Preparation method of salt-resistant bimetallic supported catalyst and application of salt-resistant bimetallic supported catalyst in polyol hydrogenation or oxidation reaction

Abstract

The invention provides a preparation method of a salt-resistant bimetallic supported catalyst and application of the salt-resistant bimetallic supported catalyst in polyol hydrogenation or oxidation reaction, and belongs to the technical field of catalysts. The preparation method comprises the steps of metal oxide carrier pretreatment, salt washing treatment, first roasting treatment, dipping treatment, second roasting treatment and desalination treatment. By accurately controlling the conditions of each step and adopting an electrochemical desalting process, the residual salt on the surface of the catalyst is successfully removed, and the stability and activity of the catalyst in a high-salt environment are improved. The bimetallic supported catalyst prepared by the invention can be effectively applied to hydrogenation and oxidation reactions of polyol, and has remarkable salt resistance, excellent catalytic efficiency and long-term stability. The catalyst provided by the invention has high reaction conversion rate and selectivity, shows stronger anti-recession ability in a high salt concentration environment, and solves the technical problem that the existing catalyst loses efficacy in a salt environment.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a method for preparing a salt-resistant bimetallic supported catalyst and application of the catalyst in hydrogenation or oxidation reactions of polyols. Background Art

[0002] Polyols (such as glycerol, ethylene glycol, propylene glycol, etc.) are important chemical raw materials and are widely used in energy, environmental protection and chemical industries. In the hydrogenation and oxidation reactions of polyols, the performance of the catalyst directly affects the reaction efficiency. However, the activity of traditional catalysts declines in high-salt environments, and the catalytic efficiency decreases, which limits their application in certain industrial processes.

[0003] Existing catalysts use metal oxides (such as Al2O3, TiO2, etc.) as carriers, and active metals are loaded by methods such as metal impregnation and calcination. However, traditional supported catalysts are easily affected by salt ions in high-salt environments, causing the active sites on the catalyst surface to be covered by salt, thereby causing the catalyst to lose activity and significantly reducing the catalytic efficiency. In addition, in the preparation process of existing catalysts, insufficient attention has been paid to the removal of salt on the catalyst surface. Simple physical washing methods are usually used to remove residual salt, but these methods are often inefficient and cannot completely remove salt, resulting in a significant decline in the activity and stability of the catalyst. Therefore, it is urgent to develop a catalyst that can maintain high catalytic activity in a high-salt environment. Summary of the invention

[0004] In view of this, the present invention provides a method for preparing a salt-resistant bimetallic supported catalyst. The method significantly improves the stability and activity of the catalyst in a high salt concentration environment through the synergistic effect of metal oxide carriers and precious metals and transition metals, and adopts innovative pretreatment and desalination processes, thereby providing a new solution for the hydrogenation and oxidation reactions of polyols.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: A method for preparing a salt-resistant bimetallic supported catalyst comprises the following steps: (1) Pretreatment of metal oxide carrier: pretreatment of the metal oxide carrier to remove impurities on the surface of the metal oxide; the metal oxide carrier is at least one of Al2O3, TiO2, CeO2, and ZrO2; this step can improve the surface properties of the carrier and enhance the dispersion and stability of the catalyst; (2) Salt washing treatment: The pretreated metal oxide carrier is salt washed with a salt solution, and then washed with water to remove excess salt. The salt washing treatment uses a salt solution of a specific concentration to remove possible dissolved salts and impurities, further improving the salt resistance of the catalyst. (3) First calcination treatment: calcination treatment is carried out by heating under the protection of inert gas; (4) Impregnation treatment: the carrier after the first calcination is impregnated in a mixed solution containing a noble metal salt and a transition metal salt, and dried after the impregnation is completed to obtain a metal-loaded carrier; the noble metal salt is at least one of Pt, Pd, and Rh metal salts, and the transition metal salt is at least one of Cu and W metal salts; the elemental mass ratio of the noble metal to the transition metal is 1:1 to 1:10; the sum of the mass of the noble metal and the transition metal in the mixed solution is 2 to 7% of the mass of the carrier; the noble metal is responsible for the main activity of the catalytic reaction, while the transition metal provides auxiliary effects to enhance the durability and salt resistance of the catalyst; (5) Second calcination treatment: heating the metal-loaded carrier for a second calcination treatment; (6) Desalination treatment: The electrochemical desalination process is used to remove the salt remaining on the surface, and the catalyst is taken out, washed and dried to obtain the salt-resistant bimetallic supported catalyst.

