the reaction materials and reaction conditions were the same as those in Example 1. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 1.

[0034] Example 7: A 10% Pt / Nb2O5 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 1. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 1.

[0035] Table 1 Yields of cyclopentanone prepared with different loaded metals (wherein, substrate concentration = (substrate mass g / (solvent total volume ml))*100%)

[0036] Example catalyst Substrate and concentration Conversion rate Cyclopentanone yield 1 <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose >99％ 55％ 2 <![CDATA[10%Ni / Nb2O5]]> 1.5% Xylose >99％ 31％ 3 <![CDATA[10%Mo / Nb2O5]]> 1.5% Xylose >99％ 16％ 4 <![CDATA[10%Mn / Nb2O5]]> 1.5% Xylose >99％ 4％ 5 <![CDATA[10%Cu / Nb2O5]]> 1.5% Xylose >99％ 3％ 6 <![CDATA[10%Ru / Nb2O5]]> 1.5% Xylose >99％ 10％ 7 <![CDATA[10%Pt / Nb2O5]]> 1.5% Xylose >99％ 13％

[0037] It can be seen from Examples 1-7 that the catalysts prepared by loading Co, Ni, Mo, Mn, Cu, Ru, and Pt on a Nb2O5 carrier can catalyze the one-pot conversion of xylose to produce cyclopentanone, among which 10% Co / Nb2O5 has the highest cyclopentanone yield, reaching 55%. In comparison, the cyclopentanone yields prepared by the precious metal catalysts Ru and Pt are lower.

[0038] Example 8: Take 0.3g of xylose, add 10mL of toluene (as an organic phase solvent) and 10mL of water mixed solution, place in a 50mL pressure reaction vessel, add 0.15g of 3% Co / Nb2O5 catalyst. Replace the gas atmosphere with nitrogen, and adjust the initial nitrogen pressure to 2MPa, stir and mix evenly at 600 rpm, react at a reaction temperature of 170°C for 6 hours and then cool to room temperature; replace the gas atmosphere with hydrogen, and adjust the initial hydrogen pressure to 2MPa, react at a reaction temperature of 160°C for 4 hours, cool to room temperature, and the reaction product is quantitatively analyzed by gas chromatography, and the cyclopentanone yield is 30%. The specific results are shown in Table 2.

[0039] Example 9: A 5% Co / Nb2O5 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 8. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 2.

[0040] Example 10: A 10% Co / Nb2O5 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 8. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 2.

[0041] Example 11: A 15% Co / Nb2O5 catalyst was selected. The reaction materials and reaction conditions were the same as those in Example 8. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 2.

[0042] Example 12: A 20% Co / Nb2O5 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 8. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 2.

[0043] Table 2 Yield of cyclopentanone prepared with different Co metal loadings (wherein, substrate concentration = (substrate mass g / (solvent total volume ml))*100%)

[0044] Example catalyst Substrate and concentration Conversion rate Cyclopentanone yield 8 <![CDATA[3%Co / Nb2O5]]> 1.5% Xylose >99％ 30％ 9 <![CDATA[5%Co / Nb2O5]]> 1.5% Xylose >99％ 47％ 10 <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose >99％ 55％ 11 <![CDATA[15%Co / Nb2O5]]> 1.5% Xylose >99％ 43％ 12 <![CDATA[20%Co / Nb2O5]]> 1.5% Xylose >99％ 39％

[0045] It can be seen from Examples 8-12 that the highest cyclopentanone yield, reaching 55%, can be obtained when the Co loading on the Nb2O5 carrier is 10%.

[0046] Example 13: Take 0.3g of xylose, add 10mL of toluene (as an organic phase solvent) and 10mL of water mixed solution, place in a 50mL pressure reaction vessel, add 0.15g of 10% Co / Nb2O5 catalyst. Replace the gas atmosphere with nitrogen, and adjust the initial nitrogen pressure to 2MPa, stir and mix evenly at 600 rpm, react at a reaction temperature of 170°C for 6 hours and then cool to room temperature; replace the gas atmosphere with hydrogen, and adjust the initial hydrogen pressure to 2MPa, react at a reaction temperature of 160°C for 4 hours, cool to room temperature, and the reaction product is quantitatively analyzed by gas chromatography, and the cyclopentanone yield is 55%. The specific results are shown in Table 3.

[0047] Example 14: A 10% Co / H-β catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 13. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 3.

[0048] Example 15: A 10% Co / ZSM-5 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 13. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 3.

[0049] Example 16: A 10% Co / Al2O3 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 13. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 3.

[0050] Example 17: A 10% Co / TiO2 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 13. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 3.

[0051] Example 18: A 10% Co / ZrO2 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 13. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 3.

[0052] Example 19: A 10% Co / CeO2 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 13. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 3.

[0053] Example 20: A 10% Co / SiO2 catalyst was selected, and the reaction materials and reaction conditions were the same as those in Example 13. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 3.

