Nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst, method for preparing and use thereof

Abstract

The application discloses a nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst and a preparation method and application thereof. The preparation method of the catalyst is as follows: (1) preparing a nitrogen-doped titanium dioxide carrier; (2) preparing an aqueous solution containing a copper compound, adding the nitrogen-doped titanium dioxide, and then drying and calcining after heating and stirring to obtain Cu / TiO2-xN; (3) preparing a mixed aqueous solution containing a palladium compound and a dispersing agent, adding Cu / TiO2-xN after heating and stirring, and continuing to stir for 3-5 hours; adjusting the pH value of the solution to 9.0-12.0, and continuing to stir for 0.5-2 hours; adding a liquid-phase reducing agent for reduction; and then filtering, washing and vacuum drying to obtain the nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst. The application provides application of the nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst in selective catalytic hydrogenation of benzophenone to synthesize benzhydrol, and the catalyst has good catalytic activity, target product selectivity and stability.

Description

Technical Field

[0001] This invention relates to a nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst, its preparation method, and its application in the selective catalytic hydrogenation of benzophenone to dibenzyl alcohol, belonging to the field of chemical synthesis technology. Background Technology

[0002] Diphenylethanol, also known as α-phenylbenzyl alcohol, is an important organic intermediate widely used in pharmaceuticals, agrochemicals, and fragrances. For example, it is used in the synthesis of antihistamines including diphenhydramine, benzodiazepine, cycladine, and diphenylalanine. It is also used in the synthesis of drugs such as benztropine, modafinil, cinnarizine, atraquat, and cephalosporin antibiotics. In the perfume industry, it is used as a fixative.

[0003] Currently, benzyl alcohol is mainly prepared by the reduction of benzophenone, including three processes:

[0004] (1) Zinc powder reduction method: Zinc powder and alkaline solution are mixed and used. This method requires a large amount of zinc powder. After the reaction, a large amount of waste liquid containing heavy metals is generated. The product has poor purity, is difficult to separate, has a complicated process, high production cost, serious environmental pollution, and great damage to reaction equipment. It has been gradually phased out.

[0005] (2) Sodium borohydride reduction method: This method uses sodium borohydride, a strong reducing agent, for chemical reduction. It requires a large amount of sodium borohydride, has a low yield, and produces borate esters as a byproduct during the reaction. The production process generates large amounts of wastewater and waste residue, which does not meet the requirements of current green chemistry processes.

[0006] (3) Catalytic hydrogenation: A catalytic chemical reduction method using hydrogen as a reducing agent. This method not only produces products with high purity, but also has the advantages of low emissions, low energy consumption, and high product quality, which conforms to today's green and environmentally friendly production processes. However, when benzophenone is hydrogenated to synthesize diphenylmethanol, over-hydrogenation often occurs, producing diphenylmethane. The catalytic hydrogenation process for synthesizing diphenylmethanol has not been industrially feasible.

[0007] Therefore, it is of great significance to explore a highly active, highly selective, and highly stable selective hydrogenation catalyst for benzophenone. Summary of the Invention

[0008] The purpose of this invention is to provide a bimetallic liquid-phase hydrogenation catalyst with good catalytic activity, target product selectivity and stability, its preparation method and its application in the selective catalytic hydrogenation of benzophenone to dibenzyl alcohol.

[0009] The technical solutions adopted by the present invention to achieve the above-mentioned objectives are described below.

[0010] On the one hand, the present invention provides a method for preparing a nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst, the specific steps of which are as follows:

[0011] (1) Preparation of nitrogen-doped titanium dioxide support: Dissolve nitrogen-containing organic matter in a mixed solution composed of deionized water, anhydrous ethanol and concentrated nitric acid, and stir evenly at room temperature to obtain solution A; then take an appropriate amount of titanium-containing organic matter and dissolve it in anhydrous ethanol, and stir evenly at room temperature to obtain solution B; then, while stirring, slowly add solution A to solution B, and continue stirring for 2-4 hours until a transparent sol is formed, and let it stand at room temperature to air dry until a transparent gel is formed; place this gel in a vacuum drying oven and dry it at 60-90℃ for 8-12 hours; then, grind it with an agate mortar to obtain dry gel powder; finally, place the dry gel powder in a muffle furnace and calcine it at 300-500℃ for 2-4 hours, and cool it to room temperature to obtain nitrogen-doped titanium dioxide support, which is denoted as TiO2-xN, where x represents the molar percentage of doped nitrogen element in titanium element, x = 1%-5%, and this x is calculated according to the feeding ratio;

[0012] (2) Weigh a certain amount of copper-containing compound and dissolve it in an appropriate amount of deionized water. Stir at room temperature to obtain a uniform solution. Add the nitrogen-doped titanium dioxide obtained in step (1) and stir at 50-70℃ for 5-8h. Place the obtained product in a vacuum drying oven and dry at 80-110℃ for 8-12h. Place the obtained solid in a muffle furnace and calcine at 300-500℃ for 2-4h to obtain Cu / TiO2-xN.