[0006] Preferably, the pretreatment in step (1) is acid washing or alkali washing; The acid washing adopts a dilute nitric acid solution with a concentration of 0.1-1 mol / L; the ratio of the metal oxide carrier to the dilute nitric acid solution is 1 g: 30-80 mL; and the treatment time of the acid washing is 0.5-5 h.

[0007] The alkali washing adopts a sodium hydroxide solution with a concentration of 0.5-2 mol / L; the ratio of the metal oxide carrier to the sodium hydroxide solution is 1 g: 20-40 mL; and the treatment time of the alkali washing is 0.5-5 h.

[0008] Preferably, the salt solution in step (2) is a sodium chloride solution with a concentration of 0.5-5wt%, and the salt washing treatment time is 0.5-10 h.

[0009] Preferably, the inert gas in step (3) is any one of nitrogen, helium and argon; the calcination temperature is 400-800°C, the time is 2-6 h; and the heating rate is 2-10°C / min.

[0010] Preferably, the precious metal salt in step (4) is at least one of chloroplatinic acid hexahydrate, potassium chloroplatinate, platinum nitrate, palladium nitrate, and rhodium chloride; and the transition metal salt is at least one of copper nitrate, ammonium metatungstate, and ammonium paratungstate.

[0011] Preferably, the drying temperature in step (4) is 80-120°C and the drying time is 12-24 hours.

[0012] Preferably, the temperature of the second calcination in step (5) is 300-600°C, and the time is 2-6 h; the heating rate is 2-10°C / min; and the second calcination temperature is lower than the first calcination temperature.

[0013] Preferably, in the electrochemical desalination device of step (6), the anode material is a platinum electrode, the cathode material is a copper electrode, and the electrolyte solution is a 0.5 mol / L sodium sulfate solution; the voltage of the electrochemical desalination device is 3-10 V, the electrolysis time is 2-8 h, the electrolysis temperature is 20-60 °C, and the stirring rate is 100-500 rpm; The drying temperature in step (6) is 80-100°C; the drying time is 12-24 hours.

[0014] Another object of the present invention is to provide a use of the catalyst prepared by the above method, wherein the catalyst is used for hydrogenation or oxidation reaction of polyols in an aqueous phase, wherein the polyols are at least one of glycerol, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol or sugars containing multiple hydroxyls, wherein the sugars containing multiple hydroxyls include any one of glucose, mannose and xylose; The reaction temperature is 50-200°C, the reaction time is 0.5-48 h, and the reaction pressure is 0.1-4.0 MPa.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) Excellent salt resistance: Through the innovative electrochemical desalination process, the present invention can effectively remove residual salt on the catalyst surface, significantly improve the stability and catalytic activity of the catalyst in a high salt concentration environment, and solve the problem of activity degradation of traditional catalysts in a salt environment.

[0016] (2) Improving catalytic efficiency and long-term stability: The prepared catalyst exhibits excellent catalytic efficiency in the hydrogenation and oxidation reactions of polyols, and exhibits high conversion rate and high selectivity for a long time in a high-salt environment. It is significantly better than existing catalysts and has high long-term operating stability.