[0054] Table 3 Yields of cyclopentanone prepared by using Co loaded on different carriers (wherein, substrate concentration = (substrate mass g / (solvent total volume ml))*100%)

[0055] Example catalyst Substrate and concentration Conversion rate Cyclopentanone yield 13 <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose >99％ 55％ 14 10%Co / H-β 1.5% Xylose >99％ 38％ 15 10%Co / ZSM-5 1.5% Xylose 66％ 34％ 16 <![CDATA[10%Co / Al2O3]]> 1.5% Xylose >99％ 31％ 17 <![CDATA[10%Co / TiO2]]> 1.5% Xylose 58％ 14％ 18 <![CDATA[10%Co / ZrO2]]> 1.5% Xylose 92％ 39％ 19 <![CDATA[10%Co / CeO2]]> 1.5% Xylose 83％ 19％ 20 <![CDATA[10%Co / SiO2]]> 1.5% Xylose 47％ 8％

[0056] It can be seen from Examples 13-20 that the highest cyclopentanone yield of 55% can be obtained when Nb2O5 is used as a carrier to load Co.

[0057] Example 21: Take 0.3g of xylose and add 10mL of toluene (as an organic phase solvent) and 10mL of water mixed solution, place in a 50mL pressure reaction vessel, add 0.15g of 10% Co / Nb2O5 catalyst. Replace the gas atmosphere with nitrogen, and adjust the initial nitrogen pressure to 2MPa, stir and mix evenly at 600 rpm, react at a reaction temperature of 170°C for 6 hours and then cool to room temperature; replace the gas atmosphere with hydrogen, and adjust the initial hydrogen pressure to 2MPa, react at a reaction temperature of 160°C for 4 hours, cool to room temperature, and the reaction product is quantitatively analyzed by gas chromatography, and the cyclopentanone yield is 55%. The specific results are shown in Table 4.

[0058] Example 22: Ethyl acetate was selected as the organic phase solvent. The reaction materials and reaction conditions were the same as those in Example 21. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 4.

[0059] Example 23: Dichloromethane was selected as the organic phase solvent. The reaction materials and reaction conditions were the same as those in Example 21. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 4.

[0060] Example 24: Benzene was selected as the organic phase solvent. The reaction materials and reaction conditions were the same as those in Example 21. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 4.

[0061] Example 25: Methyl isobutyl ketone was selected as the organic phase solvent. The reaction materials and reaction conditions were the same as those in Example 21. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 4.

[0062] Example 26: Tetrahydrofuran was selected as the organic phase solvent, and the reaction materials and reaction conditions were the same as those in Example 21. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 4.

[0063] Table 4 Yields of cyclopentanone prepared in different organic solvent-water phase systems (wherein, substrate concentration = (substrate mass g / (solvent total volume ml))*100%)

[0064] Example Organic solvents catalyst Substrate and concentration Conversion rate Cyclopentanone yield 21 Toluene <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose >99％ 55％ 22 Ethyl acetate <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose >99％ 27％ 23 Dichloromethane <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose 76％ 5％ 24 benzene <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose 83％ 20％ 25 Methyl isobutyl ketone <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose >99％ 39％ 26 Tetrahydrofuran <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose >99％ 34％

[0065] It can be seen from Examples 21-26 that the highest cyclopentanone yield of 55% can be obtained in the toluene and water phase reaction system.

[0066] Example 27: Take 0.3g of xylose and add 10mL of toluene (as an organic phase solvent) and 10mL of water mixed solution, place in a 50mL pressure reaction vessel, add 0.15g of 10% Co / Nb2O5 catalyst. Replace the gas atmosphere with nitrogen, and adjust the initial nitrogen pressure to 2MPa, stir and mix evenly at 600 rpm, react at a reaction temperature of 170°C for 6 hours and then cool to room temperature; replace the gas atmosphere with hydrogen, and adjust the initial hydrogen pressure to 2MPa, react at a reaction temperature of 160°C for 4 hours, cool to room temperature, and perform GC quantitative analysis on the product. The yield of cyclopentanone is 55%. The specific results are shown in Table 5.

[0067] Example 28: 0.6 g of xylose was added as a substrate, and the amount of catalyst added was 0.3 g. The reaction system and reaction conditions were the same as those in Example 27. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 5.

[0068] Example 29: 2.0 g of xylose was added as a substrate, 1.0 g of catalyst was added, the reaction system and reaction conditions were the same as in Example 27, and the relevant substrate conversion rate and product selectivity data were calculated and shown in Table 5.

[0069] Example 30: 3.0 g of xylose was added as a substrate, 1.5 g of catalyst was added, the reaction system and reaction conditions were the same as in Example 27, and the relevant substrate conversion rate and product selectivity data were calculated and shown in Table 5.

