Method for preparing ketone compounds by catalyzing cellulose hydrogenation through Pd-TiO2 / C supported catalyst

Abstract

The invention discloses a method for preparing ketone compounds by catalyzing cellulose hydrogenation through a Pd-TiO2 / C supported catalyst. According to the method, cellulose is taken as a raw material, Pd-TiO2 / C is taken as a catalyst, a deionized water solution is taken as a solvent, a reaction is carried out for 2-6 hours under the conditions that the pressure of a hydrogen source gas consisting of hydrogen and carbon monoxide is 1-5 MPa and the temperature is 190-250 DEG C, and the ketone compound mainly comprising 2, 5-hexanedione is obtained. The reaction provided by the invention has the advantages of renewable raw materials, environment friendliness, mild conditions, high selectivity and the like, and an effective way for preparing the ketone compounds from biomass is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic hydrogenation, and in particular to the application of a Pd-TiO2 / C supported catalyst in the reaction of catalyzing the hydrogenation of cellulose to prepare ketone compounds in a non-pure hydrogen mixed atmosphere with a CO content of 0.5% to 60%. Background Art

[0002] Lignocellulosic biomass mainly comes from agricultural and forestry processing byproducts and agricultural and forestry wastes. It is a renewable resource with huge reserves and convenient access. It is one of the most promising raw materials for the production of chemicals and biofuels. Therefore, it is considered an important renewable resource that can replace fossil resources. Cellulose is the main component of lignocellulose. It is a linear polymer formed by glucose linked by β-1,4-glycosidic bonds. Glucose is the primary product of cellulose hydrolysis and an important platform compound. Cellulose can be further converted into a variety of high-value downstream chemicals through hydrolysis.

[0003] The catalytic hydrogenation process is an important process in modern industry and a key step in the production of clean fuels and high-end chemicals. It is reported that catalytic hydrogenation accounts for more than 30% of the entire chemical industry system. Catalytic cellulose hydrogenation refers to the chemical reaction process in which cellulose and hydrogen are converted into downstream products under the action of catalysts. Due to the stubborn three-dimensional crystal network structure of cellulose, the directional conversion of cellulose needs to be carried out under harsh conditions such as a high-pressure hydrogen atmosphere.

[0004] The precious metal palladium (Pd) is widely used to catalyze the hydrogenation of cellulose. However, due to its extremely strong hydrogenation performance, it will non-selectively hydrogenate all functional groups, resulting in over-hydrogenation of the reaction products. The purity of hydrogen currently used in industrial production is higher than 99.99%. Crude hydrogen is mainly obtained through reforming reactions such as coal hydrogen production (including direct hydrogen production and indirect hydrogen production such as methanol cracking hydrogen production), biohydrogen production, and hydrocarbon hydrogen production. The CO in the crude hydrogen is purified by pressure swing adsorption, membrane separation or cryogenic separation to produce high-purity hydrogen. In the catalytic hydrogenation process, although the use of crude hydrogen as a hydrogen source has the characteristics of simple industrial equipment and higher economy (only half of pure hydrogen), the small amount of CO contained in the crude hydrogen will cause the hydrogenation catalyst (such as precious metal Pd) to deactivate quickly. This is attributed to the strong interaction between the contained CO and the metal site Pd. During the catalytic reaction, CO is strongly adsorbed on the surface of the precious metal to occupy the catalytic active site, so that the reactant molecules cannot be adsorbed on the catalyst surface, resulting in the catalyst being "poisoned" and deactivated. Therefore, the reported catalytic cellulose hydrogenation reaction requires high-purity hydrogen with a purity higher than 99.99% as a hydrogen source to avoid poisoning of the catalyst by CO. Therefore, developing cellulose hydrogenation catalysts that can inhibit over-hydrogenation and improve CO tolerance, or even directly using crude hydrogen for catalytic hydrogenation reactions, thereby reducing hydrogenation costs and the complexity of industrial catalytic devices, is a major challenge in this research field, which is extremely attractive in terms of both economic value and scientific significance.

[0005] Cellulose is abundant in nature. Many downstream chemicals can be obtained by catalytic conversion of cellulose. Among them, 2,5-hexanedione is an important organic chemical intermediate with a molecular formula of C6H 10 O2 is a colorless liquid at room temperature and is miscible with water, ethanol, etc. 2,5-Hexanedione is widely used in the synthesis of pharmaceuticals, pesticides, colorants, and resin materials, and has a wide range of applications in industrial production and daily consumption. 2,5-Hexanedione contains unsaturated carbon-oxygen double bond functional groups, which can undergo aldol condensation reactions with itself (commonly dicondensation or tricondensation) to achieve carbon chain growth and produce high-density aviation biofuels.

[0006] At present, the main method for the industrial production of 2,5-hexanedione is the 2,5-dimethylfuran hydrolysis method, which is obtained by hydrolysis and ring opening of furan. This method has few raw material sources, high cost and high toxicity. Another synthesis method is to react sodium acetoacetate with pure iodine to produce diethyl diacetyl succinate, and then obtain high-purity 2,5-hexanedione through subsequent hydrolysis, extraction, fractionation and other steps. The disadvantages of this method are complicated steps, high raw material costs, serious environmental pollution, and it is only suitable for small-scale production in the laboratory. Compared with the above raw materials, cellulose has a wide source and low price, and its development and utilization has less pollution to the environment. Glucose, the constituent monomer of cellulose, is a C6 compound. The conversion of glucose to produce 2,5-hexanedione has a 100% carbon atom utilization efficiency, so the production of 2,5-hexanedione using cellulose as a substrate has become a research hotspot.