[0017] (3) Innovative electrochemical desalination process: Through electrochemical desalination, salt on the catalyst surface is accurately removed, avoiding the limitations of traditional physical washing methods, ensuring maximum exposure of the catalyst's active sites, and improving the catalyst's service life and economy. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the embodiments. Example 1

[0019] A method for preparing a salt-resistant Pt-Cu / Al2O3 catalyst, comprising the following steps: (1) Pretreatment of metal oxide carrier: Al2O3 was used as the carrier and pickled with a dilute nitric acid solution with a concentration of 0.5 mol / L. The ratio of the carrier to the solution was 1 g:50 mL, and the pickling time was 2 h. (2) Salt washing: The support after the above pretreatment was salt washed with 0.5 wt % sodium chloride solution for 8 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and calcined at a temperature of 600 °C, a calcination time of 4 h, and a heating rate of 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing platinum nitrate and copper nitrate, with a mass ratio of Pt to Cu of 1:5. The immersion time is 4 h, and the sum of the mass of the noble metal and transition metal in the mixed solution is 3% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and calcined again at a temperature of 450 °C for 3 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 5 V, the electrolysis time was 4 h, the electrolysis temperature was 40 °C, and the stirring rate was 300 rpm. The catalyst after electrolysis was dried at 100 °C for 12 h to obtain a salt-resistant Pt-Cu / Al2O3 catalyst. Example 2

[0020] A method for preparing a salt-resistant Pt-W / Al2O3 catalyst, the steps are as follows: (1) Pretreatment of metal oxide carrier: Al2O3 was used as the carrier and pickled with a dilute nitric acid solution with a concentration of 0.3 mol / L. The ratio of the carrier to the solution was 1 g: 60 mL, and the pickling time was 4 h. (2) Salt washing: The support after the above pretreatment was salt washed with 2 wt % sodium chloride solution for 10 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: placing the salt-washed carrier in a nitrogen atmosphere and heating it for calcination; the calcination temperature is 400 °C, the calcination time is 4 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing potassium chloroplatinate and ammonium metatungstate, with a mass ratio of Pt to W of 1:4. The immersion time is 2 h, and the sum of the mass of the noble metal and transition metal in the mixed solution is 6% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and calcined again at a temperature of 350 °C for 4 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 6 V, the electrolysis time was 6 h, the electrolysis temperature was 40 °C, and the stirring rate was 500 rpm. The catalyst after electrolysis was dried at 100 °C for 18 h to obtain a salt-resistant Pt-W / Al2O3 catalyst. Example 3

[0021] A method for preparing a salt-resistant Pd-W / ZrO2 catalyst comprises the following steps: (1) Pretreatment of metal oxide carrier: ZrO2 was used as the carrier and washed with a 1.5 mol / L sodium hydroxide solution. The ratio of the carrier to the solution was 1 g:40 mL and the washing time was 5 h. (2) Salt washing: The support after the above pretreatment was salt washed with 0.5 wt % sodium chloride solution for 10 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: placing the salt-washed carrier in an argon atmosphere and heating it for calcination; the calcination temperature is 500 °C, the calcination time is 5 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing palladium nitrate and ammonium metatungstate, with a mass ratio of Pd to W of 1:3. The impregnation time is 3 h, and the sum of the mass of the noble metal and transition metal in the mixed solution is 4% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in an argon atmosphere and calcined again at a temperature of 450 °C for 4 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 3 V, the electrolysis time was 2 h, the electrolysis temperature was 55 °C, and the stirring rate was 300 rpm. The catalyst after electrolysis was dried at 90 °C for 12 h to obtain a salt-resistant Pd-W / ZrO2 catalyst. Example 4

[0022] A method for preparing a salt-resistant Pt-W / CeO2 catalyst, the steps are as follows: (1) Pretreatment of metal oxide carrier: CeO2 was used as the carrier and acid-washed with a dilute nitric acid solution with a concentration of 0.2 mol / L. The ratio of the carrier to the solution was 1 g:80 mL, and the acid washing time was 5 h. (2) Salt washing: The support after the above pretreatment was salt washed with 1.5 wt% sodium chloride solution for 4 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and heated for calcination; the calcination temperature is 650 °C, the calcination time is 6 h, and the heating rate is 5 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing hexahydrate chloroplatinic acid and ammonium paratungstate, with a mass ratio of Pt to W of 1:8. The immersion time is 4 h, and the sum of the mass of the noble metal and transition metal in the mixed solution is 5% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and heated up for calcination again at a temperature of 550 °C for 6 h at a heating rate of 5 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 6 V, the electrolysis time was 6 h, the electrolysis temperature was 40 °C, and the stirring rate was 500 rpm. The catalyst after electrolysis was dried at 100 °C for 18 h to obtain a salt-resistant Pt-W / CeO2 catalyst. Example 5