[0013] (3) Take a certain amount of palladium-containing compound and add it to an appropriate amount of deionized water. Add an appropriate amount of dispersant, heat to 50-70℃ and keep stirring for 1-3 hours. Add Cu / TiO2-xN obtained in step (2) and continue stirring for 3-5 hours. Slowly add an aqueous solution of alkaline substance to the above suspension, adjust the pH value of the solution to 9.0-12.0, and continue stirring for 0.5-2 hours. Slowly add liquid phase reducing agent to the obtained suspension, keep the temperature and reduce for 0.5-2 hours. After the reduction is completed, turn off the heating and stir at room temperature for 0.5-1 hours. Filter the above suspension and wash it with deionized water until the pH of the filtrate is neutral. The obtained sample is dried under vacuum to obtain a nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst, wherein the loading of Cu is 2wt%-8wt% and the loading of Pd is 1wt%-5wt%. The loading of both metals is calculated according to the feeding ratio, where Cu loading = mass of Cu / (mass of Pd + mass of Cu + mass of TiO2-xN) × 100%, and Pd loading = mass of Pd / (mass of Pd + mass of Cu + mass of TiO2-xN).

[0014] Further, in step (1), the nitrogen-containing organic compound is at least one of urea, alanine, and melamine.

[0015] Further, in step (1), the titanium-containing organic compound is at least one of tetraethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate.

[0016] Further, in step (2), the copper-containing compound is at least one of copper chloride, copper nitrate, and copper sulfate.

[0017] Further, in step (3), the palladium-containing compound solution is at least one of sodium tetrachloropalladium, palladium nitrate, and dichlorotetraamminepalladium.

[0018] Further, in step (3), the dispersant is at least one selected from polyethylene glycol, polyvinylpyrrolidone, ethylenediamine, and glucose. The amount of the dispersant used is 5% of the mass of the palladium-containing compound, the copper-containing compound, and TiO2-xN.

[0019] Furthermore, in step (3), the alkaline substance is sodium hydroxide, potassium hydroxide, or ammonia.

[0020] Further, in step (3), the liquid-phase reducing agent is an aqueous solution of hydrazine hydrate, formic acid, formaldehyde, or sodium borohydride. Even further, the ratio of the amount of the liquid-phase reducing agent to the total amount of palladium- and copper-containing compounds is 5-15:1, preferably 10:1.

[0021] Furthermore, in step (3), the vacuum drying temperature is 80-110℃ and the vacuum drying time is 8-12h.

[0022] Furthermore, x = 5%, and the loadings of Pd and Cu are 3% and 5%, respectively.

[0023] In a second aspect, the present invention provides a nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst prepared according to the preparation method described in the first aspect.

[0024] Thirdly, the present invention provides the application of the nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst in the selective catalytic hydrogenation of benzophenone to dibenzyl alcohol.

[0025] The selective catalytic hydrogenation of benzophenone to diphenylmethanol is specifically implemented according to the following steps: Benzophenone, an organic solvent, sodium hydroxide, and a nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst are added sequentially to a reaction vessel. The organic solvent is methanol, and the mass ratio of the nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst to benzophenone is ≥0.02. The air in the reaction vessel is replaced with hydrogen, and hydrogen is introduced. The reaction is carried out at 0.5-3 MPa and 60-90℃ for 1-4 hours. The resulting reaction solution is filtered to remove the catalyst, and the filtrate is distilled or purified to obtain diphenylmethanol.

[0026] Furthermore, the mass ratio of the amount of sodium hydroxide to the amount of nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst is 0.2.

[0027] Furthermore, the feed ratio of benzophenone, organic solvent, sodium hydroxide, and nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst is 30g:200mL:0.12g:0.6g.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1) The nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst prepared in this invention introduces defect sites and nitrogen species in the nitrogen doping process during the preparation of the nitrogen-doped titanium dioxide support, which is beneficial to better disperse and anchor the palladium-copper bimetallic. Therefore, the nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst has good stability in hydrogenation reaction and can be reused multiple times.

[0030] 2) The nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst prepared in this invention utilizes copper to modify palladium, which reduces the active sites that promote the hydrogenolysis of benzyl methanol and can significantly suppress the side reaction of benzyl methanol to benzylmethane, thus improving the selectivity of benzyl methanol. At the same time, the synergistic effect between palladium and copper can further improve the hydrogenation activity of the catalyst.

[0031] 3) The nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst prepared in this invention incorporates a dispersant during the palladium loading process, which enhances the interaction between palladium and copper, allowing the reduced active component palladium to be uniformly dispersed on the copper surface, resulting in stronger intermetallic synergy and improved catalyst activity.

[0032] 4) The method for selective catalytic hydrogenation of benzophenone to synthesize benzyl alcohol described in this invention adds an appropriate amount of sodium hydroxide alkaline auxiliary, which can further avoid excessive hydrogenation of benzyl alcohol, which is conducive to obtaining high yield of benzyl alcohol and improves the selectivity of benzyl alcohol. Attached Figure Description

[0033] Figure 1 This is the XRD pattern of the 3% Pd-5% Cu / TiO2-5% N catalyst prepared in Example 6;

[0034] Figure 2 This is a TEM image of the 3%Pd-5%Cu / TiO2-5%N catalyst prepared in Example 6;

[0035] Figure 3 This is the elemental analysis diagram of the 3%Pd-5%Cu / TiO2-5%N catalyst prepared in Example 6. Detailed Implementation

[0036] The technical solution of the present invention will be described in more detail below with reference to the embodiments. The scope of protection of the present invention is not limited to the specific embodiments described below.