[0007] Chinese invention patent CN114057554B discloses a method for preparing 2,5-hexanedione by catalytic hydrogenation of lignocellulose, which uses lignocellulose as raw material, liquid acid aqueous solution as solvent, graphene carbon nanotube / carbon shell wrapped metal material as catalyst, hydrogen pressure of 1~6 MPa, reaction temperature of 180~260℃, and reaction time of 0.5~6 h. Although this method can obtain a higher yield of ketones, the production cost is high because a large amount of high-purity hydrogen is required for the reaction. It uses liquid acid aqueous solution as solvent, which is easy to corrode the reaction equipment, puts forward higher requirements for the selection of equipment, and the reaction products are not easy to separate, making it difficult to industrialize.

[0008] Flora Chambon et al. (Flora Chambon, Franck Rataboul, Catherine Pinel, et al. Conversion of cellulose to 2,5-hexanedione using tungstated zirconia inhydrogen atmosphere[J]. Applied Catalysis A: General, 2015, 504(5), 664-671.) reported the preparation of 2,5-hexanedione from cellulose using ZrW as a catalyst, but the reaction time was too long (24 h) and the reaction required a high hydrogen pressure (5 MPa). Yaning Liu, Guangyi Li, Ning Li, et al. Integrated Conversion of Cellulose to High-Density Aviation Fuel[J]. Joule, 2019, 3(4), 1028-1036.) used Pd / C to catalyze the conversion of cellulose into 2,5-hexanedione. However, the solvent system was a mixture of concentrated hydrochloric acid and CH2Cl2, which was extremely acidic and highly toxic, and would corrode the reaction equipment.

[0009] Therefore, there is an urgent need to develop a low-cost, low-pollution, sustainable and efficient catalytic hydrogenation method for preparing 2,5-hexanedione using renewable biomass - cellulose as raw material. Summary of the invention

[0010] In view of the problems existing in the prior art, the present invention aims to provide a method for preparing ketone compounds by catalyzing the hydrogenation of cellulose using a Pd-TiO2 / C supported catalyst with mild reaction conditions, environmental friendliness and high catalytic efficiency, and to achieve catalytic hydrogenation reaction using crude hydrogen, thereby significantly reducing the cost of the catalytic reaction.

[0011] The purpose of the present invention is achieved through the following technical solutions: A method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst: using cellulose as a raw material, Pd-TiO2 / C as a catalyst, and a deionized water solution as a solvent, reacting for 2 to 6 hours at a hydrogen source gas pressure of 1 to 5 MPa and a temperature of 190 to 250°C composed of hydrogen and carbon monoxide to obtain ketone compounds mainly composed of 2,5-hexanedione; the Pd-TiO2 / C is prepared by loading palladium acetate and tetrabutyl titanate on an acidified activated carbon carrier through an impregnation and reduction method, wherein the loading amount of Pd is 0.5 to 5 wt.%, and the loading amount of TiO2 is 5 to 50 wt.%.

[0012] To further achieve the purpose of the present invention, preferably, the mass ratio of the cellulose to the Pd-TiO2 / C catalyst is 1:0.3~1:1.2; the mass ratio of the cellulose to deionized water is 1:10~1:20.

[0013] Preferably, the volume percentage of CO in the hydrogen source gas composed of hydrogen and carbon monoxide is between 0.5% and 60%.

[0014] Preferably, the Pd-TiO2 / C is prepared by the following method: ultrasonically dissolving a metal salt of palladium in an organic solvent, adding tetrabutyl titanate, adding an acidified activated carbon carrier after stirring, and excessively impregnating for 12 to 24 hours, rotary evaporation, drying, and reduction under a hydrogen atmosphere to obtain a Pd-TiO2 / C supported catalyst.

[0015] Preferably, the metal salt of palladium is one of chloride, nitrate, acetate or sulfate; the mass ratio of tetrabutyl titanate to the acidified activated carbon carrier is 0.2:1~1.8:1.

[0016] Preferably, the organic solvent is one of isopropanol, ethanol, acetone and methanol; the mass ratio of the palladium metal salt to the organic solvent is 0.01:20 to 0.05:20.

[0017] Preferably, the reduction under hydrogen atmosphere is carried out in a reduction furnace, the hydrogen partial pressure is 0.2-0.4 MPa, the reduction temperature is 200-400° C., and the reduction time is 3-6 h.

[0018] Preferably, the acidified activated carbon carrier is obtained by adding activated carbon to one of diluted hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid, stirring in an oil bath at 60-100° C. for 12-48 h, filtering, washing to neutrality and drying.

[0019] Preferably, the mass concentration of the diluted hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid is 30-50 wt.%.

[0020] Preferably, the ketone compound is an aliphatic ketone compound; the aliphatic ketone compound includes 2,5-hexanedione, 1-hydroxy-2-hexanone, 2-hydroxy-dihexanone, 2-methylcyclopentanone and 2-methyl-2-cyclopentanone ene.

[0021] Compared with the prior art, the present invention has the following characteristics: 1) The volume percentage of CO contained in the hydrogen source gas used in the present invention may be greater than 0.5%. Therefore, crude hydrogen with a high CO content can be used for cellulose catalytic hydrogenation reaction, thereby reducing the cost of cellulose catalytic reaction.

[0022] 2) Compared with the traditional method of preparing ketone compounds by catalytic hydrogenation of cellulose, the present invention uses water as a solvent, which is green and environmentally friendly and avoids corrosion damage to the reaction equipment.

[0023] 3) The catalyst used in the present invention is prepared by excessive impregnation, the preparation process is simple, and the raw materials are easily available.

[0024] 4) The present invention has mild reaction conditions for catalyzing the hydrogenation of cellulose to prepare ketone compounds and has high selectivity for 2,5-hexanedione. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the XRD spectrum of the 1Pd-10TiO2 / C catalyst in Example 11 of the present invention.