[0023] A method for preparing a salt-resistant Pt-W / ZrO2 catalyst comprises the following steps: (1) Pretreatment of metal oxide carrier: ZrO2 was used as the carrier and pickled with a dilute nitric acid solution with a concentration of 0.2 mol / L. The ratio of the carrier to the solution was 1 g: 60 mL, and the pickling time was 5 h. (2) Salt washing: The pre-treated support was salt washed with a 4 wt % sodium chloride solution for 4 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: placing the salt-washed carrier in a helium atmosphere and heating it for calcination; the calcination temperature is 650 °C, the calcination time is 6 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing platinum nitrate and ammonium metatungstate, with a mass ratio of Pt to W of 1:8. The immersion time is 4 h, and the sum of the mass of the noble metal and transition metal in the mixed solution is 5% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a helium atmosphere and calcined again at a temperature of 550 °C for 6 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was adopted. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 6 V, the electrolysis time was 6 h, the electrolysis temperature was 40 °C, and the stirring rate was 500 rpm. The catalyst after electrolysis was dried at 100 °C for 20 h to obtain a salt-resistant Pt-W / ZrO2 catalyst. Example 6

[0024] A method for preparing a salt-resistant Pt-Cu / ZrO2 catalyst, comprising the following steps: (1) Pretreatment of metal oxide carrier: ZrO2 was used as the carrier and was pickled with a dilute nitric acid solution with a concentration of 0.8 mol / L. The ratio of the carrier to the solution was 1 g:80 mL, and the pickling time was 2 h. (2) Salt washing: The pre-treated support was salt washed with 5 wt % sodium chloride solution for 10 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and heated for calcination; the calcination temperature is 650 °C, the calcination time is 6 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing potassium chloroplatinate and copper nitrate, with a mass ratio of Pt to Cu of 1:10. The immersion time is 2 h, and the sum of the mass of the precious metal and transition metal in the mixed solution is 6% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and calcined again at a temperature of 600 °C for 6 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was adopted. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 4 V, the electrolysis time was 6 h, the electrolysis temperature was 55 °C, and the stirring rate was 500 rpm. The catalyst after electrolysis was dried at 100 °C for 12 h to obtain a salt-resistant Pt-Cu / ZrO2 catalyst. Example 7

[0025] A method for preparing a salt-resistant Pd-W / Al2O3 catalyst comprises the following steps: (1) Pretreatment of metal oxide carrier: Al2O3 was used as the carrier and pickled with a dilute nitric acid solution with a concentration of 0.5 mol / L. The ratio of the carrier to the solution was 1 g:30 mL, and the pickling time was 1.5 h. (2) Salt washing: The support after the above pretreatment was salt washed with 3 wt % sodium chloride solution for 6 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and heated for calcination; the calcination temperature is 600 °C, the calcination time is 5 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing palladium nitrate and ammonium metatungstate, with a mass ratio of Pd to W of 1:4. The impregnation time is 3 h, and the sum of the mass of the noble metal and transition metal in the mixed solution is 4% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and calcined again at a temperature of 500 °C for 5 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was adopted. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 6 V, the electrolysis time was 4 h, the electrolysis temperature was 60 °C, and the stirring rate was 200 rpm. The catalyst after electrolysis was dried at 100 °C for 18 h to obtain a salt-resistant Pd-W / Al2O3 catalyst. Example 8

[0026] A method for preparing a salt-resistant Pd-Cu / CeO2 catalyst, comprising the following steps: (1) Pretreatment of metal oxide carrier: CeO2 was used as the carrier and washed with a sodium hydroxide solution with a concentration of 0.5 mol / L. The ratio of the carrier to the solution was 1 g:30 mL, and the washing time was 2 h. (2) Salt washing: The support after the above pretreatment was salt washed with 0.5 wt % sodium chloride solution for 10 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and heated for calcination; the calcination temperature is 600°C, the calcination time is 4 h, and the heating rate is 2°C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing palladium nitrate and copper nitrate, with a mass ratio of Pd to Cu of 1:5. The immersion time is 4 h, and the sum of the mass of the precious metal and transition metal in the mixed solution is 3% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and calcined again at a temperature of 450 °C for 3 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 5 V, the electrolysis time was 4 h, the electrolysis temperature was 40 °C, and the stirring rate was 300 rpm. The catalyst after electrolysis was dried at 100 °C for 12 h to obtain a salt-resistant Pd-Cu / CeO2 catalyst. Example 9