[0037] Example 1

[0038] (1) Dissolve 0.1425g of alanine in a mixed solution consisting of 5mL deionized water, 25mL anhydrous ethanol, and 2mL concentrated nitric acid, and stir at room temperature for 20min to obtain solution A; dissolve 5mL of tetraethyl titanate in 25mL anhydrous ethanol, and stir at room temperature for 30min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 3h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 90℃ for 8h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400℃ for 3h, and cool it to room temperature to obtain TiO2-5%N.

[0039] (2) Weigh 0.1639g of copper sulfate and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 6h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 500℃ for 2h to obtain 3%Cu / TiO2-5%N.

[0040] (3) Weigh 0.3015g sodium tetrachloropalladium and dissolve it in 50mL of deionized water. Add 0.1220g polyethylene glycol, heat to 70℃ and stir for 1h. Add the 3% Cu / TiO2-5%N prepared in step (2), and continue to heat and stir for 3h. Add 1mol / L sodium hydroxide solution to adjust the pH of the mixture to 9, and continue to heat and stir for 1h. Slowly add 2.0mL of 40wt% sodium borohydride solution to the obtained suspension, maintain the temperature for 1h to reduce, then turn off the heating and stir at room temperature for 1h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven at 110℃ and dry for 8h to obtain 5%Pd-3%Cu / TiO2-5%N.

[0041] Example 2

[0042] (1) Dissolve 0.0202 g of melamine in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetraethyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 20 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 2 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 450 °C for 2 h, and cool it to room temperature to obtain TiO2-3%N.

[0043] (2) Weigh 0.3938g of copper nitrate and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-3%N obtained in step (1), stir at 50℃ for 8h, put the product into a vacuum drying oven and dry at 100℃ for 10h, and calcine in a muffle furnace at 400℃ for 3h to obtain 6%Cu / TiO2-3%N.

[0044] (3) Weigh 0.1929 g of palladium nitrate and dissolve it in 50 mL of deionized water. Add 0.1293 g of polyvinylpyrrolidone, heat to 70 °C and stir for 2 h. Add the 6% Cu / TiO2-3%N prepared in step (2), and continue to stir for 4 h. Add 1 mol / L potassium hydroxide solution to adjust the pH of the mixture to 10, and continue to stir for 2 h. Slowly add 1.3 mL of 85 wt% hydrazine hydrate solution to the obtained suspension, maintain the temperature for 2 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven at 80 °C for 12 h to obtain 4% Pd-6% Cu / TiO2-3%N.

[0045] Example 3

[0046] (1) Dissolve 0.1144 g of alanine in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 30 min to obtain solution A; dissolve 5 mL of tetraisopropyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 10 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 90 °C for 9 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace and calcine at 300 °C for 4 h, and cool to room temperature to obtain TiO2-5%N.

[0047] (2) Weigh 0.3910g of copper sulfate and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 60℃ for 7h, put the product into a vacuum drying oven and dry at 80℃ for 12h, then put it into a muffle furnace and calcine at 300℃ for 4h to obtain 7%Cu / TiO2-5%N.

[0048] (3) Weigh 0.1654 g of dichlorotetraamminepalladium and dissolve it in 50 mL of deionized water. Add 0.1278 g of ethylenediamine, heat to 60 °C and stir for 3 h. Add the 7% Cu / TiO2-5%N prepared in step (2), and continue to heat and stir for 5 h. Add 1 mol / L ammonia solution to adjust the pH of the mixture to 9, and continue to heat and stir for 1 h. Slowly add 1.4 mL of 85 wt% hydrazine hydrate solution to the obtained suspension, maintain the temperature for 0.5 h, turn off the heating, and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 100 °C for 10 h to obtain 3% Pd-7% Cu / TiO2-5%N.

[0049] Example 4

[0050] (1) Dissolve 0.0192 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 10 min to obtain solution A; dissolve 5 mL of tetraethyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 10 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 2 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 60 °C for 12 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-2%N.

[0051] (2) Weigh 0.3281g of copper nitrate and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-2%N obtained in step (1), stir at 50℃ for 8h, put the product into a vacuum drying oven and dry at 90℃ for 11h, then calcine in a muffle furnace at 400℃ for 4h to obtain 5%Cu / TiO2-2%N.

[0052] (3) Weigh 0.3082 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1318 g of glucose, heat to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-2%N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L potassium hydroxide solution to adjust the pH of the mixture to 10, and continue to heat and stir for 2 h. Slowly add 2.1 mL of 40 wt% formaldehyde solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 5% Pd-5% Cu / TiO2-2%N.

[0053] Example 5

[0054] (1) Dissolve 0.0764 g of alanine in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 30 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 3 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 90 °C for 8 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 300 °C for 2 h, and cool it to room temperature to obtain TiO2-4%N.

[0055] (2) Weigh 0.2762g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-2%N obtained in step (1), stir at 70℃ for 6h, put the product into a vacuum drying oven and dry at 110℃ for 9h, and calcine in a muffle furnace at 500℃ for 2h to obtain 6%Cu / TiO2-4%N.