[0026] Figure 2 This is the nitrogen adsorption-desorption isotherm of the 1Pd-10TiO2 / C catalyst in Example 11 of the present invention.

[0027] Figure 3 This is the pore size distribution diagram of the 1Pd-10TiO2 / C catalyst in Example 11 of the present invention.

[0028] Figure 4 This is a SEM image of the activated carbon support after acidification in Example 11 of the present invention.

[0029] Figure 5 This is the SEM image of the 1Pd-10TiO2 / C catalyst in Example 11 of the present invention.

[0030] Figure 6 This is the TEM image of the 1Pd-10TiO2 / C catalyst in Example 11 of the present invention.

[0031] Figure 7 This is the EDS Mapping diagram of the 1Pd-10TiO2 / C catalyst in Example 11 of the present invention.

[0032] Figure 8 This is the Pd 3d spectrum in the XPS spectrum of the 1Pd-10TiO2 / C catalyst in Example 11 of the present invention.

[0033] Fig. 9 This is the Ti 2p spectrum in the XPS spectrum of the 1Pd-10TiO2 / C catalyst in Example 11 of the present invention.

[0034] Fig.10 NH3-TPD diagram of 1Pd-5TiO2 / C, 1Pd-10TiO2 / C, 1Pd-20TiO2 / C, and 1Pd-30TiO2 / C catalysts in Examples 1, 11, and 13 of the present invention.

[0035] Fig.11 This is the GC-MS-FID chart of preparing ketone compounds by catalytic hydrogenation of cellulose in Example 16 of the present invention.

[0036] Fig.12 This is the mass spectrum of preparing 2,5-hexanedione by catalytic hydrogenation of cellulose in Example 16 of the present invention. DETAILED DESCRIPTION

[0037] In order to better understand the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments, but the embodiments of the present invention are not limited thereto.

[0038] The present invention finds that a method for preparing ketone compounds mainly composed of 2,5-hexanedione by low-cost, low-pollution, sustainable and efficient catalytic hydrogenation with renewable biomass cellulose as raw material can be developed by using Pd-TiO2 / C as a catalyst. The method can realize catalytic hydrogenation reaction using crude hydrogen, thereby significantly reducing the cost of catalytic reaction. The method uses cellulose as raw material, Pd-TiO2 / C as a catalyst, and deionized water solution as a solvent. The pressure of hydrogen source gas composed of hydrogen and carbon monoxide is 1-5 MPa and the temperature is 190-250°C. The reaction is carried out for 2-6 hours to obtain ketone compounds mainly composed of 2,5-hexanedione; the Pd-TiO2 / C is prepared by loading palladium acetate and tetrabutyl titanate on an acidified activated carbon carrier through an impregnation and reduction method, wherein the loading amount of Pd is 0.5-5 wt.%, and the loading amount of TiO2 is 5-50 wt.%.

[0039] When the method of the present invention uses a catalyst to catalyze the hydrogenation of cellulose, when a hydrogen source gas is selected to provide hydrogen elements to the catalytic hydrogenation reaction, the hydrogen source gas may contain CO, and the volume percentage of CO based on the total volume of the hydrogen source gas may be greater than 0.5%. Compared with the Chinese invention patent CN114057554B, the present invention can select crude hydrogen as the hydrogen source gas, reduce the reaction cost of catalyzing the hydrogenation of cellulose to prepare ketone compounds, and use green solvent water as the reaction solvent to avoid damage to the reaction equipment caused by the use of liquid acid, and efficiently catalyze the hydrogenation of cellulose to prepare ketone compounds under relatively green and mild reaction conditions.

[0040] The present invention is a method for preparing ketone compounds by catalytic hydrogenation of cellulose, adopts a one-pot process, uses cellulose as a raw material, a Pd-TiO2 / C supported catalyst as a reaction catalyst, and water as a solvent, and sequentially adds the cellulose raw material and the catalyst into a high-pressure reactor, reacts for 2 to 6 hours at an atmosphere pressure of 1 to 5 MPa and a temperature of 190 to 250° C., and obtains ketone compounds mainly composed of 2,5-hexanedione. The present invention can obtain a cellulose conversion rate of 85.7% to 97.5%, a total ketone compound yield of 26.8% to 38.3%, wherein the yield of the main product 2,5-hexanedione is 10.0% to 20.1%, and the selectivity is 37.3% to 52.5%.

[0041] The ketone compounds of the present invention are aliphatic ketone compounds such as 2,5-hexanedione, 1-hydroxy-2-hexanone, 2-hydroxy-dihexanone, 2-methylcyclopentanone, and 2-methyl-2-cyclopentanone ene.

[0042] Example 1: Preparation of 1Pd-5TiO2 / C (hydrochloric acid) catalyst

[0043] The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support was prepared by hydrochloric acid acidification, and then the metal Pd was loaded by an excess impregnation method:

[0044] (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and place it in a 60°C oven to dry for 24 h to obtain the acidified activated carbon carrier.

[0045] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of isopropanol, and ultrasonically treat for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon carrier, add 1 g of the prepared acidified activated carbon carrier, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-5TiO2 / C (wherein the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%). The prepared 1Pd-5TiO2 / C catalyst was characterized by NH3-TPD to explore its acidity. The data from 50~700°C were selected, and the results are as follows: Fig.10The first curve is shown in the figure. The weak acid peak is concentrated at 100~200℃, and the medium-strong acid peak is concentrated at 200~400℃. It can be seen from the figure that when the doping amount of TiO2 is 5 wt.%, the catalyst mainly behaves as a weak acid with a small amount of medium-strong acid.