[0027] A method for preparing a salt-resistant Pt-W / TiO2 catalyst, the steps are as follows: (1) Pretreatment of metal oxide carrier: TiO2 was used as the carrier and washed with a 1 mol / L sodium hydroxide solution. The ratio of the carrier to the solution was 1 g:20 mL and the washing time was 3 h. (2) Salt washing: The support after the above pretreatment was salt washed with 1 wt% sodium chloride solution for 8 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: placing the salt-washed carrier in an argon atmosphere and heating it for calcination; the calcination temperature is 550 °C, the calcination time is 6 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing potassium chloroplatinate and ammonium paratungstate, with a mass ratio of Pt to W of 1:6. The immersion time is 5 h, and the sum of the mass of the noble metal and transition metal in the mixed solution is 2% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and heated up for calcination again at a temperature of 500 °C for 6 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 5 V, the electrolysis time was 4 h, the electrolysis temperature was 40 °C, and the stirring rate was 500 rpm. The catalyst after electrolysis was dried at 100 °C for 12 h to obtain a salt-resistant Pt-W / TiO2 catalyst. Example 10

[0028] A method for preparing a salt-resistant Pd-Cu / Al2O3 catalyst comprises the following steps: (1) Pretreatment of metal oxide carrier: Al2O3 was used as the carrier and pickled with a dilute nitric acid solution with a concentration of 0.7 mol / L. The ratio of the carrier to the solution was 1 g:70 mL, and the pickling time was 4 h. (2) Salt washing: The pre-treated support was salt washed with 3 wt % sodium chloride solution for 5 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and heated for calcination; the calcination temperature is 700 °C, the calcination time is 5 h, and the heating rate is 5 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing palladium nitrate and copper nitrate, with a mass ratio of Pd to Cu of 1:6. The immersion time is 4 h, and the sum of the mass of the precious metal and transition metal in the mixed solution is 5% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and calcined again at a temperature of 600 °C for 5 h at a heating rate of 5 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 8 V, the electrolysis time was 4 h, the electrolysis temperature was 50 °C, and the stirring rate was 300 rpm. The catalyst after electrolysis was dried at 100 °C for 18 h to obtain a salt-resistant Pd-Cu / Al2O3 catalyst. Embodiment 11

[0029] A method for preparing a salt-resistant Pd-Cu / ZrO2 catalyst comprises the following steps: (1) Pretreatment of metal oxide carrier: ZrO2 was used as the carrier and was pickled with a dilute nitric acid solution with a concentration of 0.5 mol / L. The ratio of the carrier to the solution was 1 g:50 mL, and the pickling time was 1 h. (2) Salt washing: The support after the above pretreatment was salt washed with 2.5 wt% sodium chloride solution for 2 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and heated for calcination; the calcination temperature is 650 °C, the calcination time is 6 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing palladium nitrate and copper nitrate, with a mass ratio of Pd to Cu of 1:4. The immersion time is 3 h, and the sum of the mass of the precious metal and transition metal in the mixed solution is 3% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and calcined again at a temperature of 600 °C for 5 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was adopted. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 5 V, the electrolysis time was 5 h, the electrolysis temperature was 60 °C, and the stirring rate was 100 rpm. The catalyst after electrolysis was dried at 80 °C for 24 h to obtain a salt-resistant Pd-Cu / ZrO2 catalyst. Example 12