[0056] (3) Weigh 0.1079 g of dichlorotetraamminepalladium and dissolve it in 50 mL of deionized water. Add 0.1192 g of polyvinylpyrrolidone, heat to 60 °C and stir for 2 h. Add the 6% Cu / TiO2-4%N prepared in step (2) and continue stirring for 4 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 12 and continue stirring for 2 h. Slowly add 3.8 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1.5 h for reduction, then turn off the heating and stir at room temperature for 0.5 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 90 °C for 10 h to obtain 2% Pd-6% Cu / TiO2-4%N.

[0057] Example 6

[0058] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0059] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2-5%N.

[0060] (3) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1206 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-5%N prepared in step (2), and continue stirring for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10, and continue stirring for 1 h. Slowly add 3.6 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1 h, turn off the heating, and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd-5% Cu / TiO2-5%N. Figure 1 As shown, in the XRD diffraction pattern of the 3%Pd-5%Cu / TiO2-5%N catalyst, apart from the diffraction peaks of the anatase phase titanium dioxide, the diffraction peaks of palladium are not obvious, and there are no diffraction peaks of copper. This indicates that the metal content of palladium and copper is low and the nanoparticles are dispersed and small in size, which may also indicate the formation of a Pd-Cu alloy phase; Figure 2 As shown, metal nanoparticles can be uniformly dispersed on the carrier surface, with their size mainly distributed in the range of 2-4 nm; Figure 3 As shown, Pd and Cu nanoparticles are highly dispersed on the support surface. Furthermore, Pd and Cu appear in the same region and are in close contact with each other, indicating a certain interaction between the Pd and Cu components, suggesting the possible formation of an alloy structure of nanoparticles.

[0061] Example 7

[0062] (1) Dissolve 0.0162 g of melamine in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 10 min to obtain solution A; dissolve 5 mL of tetraisopropyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 20 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 2 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 60 °C for 12 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 300 °C for 4 h, and cool it to room temperature to obtain TiO2-3%N.

[0063] (2) Weigh 0.5432g of copper nitrate and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-3%N obtained in step (1), stir at 70℃ for 6h, put the product into a vacuum drying oven and dry at 100℃ for 11h, and calcine in a muffle furnace at 400℃ for 2h to obtain 8%Cu / TiO2-3%N.

[0064] (3) Weigh 0.2852 g of dichlorotetraamminepalladium and dissolve it in 50 mL of deionized water. Add 0.1414 g of polyvinylpyrrolidone, heat to 60 °C and stir for 3 h. Add the 8% Cu / TiO2-3%N prepared in step (2) and continue stirring for 4 h. Add 1 mol / L ammonia solution to adjust the pH of the mixture to 9 and continue stirring for 2 h. Slowly add 1.7 mL of 85 wt% hydrazine hydrate solution to the obtained suspension, maintain the temperature for 2 h, turn off the heating, and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 100 °C for 10 h to obtain 5% Pd-8% Cu / TiO2-3%N.

[0065] Example 8

[0066] (1) Dissolve 0.0154 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 10 min to obtain solution A; dissolve 5 mL of tetraisopropyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 10 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 2 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 450 °C for 2 h, and cool it to room temperature to obtain TiO2-2%N.

[0067] (2) Weigh 0.3351g of copper sulfate and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-2%N obtained in step (1), stir at 60℃ for 5h, put the product into a vacuum drying oven and dry at 80℃ for 10h, then put it into a muffle furnace and calcine at 300℃ for 2h to obtain 6%Cu / TiO2-2%N.

[0068] (3) Weigh 0.1932 g of palladium nitrate and dissolve it in 50 mL of deionized water. Add 0.1264 g of ethylenediamine, heat to 70 °C and stir for 2 h. Add the 6% Cu / TiO2-2%N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L potassium hydroxide solution to adjust the pH of the mixture to 11, and continue to heat and stir for 1.5 h. Slowly add 2.8 mL of 40 wt% sodium borohydride solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 80 °C for 12 h to obtain 4% Pd-6% Cu / TiO2-2%N.

[0069] Example 9

[0070] (1) Dissolve 0.0180 g of melamine in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 3 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 500 °C for 2 h, and cool it to room temperature to obtain TiO2-4%N.

[0071] (2) Weigh 0.0901g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-4%N obtained in step (1), stir at 70℃ for 5h, put the product into a vacuum drying oven and dry at 90℃ for 12h, then put it into a muffle furnace and calcine at 400℃ for 2h to obtain 2%Cu / TiO2-4%N.

[0072] (3) Weigh 0.2360g sodium tetrachloropalladium and dissolve it in 50mL of deionized water. Add 0.1163g polyvinylpyrrolidone, heat to 60℃ and stir for 3h. Add the 2% Cu / TiO2-4%N prepared in step (2), and continue to heat and stir for 4h. Add 1mol / L sodium hydroxide solution to adjust the pH of the mixture to 10, and continue to heat and stir for 2h. Slowly add 1.2mL of 40wt% formaldehyde solution to the obtained suspension, maintain the temperature for 2h to reduce, then turn off the heating and stir at room temperature for 1h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven at 110℃ for 10h to obtain 4%Pd-2%Cu / TiO2-4%N.

[0073] Example 10

[0074] (1) Dissolve 0.0285 g of alanine in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetraethyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 10 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 2 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 90 °C for 8 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 3 h, and cool it to room temperature to obtain TiO2-1%N.

[0075] (2) Weigh 0.1587g of copper sulfate and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-1%N obtained in step (1), stir at 70℃ for 6h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 300℃ for 4h to obtain 3%Cu / TiO2-1%N.