[0046] Example 2: Preparation of 1Pd-5TiO2 / C (sulfuric acid) catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support acidified with sulfuric acid was prepared, and then metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% sulfuric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0047] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of isopropanol, and ultrasonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon support, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-5TiO2 / C (where the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%).

[0048] Example 3: Preparation of 1Pd-5TiO2 / C (phosphoric acid) catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support was prepared by phosphoric acidization, and then the metal Pd was loaded by excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% phosphoric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0049] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of isopropanol, and ultrasonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon carrier, add 1 g of the prepared acidified activated carbon carrier, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h to obtain the target catalyst sample, which is recorded as 1Pd-5TiO2 / C (where the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%).

[0050] Example 4: Preparation of 1Pd-5TiO2 / C (nitric acid) catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support was prepared by nitric acid acidification, and then the metal Pd was loaded by excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% nitric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0051] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of isopropanol, and ultrasonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon support, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-5TiO2 / C (where the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%).

[0052] Example 5: Preparation of 1Pd-5TiO2 / C (acidification for 12 h) catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support was prepared by hydrochloric acid acidification, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 12 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and place it in a 60°C oven to dry for 24 h to obtain the acidified activated carbon carrier.

[0053] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of isopropanol, and ultrasonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon support, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-5TiO2 / C (where the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%).

[0054] Example 6: Preparation of 1Pd-5TiO2 / C (acidification for 48 h) catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support was prepared by hydrochloric acid acidification, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 48 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0055] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of isopropanol, and ultrasonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon support, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-5TiO2 / C (where the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%).

[0056] Example 7: Preparation of 1Pd-5TiO2 / C (acidification temperature 60°C) catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support was prepared by hydrochloric acid acidification, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 60°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0057] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of isopropanol, and ultrasonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon support, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-5TiO2 / C (where the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%).

[0058] Example 8: Preparation of 1Pd-5TiO2 / C (acidification temperature 100°C) catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support was prepared by hydrochloric acid acidification, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 100°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and place it in a 60°C oven to dry for 24 h to obtain the acidified activated carbon carrier.

[0059] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of isopropanol, and ultrasonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon support, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-5TiO2 / C (where the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%).

[0060] Example 9: Preparation of 1Pd-5TiO2 / C (Solvent: Ethanol) Catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support was prepared by hydrochloric acid acidification, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 100°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and place it in a 60°C oven to dry for 24 h to obtain the acidified activated carbon carrier.

[0061] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of ethanol, and ultrasonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon support, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C for 4 h in a hydrogen atmosphere to obtain the target catalyst sample, which is recorded as 1Pd-5TiO2 / C (where the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%).

[0062] Example 10: Preparation of 1Pd-5TiO2 / C (Solvent: Acetone) Catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-5TiO2 / C was achieved by a two-step method. First, an activated carbon support was prepared by hydrochloric acid acidification, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 100°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and place it in a 60°C oven to dry for 24 h to obtain the acidified activated carbon carrier.

[0063] (2) Preparation of 1Pd-5TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of acetone, and ultrasonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2219 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon support, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-5TiO2 / C (wherein the Pd loading is 1 wt.%, and the TiO2 loading is 5 wt.%).

[0064] Example 11: Preparation of 1Pd-10TiO2 / C Catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-10TiO2 / C was achieved by a two-step method. First, an acidified activated carbon support was prepared, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0065] (2) Preparation of 1Pd-10TiO2 / C catalyst: Weigh 0.0244 g of palladium acetate, add 20 mL of isopropanol and sonicate for 20 min. After the palladium acetate is completely dissolved, add 0.4775 g of tetrabutyl titanate, stir for 10 min, then add 1 g of the prepared acidified activated carbon carrier, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40 °C. After the solvent is completely evaporated, place it in a 60 °C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300 °C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-10TiO2 / C (where the Pd loading is 1 wt.%, and the TiO2 loading is 10 wt.%).

[0066] The prepared 1Pd-10TiO2 / C catalyst was characterized by X-ray diffraction to explore its crystal structure. Figure 1 As shown in the figure, the 1Pd-10TiO2 / C catalyst shows diffraction peaks of TiO2 at 2x diffraction angles of 31.0, 39.7, 42.3 and 49.1°, and its characteristic peaks correspond to the (211), (112), (221) and (312) crystal planes of brookite TiO2 (PDF#72-0100). This indicates that TiO2 is successfully loaded on the carrier surface. The characteristic diffraction peaks of Pd are not clearly observed because its loading content is low (1 wt.%) and Pd is well dispersed on the surface of the catalyst.

[0067] The prepared 1Pd-10TiO2 / C catalyst was characterized by N2 physical adsorption and desorption to explore its pore structure. Figure 2 , Figure 3 The adsorption isotherms of the catalysts all belong to type IV isotherms, and an obvious H4 type hysteresis loop can be observed in the medium relative pressure range (P / P0=0.4~1.0). Combined with the pore size distribution diagram, it can be seen that the main pore structure of the catalyst is mesoporous and contains a small amount of microporous surface, which is conducive to the mass transfer of cellulose molecules.

[0068] The prepared activated carbon support and 1Pd-10TiO2 / C catalyst were characterized by SEM to explore their morphological characteristics and microstructure. Figure 4 , Figure 5 As shown by Figure 4 It can be seen that the activated carbon carrier after acidification is mainly in the form of flakes with wrinkles on the surface. Figure 5 It can be seen that due to the loading of Pd and TiO2, a series of nano-spherical particles are formed on the rough surface of the 1Pd-10TiO2 / C catalyst. TEM characterization and EDS Mapping analysis of the 1Pd-10TiO2 / C catalyst are shown in the following results. Figure 6 , Figure 7 As shown, the high-resolution transmission electron microscopy (HRTEM) image of 1Pd-10TiO2 / C ( Figure 6 ) shows that its characteristic interplanar spacing is 0.19 nm and 0.23 nm, corresponding to the (200) and (111) planes of Pd nanoparticles, respectively. There are also TiO2 with interplanar spacings of 0.20 nm, 0.22 nm, and 0.25 nm, corresponding to the (212), (112), and (102) planes of Brookite TiO2, respectively, which is consistent with the XRD test data. Figure 7 EDS Mapping data show that TiO2 is evenly dispersed in the system, and the nanoclusters aggregated by Pd can be well dispersed on the surface of the carrier, and the metal catalytic active sites are well dispersed.