[0030] A method for preparing a salt-resistant Pd-Cu / TiO2 catalyst comprises the following steps: (1) Pretreatment of metal oxide carrier: TiO2 was used as the carrier and acid-washed with a dilute nitric acid solution with a concentration of 1 mol / L. The ratio of the carrier to the solution was 1 g:30 mL, and the acid washing time was 3 h. (2) Salt washing: The support after the above pretreatment was salt washed with 2 wt % sodium chloride solution for 4 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and heated for calcination; the calcination temperature is 600 °C, the calcination time is 5 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing palladium nitrate and copper nitrate, with a mass ratio of Pd to Cu of 1:8. The immersion time is 4 h, and the sum of the mass of the precious metal and transition metal in the mixed solution is 3% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and calcined again at a temperature of 550 °C for 5 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was adopted. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 8 V, the electrolysis time was 8 h, the electrolysis temperature was 45 °C, and the stirring rate was 500 rpm. The catalyst after electrolysis was dried at 100 °C for 24 h to obtain a salt-resistant Pd-Cu / TiO2 catalyst. Example 13

[0031] A method for preparing a salt-resistant Pt-Cu / TiO2 catalyst, the steps are as follows: (1) Pretreatment of metal oxide carrier: TiO2 was used as the carrier and acid-washed with a dilute nitric acid solution with a concentration of 0.4 mol / L. The ratio of the carrier to the solution was 1 g:40 mL, and the acid washing time was 4 h. (2) Salt washing: The pre-treated support was salt washed with a 5 wt % sodium chloride solution for 5 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: placing the salt-washed carrier in a helium atmosphere and heating it for calcination; the calcination temperature is 600 °C, the calcination time is 6 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing hexahydrate chloroplatinic acid and copper nitrate, with a mass ratio of Pt to Cu of 1:6. The immersion time is 6 h, and the sum of the mass of the precious metal and transition metal in the mixed solution is 5% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a helium atmosphere and calcined again at a temperature of 550 °C for 6 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 8 V, the electrolysis time was 8 h, the electrolysis temperature was 60 °C, and the stirring rate was 400 rpm. The catalyst after electrolysis was dried at 100 °C for 20 h to obtain a salt-resistant Pt-Cu / TiO2 catalyst. Embodiment 14

[0032] A method for preparing a salt-resistant Pt-Cu / CeO2 catalyst, the steps are as follows: (1) Pretreatment of metal oxide carrier: CeO2 was used as the carrier and acid-washed with a dilute nitric acid solution with a concentration of 0.2 mol / L. The ratio of the carrier to the solution was 1 g:50 mL, and the acid washing time was 5 h. (2) Salt washing: The pre-treated support was salt washed with a 3 wt % sodium chloride solution for 3 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and calcined at a temperature of 600 °C, a calcination time of 4 h, and a heating rate of 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing potassium chloroplatinate and copper nitrate, with a mass ratio of Pt to Cu of 1:6. The immersion time is 4 h, and the sum of the mass of the precious metal and transition metal in the mixed solution is 4% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and heated up for calcination again at a temperature of 550 °C for 4 h at a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 10 V, the electrolysis time was 8 h, the electrolysis temperature was 45 °C, and the stirring rate was 300 rpm. The catalyst after electrolysis was dried at 100 °C for 24 h to obtain a salt-resistant Pt-Cu / CeO2 catalyst. Embodiment 15

[0033] A method for preparing a salt-resistant Pd-W / TiO2 catalyst comprises the following steps: (1) Pretreatment of metal oxide carrier: TiO2 was used as the carrier and acid-washed with a dilute nitric acid solution with a concentration of 0.4 mol / L. The ratio of the carrier to the solution was 1 g:50 mL, and the acid washing time was 4 h. (2) Salt washing: The support after the above pretreatment was salt washed with 2 wt % sodium chloride solution for 4 h, and then thoroughly rinsed with deionized water; (3) First calcination treatment: the salt-washed carrier is placed in a nitrogen atmosphere and heated for calcination; the calcination temperature is 650 °C, the calcination time is 6 h, and the heating rate is 2 °C / min; (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing palladium nitrate and ammonium metatungstate, with a mass ratio of Pd to W of 1:8. The impregnation time is 3 h, and the sum of the mass of the precious metal and transition metal in the mixed solution is 2% of the support mass. (5) Second calcination treatment: The impregnated catalyst was placed in a nitrogen atmosphere and calcined again at a temperature of 600 °C, a calcination time of 4 h, and a heating rate of 2 °C / min. (6) Desalination treatment: The electrochemical desalination process using platinum electrodes and copper electrodes was used. The electrolyte was 0.5 mol / L sodium sulfate solution. The voltage was 5 V, the electrolysis time was 5 h, the electrolysis temperature was 50 °C, and the stirring rate was 400 rpm. The catalyst after electrolysis was dried at 100 °C for 12 h to obtain a salt-resistant Pd-W / TiO2 catalyst. Comparative Example 1