[0076] (3) Weigh 0.1045 g of dichlorotetraamminepalladium and dissolve it in 50 mL of deionized water. Add 0.1131 g of glucose, heat to 70 °C and stir for 2 h. Add the 3% Cu / TiO2-1%N prepared in step (2) and continue stirring for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 11 and continue stirring for 1 h. Slowly add 1.4 mL of 40% sodium borohydride solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven at 80 °C for 12 h to obtain 2% Pd-3% Cu / TiO2-1%N.

[0077] Example 11

[0078] (1) Dissolve 0.0129 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 10 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 10 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 2 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 500 °C for 2 h, and cool it to room temperature to obtain TiO2-2%N.

[0079] (2) Weigh 0.1244g of copper nitrate and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-2%N obtained in step (1), stir at 70℃ for 5h, put the product into a vacuum drying oven and dry at 100℃ for 9h, and calcine in a muffle furnace at 300℃ for 2h to obtain 2%Cu / TiO2-2%N.

[0080] (3) Weigh 0.1752 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1150 g of polyvinylpyrrolidone, heat to 60 °C and stir for 1 h. Add the 2% Cu / TiO2-2%N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L ammonia solution to adjust the pH of the mixture to 9, and continue to heat and stir for 2 h. Slowly add 0.6 mL of 85 wt% hydrazine hydrate solution to the obtained suspension, maintain the temperature for 2 h, turn off the heating, and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 100 °C for 10 h to obtain 3% Pd-2% Cu / TiO2-2%N.

[0081] Example 12

[0082] (1) Dissolve 0.0202 g of melamine in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetraethyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 30 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 3 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 90 °C for 12 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 300 °C for 4 h, and cool it to room temperature to obtain TiO2-3%N.

[0083] (2) Weigh 0.1783g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min. Add 2g of TiO2-3%N obtained in step (1). Stir at 60℃ for 6h. Place the product in a vacuum drying oven and dry at 80℃ for 12h. Place it in a muffle furnace and calcine at 400℃ for 2h to obtain 4%Cu / TiO2-3%N.

[0084] (3) Weigh 0.0522 g of dichlorotetraamminepalladium and dissolve it in 50 mL of deionized water. Add 0.1115 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the 4% Cu / TiO2-3%N prepared in step (2) and continue stirring for 4 h. Add 1 mol / L potassium hydroxide solution to adjust the pH of the mixture to 11 and continue stirring for 2 h. Slowly add 1.5 mL of 40 wt% sodium borohydride solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven at 80 °C for 12 h to obtain 1% Pd-4% Cu / TiO2-3%N.

[0085] Example 13

[0086] The application of different nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalysts prepared in Examples 1 to 12 in the selective catalytic hydrogenation reaction to prepare dibenzyl alcohol was investigated.

[0087] In a 600 ml stainless steel reactor, 30 g benzophenone, 200 mL methanol, 0.12 g sodium hydroxide, and 0.6 g of the nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst prepared above were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80 °C and the hydrogen pressure to 1.0 MPa. Stirring was started at a rate of 700 r / min, and the reaction was carried out for 2 h. The reaction was stopped, and after the temperature cooled to room temperature, the reaction solution was removed, the catalyst was removed by filtration, and the filtrate was analyzed by gas chromatography. The experimental results are shown in Table 1.

[0088] Table 1 Catalytic hydrogenation performance of palladium-copper bimetallic catalysts supported on different nitrogen-doped titanium dioxide.

[0089] Example 1 100 98.3 Example 2 100 98.9 Example 3 99.4 99.5 Example 4 100 98.9 Example 5 98.5 98.2 Example 6 100 99.7 Example 7 100 99.2 Example 8 100 98.6 Example 9 100 97.5 Example 10 98.3 95.7 Example 11 99.6 96.4 Example 12 97.8 99.3

[0090] Examples 14 to 21

[0091] In a 600ml stainless steel reactor, 30g benzophenone, 200mL methanol, 0.12g sodium hydroxide, and 0.6g of the 3%Pd-5%Cu / TiO2-5%N catalyst prepared in Example 6 were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. After the temperature and hydrogen pressure reached the required reaction range, stirring was started at a rate of 700 r / min, and the reaction was carried out for 2 hours. The reaction was stopped, and after the temperature cooled to room temperature, the reaction solution was removed, filtered to remove the catalyst, and the filtrate was analyzed by gas chromatography. The experimental results are shown in Table 2.

[0092] Table 2 Catalytic performance of nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalysts under different hydrogenation reaction conditions.

[0093] 14 70℃, 2MPa 99.6 98.7 15 70℃, 0.5MPa 99.1 98.9 16 60℃, 2MPa 98.8 97.9 17 60℃, 3MPa 99.3 98.2 18 80℃, 2MPa 100 99.2 19 80℃, 0.5MPa 99.8 99.4 20 90℃, 2MPa 100 98.4 21 90℃, 1MPa 100 98.8

[0094] Example 22

[0095] Example 22 investigated the reusability of the nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst prepared in Example 6 for the selective catalytic hydrogenation of benzophenone to dibenzyl alcohol. In a 600 ml stainless steel reactor, 30 g of benzophenone, 200 mL of methanol, 0.12 g of sodium hydroxide, and 0.6 g of the 3% Pd-5% Cu / TiO2-5% N catalyst prepared in Example 6 were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen was introduced. The temperature was raised to 80 °C and the hydrogen pressure to 1.0 MPa. Stirring was started at a rate of 700 r / min, and the reaction was carried out for 2 h. The reaction was stopped, and after the temperature cooled to room temperature, the reaction solution was removed, the catalyst was removed by filtration, and the filtrate was analyzed by gas chromatography. The catalyst was reused in the experiment, with 0.03 g of fresh catalyst from Example 6 added before each addition. The experimental conditions were the same, and the results are shown in Table 3.