[0069] In order to explore the existence form of each component in the 1Pd-10TiO2 / C catalyst, the valence state of the metal and the synergistic effect of each component, the catalyst was characterized by XPS. The results are as follows: Figure 8 , Fig. 9 shown. Figure 8 is the Pd 3d spectrum of 1Pd-10TiO2 / C catalyst, Figure 8 It can be seen that the Pd element in the catalyst is mainly in the form of Pd 0 and Pd 2+ There are two forms, accounting for 75.4% and 24.5% respectively. Fig. 9 The Ti 2p spectrum in the catalyst. It can be seen from the figure that the Ti 2p in 1Pd-10TiO2 / C 1 / 2 and Ti 2p 3 / 2 The binding energies of the TiO2 are 465.1 and 459.4 eV, respectively, which are higher than the corresponding binding energies of pure TiO2 (464.2 and 458.3 eV), which may be caused by oxygen vacancy defects during the high pyrolysis process.

[0070] The prepared 1Pd-10TiO2 / C catalyst was characterized by NH3-TPD to explore its acidity. The data at 50~700℃ were selected. The results are as follows: Fig.10 As shown in the second curve. The weak acid peak is concentrated at 100~200℃, and the medium-strong acid peak is concentrated at 200~400℃. When the doping amount of TiO2 is 5 wt.%, the catalyst mainly exhibits weak acidity. After further increasing the doping amount of TiO2, the change of the catalyst acid site can be observed. After loading 10 wt.% of TiO2, the total acid site increases, and the peak intensity of the weak acid site is significantly enhanced. This is because the incorporation of TiO2 provides Lewis acid sites, which changes the acidity of the catalyst.

[0071] Example 12: Preparation of 1Pd-20TiO2 / C Catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-20TiO2 / C was achieved by a two-step method. First, an acidified activated carbon support was prepared, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0072] (2) Preparation of 1Pd-20TiO2 / C catalyst: Weigh 0.0276 g of palladium acetate, add 20 mL of isopropanol and sonicate for 20 min. After the palladium acetate is completely dissolved, add 1.0788 g of tetrabutyl titanate, stir for 10 min, then add 1 g of the prepared acidified activated carbon carrier and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40 °C. After the solvent is completely evaporated, place it in a 60 °C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300 °C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-20TiO2 / C (wherein the Pd loading is 1 wt.%, and the TiO2 loading is 20 wt.%). The prepared 1Pd-20TiO2 / C catalyst was characterized by NH3-TPD to explore its acidity. The data from 50~700 °C were selected, and the results are as follows: Fig.10As shown in the third curve. The weak acid peak is concentrated at 100~200℃, and the medium-strong acid peak is concentrated at 200~400℃. It can be seen from the figure that when the TiO2 doping amount is 20 wt.%, compared with the TiO2 loaded with 10 wt.%, its total acid sites increase, and the peak intensity of the medium-strong acid sites is significantly enhanced. This is because the further increase in the TiO2 loading increases the Lewis acid sites and changes the acidity of the catalyst.

[0073] Example 13: Preparation of 1Pd-30TiO2 / C Catalyst The preparation of carbon-supported palladium-based catalyst 1Pd-30TiO2 / C was achieved by a two-step method. First, an acidified activated carbon support was prepared, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0074] (2) Preparation of 1Pd-30TiO2 / C catalyst: Weigh 0.0315 g of palladium acetate, add 20 mL of isopropanol and sonicate for 20 min. After the palladium acetate is completely dissolved, add 1.8527 g of tetrabutyl titanate, stir for 10 min, then add 1 g of the prepared acidified activated carbon carrier and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40 °C. After the solvent is completely evaporated, place it in a 60 °C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300 °C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 1Pd-30TiO2 / C (wherein the Pd loading is 1 wt.%, and the TiO2 loading is 30 wt.%). The prepared 1Pd-30TiO2 / C catalyst was characterized by NH3-TPD to explore its acidity. The data from 50~700 °C were selected, and the results are as follows: Fig.10 As shown in the fourth curve in the figure. The weak acid peak is concentrated at 100~200℃, and the medium-strong acid peak is concentrated at 200~400℃. It can be seen from the figure that when the TiO2 doping amount is 30 wt.%, compared with the TiO2 loaded with 10 wt.%, the total acid sites increase, and the peak intensity of the weak acid sites and medium-strong acid sites is significantly enhanced. This is because the further increase in the TiO2 loading increases the Lewis acid sites and changes the acidity of the catalyst.

[0075] Example 14: Preparation of 0.5Pd-10TiO2 / C Catalyst The preparation of carbon-supported palladium-based catalyst 0.5Pd-10TiO2 / C was achieved by a two-step method. First, an acidified activated carbon support was prepared, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0076] (2) Preparation of 0.5Pd-10TiO2 / C catalyst: Weigh 0.0122 g of palladium acetate, add 20 mL of isopropanol and sonicate for 20 min. After the palladium acetate is completely dissolved, add 0.2394 g of tetrabutyl titanate, stir for 10 min, add 1 g of the prepared acidified activated carbon carrier, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40°C. After the solvent is completely evaporated, place it in a 60°C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300°C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 0.5Pd-10TiO2 / C (where the Pd loading is 0.5wt.%, and the TiO2 loading is 10 wt.%).