[0070] Example 31: 4.0 g of xylose was added as a substrate, 2.0 g of catalyst was added, the reaction system and reaction conditions were the same as in Example 27, and the relevant substrate conversion rate and product selectivity data were calculated and shown in Table 5.

[0071] Example 32: 0.3 g of xylan (Shanghai MacLean Biochemical Technology Co., Ltd.) was added as a substrate. The reaction system and reaction conditions were the same as those in Example 27. The relevant substrate conversion rate and product selectivity data were calculated and shown in Table 5.

[0072] Table 5 Yield of cyclopentanone prepared in different concentrations of substrate (wherein, substrate concentration = (substrate mass g / (solvent total volume ml))*100%)

[0073] Example catalyst Substrate and concentration Conversion rate (%) Cyclopentanone yield (%) 27 <![CDATA[10%Co / Nb2O5]]> 1.5% Xylose >99％ 55％ 28 <![CDATA[10%Co / Nb2O5]]> 3% Xylose >99％ 53％ 29 <![CDATA[10%Co / Nb2O5]]> 10% Xylose 74％ 47％ 30 <![CDATA[10%Co / Nb2O5]]> 15% Xylose 55％ 40％ 31 <![CDATA[10%Co / Nb2O5]]> 20% Xylose 42％ 24％ 32 <![CDATA[10%Co / Nb2O5]]> 1.5% Xylan >99％ 35％

[0074] It can be seen from Examples 27-32 that the higher the xylose concentration, the lower the cyclopentanone yield obtained, and a 47% cyclopentanone yield can still be obtained at a substrate concentration of 10%. In addition, the catalytic system also has a certain catalytic activity for the preparation of cyclopentanone from xylan.

[0075] The present invention does not elaborate on some of the common technologies of those skilled in the art. The above-described embodiments are only descriptions of preferred implementations of the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementations described. Without departing from the design spirit of the present invention, various modifications and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing cyclopentanone by one-pot catalytic hydrogenation of xylose, characterized in that: The following steps are involved: (1) First, xylose raw material, solvent and catalyst are added to the reactor, nitrogen is filled into the reactor for purging, pressurizing, and heating to the reaction temperature for the first stage reaction; (2) After the first stage reaction is completed, the reaction gas is evacuated, hydrogen is filled into the reactor for purging, pressurizing, and heating to the reaction temperature to carry out the second stage reaction to obtain the cyclopentanone; In step (1), the solvent is a biphasic solvent, including an aqueous phase and an organic phase that is immiscible therewith, the solvent of the organic phase is one or more of ethyl acetate, benzene, toluene, tetrahydrofuran, dichloromethane and methyl isobutyl ketone; the volume ratio of the aqueous phase to the solvent of the organic phase that is immiscible therewith is 1:3 to 3:1; In step (1), the first stage reaction is carried out at an initial nitrogen pressure of 0.1-4 MPa and a reaction temperature of 120-180° C. for 4-8 hours and then cooled to room temperature; the stirring speed of the first stage is 500-800 rpm; In step (2), the reaction atmosphere in the second stage is hydrogen, and the initial pressure of hydrogen is 1-4 MPa; the reaction temperature in the second stage is 120-180°C; the stirring speed in the second stage is 500-800 rpm; The second stage reaction time is 3 to 6 hours; In step (1), the catalyst is a Co metal catalyst supported by niobium pentoxide, and the mass percentage of the metal in the catalyst is 5.5% to 23% based on the total mass of the catalyst.

2. The method according to claim 1, characterized in that In step (1), the preparation method of the catalyst is as follows: A metal nitrate hydrate precursor solution and a niobium pentoxide carrier are mixed, wherein the metal is Co; the mixture is stirred and impregnated at room temperature, and then the solvent is dried and evaporated; the obtained solid is ground, sieved for the first time, roasted, and cooled to obtain a calcined material; the obtained calcined material is ground, sieved for a second time, and reduced in a hydrogen / argon mixed gas to prepare an active catalyst; wherein the hydrogen content in the hydrogen / argon mixed gas is 10% based on the total volume of the hydrogen and argon mixed gas.

3. The method according to claim 1, characterized in that: In the catalyst, the mass percentage of the metal is 5.5% to 15% based on the total mass of the catalyst.

4. The method according to claim 2, characterized in that: The first screening obtains catalyst precursor particles with a particle size of 50-80 mesh for calcination; the calcination temperature is 400-800°C and the calcination time is 2-5 hours; the second screening obtains particles with a particle size of 70-100 mesh for reduction; the reduction temperature is 300-600°C and the reduction time is 1-3 hours.

5. The method according to claim 1, characterized in that In step (1), the mass ratio of xylose raw material to catalyst is 1-15:

1.

6. The method according to claim 1, characterized in that In step (1), the ratio of xylose raw material to solvent is 0.2~5g:20ml.