[0096] Table 3. Application performance of nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalysts

[0097] 1 100 99.8 2 100 99.5 3 99.8 100 4 99.9 99.7 5 100 99.8 6 99.8 99.7 7 98.7 99.4 8 99.3 99.5 9 100 99.7 10 99.8 99.6

[0098] Comparative Example 1 (compared to Example 6)

[0099] Comparative Example 1 investigated the reaction performance of a titanium dioxide-supported palladium-copper bimetallic catalyst.

[0100] (1) Dissolve 5 mL of deionized water and 2 mL of concentrated nitric acid in 25 mL of anhydrous ethanol and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2.

[0101] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2.

[0102] (3) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1206 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-5% N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10, and continue to heat and stir for 1 h. Slowly add 3.6 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd-5% Cu / TiO2.

[0103] (4) In a 600ml stainless steel reactor, 30g benzophenone, 200mL methanol, 0.12g sodium hydroxide, and 0.6g of the prepared 3%Pd-5%Cu / TiO2 catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80℃ and the hydrogen pressure was 1.0MPa. Stirring was started at a speed of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, filtered to remove the catalyst, and the filtrate was analyzed by gas chromatography. The experimental results showed a conversion rate of 83.6% and a selectivity of 88.5%.

[0104] Comparative Example 2 (compared to Example 6)

[0105] Comparative Example 2 investigated the reaction performance of a nitrogen-doped titanium dioxide-supported palladium catalyst.

[0106] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0107] (2) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1090 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the TiO2-5%N prepared in step (2) and continue stirring for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10 and continue stirring for 1 h. Slowly add 1.0 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd / TiO2-5%N.

[0108] (3) In a 600ml stainless steel reactor, 30g benzophenone, 200mL methanol, 0.12g sodium hydroxide, and 0.6g of the prepared 3%Pd-5%Cu / TiO2 catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80℃ and the hydrogen pressure was 1.0MPa. Stirring was started at a speed of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, the catalyst was removed by filtration, and the filtrate was analyzed by gas chromatography. The experimental results showed that the conversion rate was 100% and the selectivity was 34.7%.

[0109] Comparative Example 3 (compared to Example 6)

[0110] Comparative Example 3 investigated the reaction performance of a nitrogen-doped titanium dioxide-supported copper catalyst.

[0111] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0112] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2-5%N.

[0113] (3) In a 600ml stainless steel reactor, 30g benzophenone, 200mL methanol, 0.12g sodium hydroxide, and 0.6g of the prepared 5% Cu / TiO2-5%N catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80℃ and the hydrogen pressure was 1.0MPa. Stirring was started at a rate of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was removed by filtration, and the filtrate was analyzed by gas chromatography. The experimental results showed a conversion rate of 73.6% and a selectivity of 81.2%.

[0114] Comparative Example 4 (compared to Example 6)

[0115] Comparative Example 4 investigated the effect of dispersant on the reaction performance of nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst.

[0116] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0117] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2-5%N.

[0118] (3) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Heat the solution to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-5%N prepared in step (2) and continue stirring for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10 and continue stirring for 1 h. Slowly add 3.6 mL of 30 wt% formic acid solution to the resulting suspension. After maintaining the temperature for 1 h, turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd-5% Cu / TiO2-5%N.

[0119] (4) In a 600ml stainless steel reactor, 30g benzophenone, 200mL methanol, 0.12g sodium hydroxide, and 0.6g of the prepared 3%Pd-5%Cu / TiO2-5%N catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80℃ and the hydrogen pressure was 1.0MPa. Stirring was started at a speed of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, filtered to remove the catalyst, and the filtrate was analyzed by gas chromatography. The experimental results showed a conversion rate of 84.6% and a selectivity of 88.2%.

[0120] Comparative Example 5 (compared to Example 6)

[0121] Comparative Example 5 investigated the effect of reaction temperature on the performance of selective catalytic hydrogenation.

[0122] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0123] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2-5%N.

[0124] (3) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1206 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-5%N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10, and continue to heat and stir for 1 h. Slowly add 3.6 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd-5% Cu / TiO2-5%N.

[0125] (4) In a 600ml stainless steel reactor, 30g benzophenone, 200mL methanol, 0.12g sodium hydroxide, and 0.6g of the prepared 3%Pd-5%Cu / TiO2-5%N catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 100℃ and the hydrogen pressure was 1.0MPa. Stirring was started at a speed of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, filtered to remove the catalyst, and the filtrate was analyzed by gas chromatography. The experimental results showed a conversion rate of 98.5% and a selectivity of 82.3%.

[0126] Comparative Example 6

[0127] Comparative Example 6 investigated the effect of hydrogen pressure on the performance of selective catalytic hydrogenation.

[0128] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0129] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2-5%N.