[0077] Example 15: Preparation of 2Pd-10TiO2 / C Catalyst The preparation of metal oxide-doped carbon-supported palladium-based catalyst 2Pd-10TiO2 / C was achieved by a two-step method. First, an acidified activated carbon support was prepared, and then the metal Pd was loaded by an excess impregnation method: (1) Preparation of acidified activated carbon carrier: Weigh 1 g of activated carbon, then add 10 mL of 37 wt.% hydrochloric acid and 10 mL of deionized water, place it in an oil bath, and stir at 80°C for 24 h. After completion, filter it, wash it with deionized water until the filtrate is neutral when tested with pH paper, and dry it in a 60°C oven for 24 h to obtain the acidified activated carbon carrier.

[0078] (2) Preparation of 2Pd-10TiO2 / C catalyst: Weigh 0.0489 g of palladium acetate, add 20 mL of isopropanol and sonicate for 20 min. After the palladium acetate is completely dissolved, add 2.0812 g of tetrabutyl titanate, stir for 10 min, then add 1 g of the prepared acidified activated carbon carrier, and stir at room temperature for 24 h. Transfer the solution to a pear-shaped bottle and perform rotary evaporation at 40 °C. After the solvent is completely evaporated, place it in a 60 °C oven and dry it for 24 h. After grinding it, use a reduction furnace to reduce it at 300 °C in a hydrogen atmosphere for 4 h, and finally obtain the target catalyst sample recorded as 2Pd-10TiO2 / C (where the Pd loading is 2 wt.%, and the TiO2 loading is 10 wt.%).

[0079] Example 16: Preparation of ketone compounds by 1Pd-10TiO2 / C catalytic cellulose hydrogenation 100 mg of cellulose, 50 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to the autoclave. The autoclave was sealed, and the gas in the autoclave was replaced with the reaction gas for 5 times. The hydrogen source gas required for the reaction (non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the autoclave was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction 3 times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven for drying and the reaction conversion rate was calculated.

[0080] The analysis was performed using a gas chromatography-mass spectrometer (HP-INNOWAX chromatograph: 30 m×0.25 mm×0.25 μm) with a column flow rate of 2 mL min -1 , split ratio 4:1. Heating program: 50℃ for 1 min, 10℃ min -1 The heating rate was raised to 280°C and maintained for 35 min, and the liquid phase product was qualitatively analyzed and quantitatively calculated. As shown in the GC-MS-FID diagram of catalytic cellulose hydrogenation to prepare ketone compounds in Example 16 of the present invention ( Fig.11 ) As shown in Figure 2, GC-MS analysis shows that there are five main ketone compounds, namely 2,5-hexanedione, 1-hydroxy-2-hexanone, 2-hydroxy-dihexanone, 2-methylcyclopentanone and 2-methyl-2-cyclopentanone ene. The mass spectrum of the main product 2,5-hexanedione is shown in Figure 2 Fig.12 As shown, according to the mass spectrum, it can be seen that the main product is indeed 2,5-hexanedione.

[0081] Table 1 Distribution and yield of ketone products obtained by catalytic cellulose hydrogenation

[0082] The cellulose conversion rate is C c , total ketone compound yield Y t , 2,5-hexanedione yield Y hd , whose selectivity is S hd , calculated according to formulas (1-1) to (1-4), where M c Represents the mass of substrate cellulose, M g is the mass of catalyst added, M re is the mass of solid filtered after the reaction, M t is the mass of ketone products, M hd is the mass of the main product 2,5-hexanedione.

[0083] (1-1

[0084] (1-2)

[0085] (1-3)

[0086] (1-4)

[0087] The GC-FID diagram of the product is as follows: Fig.11 The corresponding products and their retention times are shown in Table 1, wherein the main product 2,5-hexanedione has the strongest peak signal. The mass spectrum of the main product is shown in Fig.12 As shown, the generation of 2,5-hexanedione was further confirmed by comparing the particle distribution and relative abundance of particles with different mass-to-charge ratios.

[0088] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 96.3%, the yield of total ketone compounds reaches 38.3%, among which the yield of the main product 2,5-hexanedione is 20.1% and the selectivity is 52.5%.

[0089] Example 17: Preparation of ketone compounds by 1Pd-5TiO2 / C catalyzed cellulose hydrogenation

[0090] The difference between this embodiment and embodiment 16 is that:

[0091] 100 mg of cellulose, 50 mg of 1Pd-5TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas for 3 times. The hydrogen source gas required for the reaction (non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction 3 times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven to dry and the reaction conversion rate was calculated.

[0092] The calculation results show that under the catalytic action of 1Pd-5TiO2 / C, the conversion rate of cellulose is 96.7%, the yield of total ketone compounds reaches 26.8%, among which the yield of the main product 2,5-hexanedione is 10.0%, and the selectivity is 37.3%.

[0093] Example 18: Preparation of ketone compounds by 1Pd-20TiO2 / C catalytic cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 50 mg of 1Pd-20TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas 4 times. The hydrogen source gas required for the reaction (non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction 3 times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven for drying and the reaction conversion rate was calculated.

[0094] The calculation results show that under the catalytic action of 1Pd-20TiO2 / C, the conversion rate of cellulose is 97.2%, the yield of total ketone compounds reaches 31.7%, among which the yield of the main product 2,5-hexanedione is 13.9% and the selectivity is 43.8%.

[0095] Example 19: Preparation of ketone compounds by 1Pd-30TiO2 / C catalyzed cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 50 mg of 1Pd-30TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas for 5 times. The hydrogen source gas required for the reaction (a non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction 3 times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven for drying and the reaction conversion rate was calculated.

[0096] The calculation results show that under the catalytic action of 1Pd-30TiO2 / C, the conversion rate of cellulose is 97.5%, the yield of total ketone compounds reaches 30.6%, among which the yield of the main product 2,5-hexanedione is 12.9% and the selectivity is 42.2%.

[0097] Example 20: Preparation of ketone compounds by hydrogenation of cellulose catalyzed by 0.5Pd-10TiO2 / C

[0098] The difference between this embodiment and embodiment 16 is that:

[0099] 100 mg of cellulose, 50 mg of 0.5Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas three times. The hydrogen source gas required for the reaction (a non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction three times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven to dry and the reaction conversion rate was calculated.

[0100] The calculation results show that under the catalytic action of 0.5Pd-10TiO2 / C, the conversion rate of cellulose is 96.3%, the yield of total ketone compounds reaches 31.4%, among which the yield of the main product 2,5-hexanedione is 14.2% and the selectivity is 45.2%.

[0101] Example 21: Preparation of ketone compounds by hydrogenation of cellulose catalyzed by 2Pd-10TiO2 / C The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 50 mg of 2Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas 4 times. The hydrogen source gas required for the reaction (non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction 3 times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven for drying and the reaction conversion rate was calculated.

[0102] The calculation results show that under the catalytic action of 2Pd-10TiO2 / C, the conversion rate of cellulose is 97.1%, the yield of total ketone compounds reaches 30.5%, among which the yield of the main product 2,5-hexanedione is 13.4% and the selectivity is 43.9%.

[0103] Example 22: Preparation of ketone compounds by 1Pd-10TiO2 / C catalyzed cellulose hydrogenation

[0104] The difference between this embodiment and embodiment 16 is that:

[0105] 100 mg of cellulose, 100 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas 4 times. The hydrogen source gas required for the reaction (non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction 3 times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven for drying and the reaction conversion rate was calculated.

[0106] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 85.7%, the yield of total ketone compounds reaches 24.3%, among which the yield of the main product 2,5-hexanedione is 13.9% and the selectivity is 57.2%.

[0107] Example 23: Preparation of ketone compounds by 1Pd-10TiO2 / C catalyzed cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 30 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas three times. The hydrogen source gas required for the reaction (a non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction three times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven to dry and the reaction conversion rate was calculated.

[0108] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 94.4%, the yield of total ketone compounds reaches 29.9%, among which the yield of the main product 2,5-hexanedione is 15.2% and the selectivity is 50.8%.

[0109] Example 24: Preparation of ketone compounds by 1Pd-10TiO2 / C catalytic hydrogenation of cellulose The difference between this embodiment and embodiment 16 is that:

[0110] 100 mg of cellulose, 100 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas three times. The hydrogen source gas required for the reaction (a non-pure hydrogen mixture with a CO content of 50%) was filled in at 2 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction three times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven to dry and the reaction conversion rate was calculated.

[0111] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 96.7%, the yield of total ketone compounds reaches 30.2%, among which the yield of the main product 2,5-hexanedione is 13.2% and the selectivity is 43.7%.

[0112] Example 25: Preparation of ketone compounds by 1Pd-10TiO2 / C catalytic cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 100 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas three times. The hydrogen source gas required for the reaction (a non-pure hydrogen mixture with a CO content of 50%) was filled in at 4 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction three times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven to dry and the reaction conversion rate was calculated.

[0113] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 97.3%, the yield of total ketone compounds reaches 27.9%, among which the yield of the main product 2,5-hexanedione is 13.5% and the selectivity is 48.4%.

[0114] Example 26: Preparation of ketone compounds by 1Pd-10TiO2 / C catalytic cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 100 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas for 5 times. The hydrogen source gas required for the reaction (non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 210°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction 3 times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven for drying and the reaction conversion rate was calculated.

[0115] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 94.3%, the yield of total ketone compounds reaches 34.1%, among which the yield of the main product 2,5-hexanedione is 16.1% and the selectivity is 47.2%.

[0116] Example 27: Preparation of ketone compounds by 1Pd-10TiO2 / C catalyzed cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 100 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas 4 times. The hydrogen source gas required for the reaction (non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 250°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction 3 times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven to dry and the reaction conversion rate was calculated.

[0117] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 95.8%, the yield of total ketone compounds reaches 24.0%, among which the yield of the main product 2,5-hexanedione is 13.4% and the selectivity is 55.8%.

[0118] Example 28: Preparation of ketone compounds by 1Pd-10TiO2 / C catalytic cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 100 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas three times. The hydrogen source gas required for the reaction (a non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 2 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction three times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven for drying and the reaction conversion rate was calculated.

[0119] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 93.2%, the yield of total ketone compounds reaches 29.2%, among which the yield of the main product 2,5-hexanedione is 12.6%, and the selectivity is 43.2%.

[0120] Example 29: Preparation of ketone compounds by 1Pd-10TiO2 / C catalyzed cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 100 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas three times. The hydrogen source gas required for the reaction (non-pure hydrogen mixture with a CO content of 50%) was filled in at 3 MPa. The reaction was carried out at 230°C for 4 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and NaCl was added to the filtered reaction liquid until it became a saturated NaCl solution. The reaction liquid was extracted with ethyl acetate. After extraction three times, internal standard dimethyl phthalate was added and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven to dry and the reaction conversion rate was calculated.

[0121] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 96.5%, the yield of total ketone compounds reaches 25.2%, among which the yield of the main product 2,5-hexanedione is 14.7% and the selectivity is 58.3%.