[0130] (3) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1206 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-5%N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10, and continue to heat and stir for 1 h. Slowly add 3.6 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd-5% Cu / TiO2-5%N.

[0131] (4) In a 600ml stainless steel reactor, 30g benzophenone, 200mL methanol, 0.12g sodium hydroxide, and 0.6g of the prepared 3%Pd-5%Cu / TiO2-5%N catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80℃ and the hydrogen pressure was 3.5MPa. Stirring was started at a speed of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was removed by filtration, and the filtrate was analyzed by gas chromatography. The experimental results showed a conversion rate of 96.5% and a selectivity of 76.3%.

[0132] Comparative Example 7

[0133] Comparative Example 7 investigated the effect of catalyst dosage on the performance of selective catalytic hydrogenation.

[0134] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0135] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2-5%N.

[0136] (3) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1206 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-5%N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10, and continue to heat and stir for 1 h. Slowly add 3.6 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd-5% Cu / TiO2-5%N.

[0137] (4) In a 600ml stainless steel reactor, 30g benzophenone, 200mL methanol, 0.06g sodium hydroxide, and 0.3g of the prepared 3%Pd-5%Cu / TiO2-5%N catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80℃ and the hydrogen pressure was 1MPa. Stirring was started at a speed of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, filtered to remove the catalyst, and the filtrate was analyzed by gas chromatography. The experimental results showed a conversion rate of 87.4% and a selectivity of 83.9%.

[0138] Comparative Example 8

[0139] Comparative Example 8 investigated the effect of feedstock concentration on the performance of selective catalytic hydrogenation.

[0140] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0141] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2-5%N.

[0142] (3) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1206 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-5%N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10, and continue to heat and stir for 1 h. Slowly add 3.6 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd-5% Cu / TiO2-5%N.

[0143] (4) In a 600ml stainless steel reactor, 10g benzophenone, 200mL methanol, 0.04g sodium hydroxide, and 0.2g of the prepared 3%Pd-5%Cu / TiO2-5%N catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80℃ and the hydrogen pressure was 1MPa. Stirring was started at a speed of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, filtered to remove the catalyst, and the filtrate was analyzed by gas chromatography. The experimental results showed a conversion rate of 88.7% and a selectivity of 86.8%.

[0144] Comparative Example 9

[0145] Comparative Example 9 investigated the effect of solvent on the performance of selective catalytic hydrogenation.

[0146] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0147] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2-5%N.

[0148] (3) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1206 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-5%N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10, and continue to heat and stir for 1 h. Slowly add 3.6 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd-5% Cu / TiO2-5%N.

[0149] (4) In a 600ml stainless steel reactor, 30g benzophenone, 200mL ethanol, 0.12g sodium hydroxide, and 0.6g of the prepared 3%Pd-5%Cu / TiO2-5%N catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80℃ and the hydrogen pressure was 1MPa. Stirring was started at a speed of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was taken out, filtered to remove the catalyst, and the filtrate was analyzed by gas chromatography. The experimental results showed a conversion rate of 81.6% and a selectivity of 90.3%.

[0150] Comparative Example 10

[0151] Comparative Example 10 investigated the effect of basic additives on the performance of selective catalytic hydrogenation.

[0152] (1) Dissolve 0.0322 g of urea in a mixed solution consisting of 5 mL of deionized water, 25 mL of anhydrous ethanol, and 2 mL of concentrated nitric acid, and stir at room temperature for 15 min to obtain solution A; dissolve 5 mL of tetrabutyl titanate in 25 mL of anhydrous ethanol, and stir at room temperature for 15 min to obtain solution B. While stirring, slowly add solution A to solution B and stir for 4 h to obtain a transparent sol. Allow it to stand and air dry at room temperature until a transparent gel is formed. Place the obtained gel in a vacuum drying oven at 80 °C for 10 h. Grind it with an agate mortar to obtain a dry gel powder, place it in a muffle furnace at 400 °C for 2 h, and cool it to room temperature to obtain TiO2-5%N.

[0153] (2) Weigh 0.2301g of copper chloride and dissolve it in 50mL of deionized water. Stir at room temperature for 30min, add 2g of TiO2-5%N obtained in step (1), stir at 70℃ for 8h, put the product into a vacuum drying oven and dry at 110℃ for 8h, and calcine in a muffle furnace at 450℃ for 2h to obtain 5%Cu / TiO2-5%N.

[0154] (3) Weigh 0.1809 g of sodium tetrachloropalladium and dissolve it in 50 mL of deionized water. Add 0.1206 g of polyethylene glycol, heat to 70 °C and stir for 2 h. Add the 5% Cu / TiO2-5%N prepared in step (2), and continue to heat and stir for 3 h. Add 1 mol / L sodium hydroxide solution to adjust the pH of the mixture to 10, and continue to heat and stir for 1 h. Slowly add 3.6 mL of 30 wt% formic acid solution to the obtained suspension, maintain the temperature for 1 h to reduce, then turn off the heating and stir at room temperature for 1 h. Filter the suspension and wash it with deionized water until the pH of the filtrate is neutral. Place the obtained sample in a vacuum drying oven and dry at 110 °C for 8 h to obtain 3% Pd-5% Cu / TiO2-5%N.