[0122] Example 30: Preparation of ketone compounds by 1Pd-10TiO2 / C catalytic cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 100 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas three times. The hydrogen source gas required for the reaction (non-pure hydrogen mixed gas with a CO content of 0.5%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and the internal standard dimethyl phthalate was added to the filtered reaction liquid and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven to dry and the reaction conversion rate was calculated.

[0123] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 94.3%, the yield of total ketone compounds reaches 21.8%, among which the yield of the main product 2,5-hexanedione is 12.7% and the selectivity is 58.3%.

[0124] Example 31: Preparation of ketone compounds by 1Pd-10TiO2 / C catalytic cellulose hydrogenation The difference between this embodiment and embodiment 16 is that: 100 mg of cellulose, 100 mg of 1Pd-10TiO2 / C catalyst, and 20 mL of deionized water were weighed and added to a high-pressure reactor. The reactor was sealed, and the gas in the reactor was replaced with the reaction gas three times. The hydrogen source gas required for the reaction (a non-pure hydrogen mixture with a CO content of 60%) was filled in at 3 MPa. The reaction was carried out at 230°C for 3 h. After the reaction was completed and cooled to room temperature, the reactor was opened, the reaction liquid was taken out and filtered, and the internal standard dimethyl phthalate was added to the filtered reaction liquid and the volume was fixed to 25 mL. 1 mL of the reaction liquid was taken, filtered through a 0.22 μm filter membrane, transferred to a sample bottle, and analyzed by GC-MS-FID. The filtered residue was placed in an oven to dry and the reaction conversion rate was calculated.

[0125] The calculation results show that under the catalytic action of 1Pd-10TiO2 / C, the conversion rate of cellulose is 95.9%, the yield of total ketone compounds reaches 28.9%, among which the yield of the main product 2,5-hexanedione is 13.9% and the selectivity is 48.1%.

[0126] It can be seen from the above embodiments that the present invention adopts a method for preparing ketone compounds by catalyzing cellulose hydrogenation with a Pd-TiO2 / C catalyst. Under the conditions of a hydrogen source gas pressure of 1-5 MPa containing hydrogen and carbon monoxide and a CO volume percentage between 0.5% and 60%, a reaction temperature of 190-250°C, and a reaction time of 2-6 h, the cellulose conversion rate reaches 85.7%-97.5%, and the total ketone compound yield reaches 26.8-38.3%, wherein the yield of the main product 2,5-hexanedione reaches 10.0-20.1%, and the selectivity reaches 37.3%-52.5%.

[0127] The method for preparing ketone compounds by catalyzing cellulose hydrogenation using a Pd-TiO2 / C catalyst adopted in the present invention can utilize crude hydrogen containing CO for hydrogenation reaction, has the advantages of low reaction cost, renewable raw materials, environmental friendliness, mild conditions, high selectivity, etc., and provides an effective way to prepare ketone compounds from biomass.

[0128] The implementation methods of the present invention are not limited to the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst, characterized in that: Cellulose is used as raw material, Pd-TiO2 / C is used as catalyst, and deionized water solution is used as solvent. The reaction is carried out for 2 to 6 hours at a hydrogen source gas pressure of 1 to 5 MPa and a temperature of 190 to 250°C, so as to obtain ketone compounds mainly composed of 2,5-hexanedione. The Pd-TiO2 / C is prepared by loading palladium acetate and tetrabutyl titanate on an acidified activated carbon carrier through an impregnation and reduction method, wherein the loading amount of Pd is 0.5 to 5 wt.%, and the loading amount of TiO2 is 5 to 50 wt.%.

2. The method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst according to claim 1, characterized in that: The mass ratio of the cellulose to the Pd-TiO2 / C catalyst is 1:0.3-1:1.2; the mass ratio of the cellulose to deionized water is 1:10-1:

20.

3. The method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst according to claim 1, characterized in that: The volume percentage of CO in the hydrogen source gas composed of hydrogen and carbon monoxide is between 0.5% and 60%.

4. The method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst according to claim 1, characterized in that: The Pd-TiO2 / C is prepared by the following method: ultrasonically dissolving a metal salt of palladium in an organic solvent, adding tetrabutyl titanate, stirring, adding an acidified activated carbon carrier, excessively impregnating for 12 to 24 hours, rotary evaporation, drying, and reducing under a hydrogen atmosphere to obtain a Pd-TiO2 / C supported catalyst.

5. The method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst according to claim 4, characterized in that: The metal salt of palladium is one of chloride, nitrate, acetate or sulfate; the mass ratio of tetrabutyl titanate to the acidified activated carbon carrier is 0.2:1-1.8:

1.

6. The method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst according to claim 4, characterized in that: The organic solvent is one of isopropanol, ethanol, acetone and methanol; the mass ratio of the palladium metal salt to the organic solvent is 0.01:20-0.05:

20.

7. The method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst according to claim 4, characterized in that: The reduction under hydrogen atmosphere is carried out in a reduction furnace, the hydrogen partial pressure is 0.2-0.4 MPa, the reduction temperature is 200-400° C., and the reduction time is 3-6 h.

8. The method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst according to claim 4, characterized in that: The acidified activated carbon carrier is obtained by adding activated carbon to one of diluted hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid, stirring in an oil bath at 60-100° C. for 12-48 hours, filtering, washing to neutrality and drying.

9. The method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst according to claim 8, characterized in that: The mass concentration of the diluted hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid is 30-50 wt.%.

10. The method for preparing ketone compounds by hydrogenating cellulose using a Pd-TiO2 / C supported catalyst according to claim 1, characterized in that: The ketone compounds are aliphatic ketone compounds; the aliphatic ketone compounds include 2,5-hexanedione, 1-hydroxy-2-hexanone, 2-hydroxy-dihexanone, 2-methylcyclopentanone and 2-methyl-2-cyclopentanone ene.

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