[0155] (4) In a 600ml stainless steel reactor, 30g benzophenone, 200mL methanol, and 0.6g of the prepared 3%Pd-5%Cu / TiO2-5%N catalyst were added sequentially. The air in the reactor was replaced with hydrogen gas, and hydrogen gas was introduced. The temperature was raised to 80℃ and the hydrogen pressure was 1MPa. Stirring was started at a speed of 700r / min, and the reaction was carried out for 2h. The reaction was stopped, and after the temperature dropped to room temperature, the reaction solution was removed, the catalyst was removed by filtration, and the filtrate was analyzed by gas chromatography. The experimental results showed a conversion rate of 96.3% and a selectivity of 88.5%.

Claims

1. A method for preparing a nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst, characterized in that: The specific steps of the preparation method are as follows: (1) Preparation of nitrogen-doped titanium dioxide support: Nitrogen-containing organic matter was dissolved in a mixed solution composed of deionized water, anhydrous ethanol and concentrated nitric acid, and stirred evenly at room temperature to obtain solution A; then an appropriate amount of titanium-containing organic matter was dissolved in anhydrous ethanol, and stirred evenly at room temperature to obtain solution B; then, while stirring, solution A was slowly added to solution B, and stirring was continued for 2-4 hours until a transparent sol was formed, which was then allowed to stand and air dry at room temperature until a transparent gel was formed; this gel was placed in a vacuum drying oven and dried at 60-90℃ for 8-12 hours; then, it was ground with an agate mortar to obtain dry gel powder; finally, the dry gel powder was placed in a muffle furnace and calcined at 300-500℃ for 2-4 hours, and cooled to room temperature to obtain nitrogen-doped titanium dioxide support, which was denoted as TiO2-xN, where x represents the molar percentage of nitrogen element in titanium element, x = 1%-5%; (2) Weigh a certain amount of copper-containing compound and dissolve it in an appropriate amount of deionized water. Stir at room temperature to obtain a uniform solution. Add the nitrogen-doped titanium dioxide obtained in step (1) and stir at 50-70℃ for 5-8h. Place the obtained product in a vacuum drying oven and dry at 80-110℃ for 8-12h. Place the obtained solid in a muffle furnace and calcine at 300-500℃ for 2-4h to obtain Cu / TiO2-xN. (3) Take a certain amount of palladium-containing compound and add it to an appropriate amount of deionized water. Add an appropriate amount of dispersant, heat to 50-70℃ and keep stirring for 1-3 hours. Add the Cu / TiO2-xN obtained in step (2) and continue stirring for 3-5 hours. Slowly add an aqueous solution of alkaline substance to the above suspension, adjust the pH value of the solution to 9.0-12.0, and continue stirring for 0.5-2 hours. Slowly add liquid phase reducing agent to the obtained suspension, keep the temperature and reduce for 0.5-2 hours. After the reduction is completed, turn off the heating and stir at room temperature for 0.5-1 hours. Filter the above suspension and wash it with deionized water until the pH of the filtrate is neutral. The obtained sample is dried under vacuum to obtain nitrogen-doped titanium dioxide supported palladium-copper dual catalyst, in which the loading of Cu is 2wt%-8wt% and the loading of Pd is 1wt%-5wt%.

2. The preparation method according to claim 1, characterized in that: In step (1), the nitrogen-containing organic compound is at least one of urea, alanine, and melamine, and the titanium-containing organic compound is at least one of tetraethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate.

3. The preparation method according to claim 1, characterized in that: In step (2), the copper-containing compound is at least one of copper chloride, copper nitrate, and copper sulfate.

4. The preparation method according to claim 1, characterized in that: In step (3), the palladium-containing compound solution is at least one of sodium tetrachloropalladium, palladium nitrate, and dichlorotetraamminepalladium; the dispersant is at least one of polyethylene glycol, polyvinylpyrrolidone, ethylenediamine, and glucose; and the alkaline substance is sodium hydroxide, potassium hydroxide, or ammonia.

5. The preparation method according to claim 1, characterized in that: In step (3), the liquid phase reducing agent is hydrazine hydrate, formic acid, formaldehyde, or an aqueous solution of sodium borohydride.

6. The preparation method according to claim 1, characterized in that: x = 5%, with Pd and Cu loadings of 3% and 5%, respectively.

7. A nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst prepared by the preparation method according to any one of claims 1-6.

8. The application of the nitrogen-doped titanium dioxide supported palladium-copper bimetallic catalyst as described in claim 7 in the selective catalytic hydrogenation of benzophenone to dibenzyl alcohol.

9. The application as described in claim 8, characterized in that: The selective catalytic hydrogenation of benzophenone to diphenylmethanol is specifically implemented according to the following steps: Benzophenone, an organic solvent, sodium hydroxide, and a nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst are added sequentially to a reaction vessel. The organic solvent is methanol, and the mass ratio of the nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst to benzophenone is ≥0.

02. The air in the reaction vessel is replaced with hydrogen, and hydrogen is introduced. The reaction is carried out at 0.5-3 MPa and 60-90℃ for 1-4 hours. The resulting reaction solution is filtered to remove the catalyst, and the filtrate is distilled or purified to obtain diphenylmethanol.

10. The application as described in claim 9, characterized in that: The mass ratio of sodium hydroxide to nitrogen-doped titanium dioxide-supported palladium-copper bimetallic catalyst is 0.2.

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