[0034] A method for preparing a Pt-Cu / Al2O3 catalyst. Compared with Example 1, steps (2) and (6) in Example 1 are omitted, and other processes and conditions are the same as those in Example 1. Comparative Examples 2-15

[0035] Compared with Example 2-15, steps (2) and (6) in each example are eliminated, and other processes and conditions are the same as those in Example 2-15.

[0036] 0.2 g of the catalysts prepared in Examples 1-7 and Comparative Examples 1-7 were respectively taken into a high-pressure reactor, and then 15 mL of 5 wt% of different reaction solutions and a certain concentration of sodium chloride solution were added to a 25 mL high-pressure reactor, and the reactor was evacuated three times with high-purity hydrogen. Finally, the reactor was filled with hydrogen to 2 MPa and sealed. The initial stirring speed was 200 rpm. The speed was increased to 1000 rpm after heating to 160 ° C and the timing was started. After the reaction was completed for 18 h, the solution components were analyzed by high performance liquid chromatography, and the conversion rate and selectivity were calculated. The specific results are shown in Tables 1 and 2.

[0037] Table 1

[0038] Table 2

[0039] 0.2 g of the catalysts prepared in Examples 8-15 and Comparative Examples 8-15 were taken respectively, and 15 mL of 5wt% different reaction solutions and a certain concentration of sodium chloride solution were taken respectively and added into a 25 mL high-pressure reactor. The reactor was evacuated three times with high-purity oxygen, and finally filled with oxygen to 1 MPa and the reactor was sealed. The initial stirring speed was 200 rpm. The speed was increased to 1000 rpm after heating to 70°C and the timing was started. After the reaction was completed for 10 h, the solution components were analyzed by high performance liquid chromatography, and the conversion rate and selectivity were calculated. The specific results are shown in Tables 3 and 4.

[0040] Table 3

[0041] Table 4

[0042] It can be seen from Tables 1-4 that the salt-resistant bimetallic supported catalyst synthesized by the method of the present invention solves the problem of deactivation of traditional catalysts in high-salt environments, significantly improves the catalytic efficiency, and has broad application prospects and high economic value.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a salt-resistant bimetallic supported catalyst, characterized in that: The following steps are involved: (1) Pretreatment of metal oxide carrier: pretreatment of the metal oxide carrier to remove impurities on the surface of the metal oxide; the metal oxide carrier is at least one of Al2O3, TiO2, CeO2, and ZrO2; (2) Salt washing: The pretreated metal oxide support is salt washed with a salt solution, and then washed with water to remove excess salt; (3) First calcination treatment: calcination treatment is carried out by heating under the protection of inert gas; (4) Impregnation treatment: impregnating the carrier after the first calcination in a mixed solution containing a noble metal salt and a transition metal salt, and drying after the impregnation to obtain a metal-loaded carrier; the noble metal salt is at least one of Pt, Pd, and Rh metal salts, and the transition metal salt is at least one of Cu and W metal salts; the elemental mass ratio of the noble metal to the transition metal is 1:1 to 1:10; the sum of the mass of the noble metal and the transition metal in the mixed solution is 2 to 7% of the mass of the carrier; (5) Second calcination treatment: heating the metal-loaded carrier for a second calcination treatment; (6) Desalination treatment: The electrochemical desalination process is used to remove the salt remaining on the surface, and the catalyst is taken out, washed and dried to obtain the salt-resistant bimetallic supported catalyst.

2. The method for preparing the salt-resistant bimetallic supported catalyst according to claim 1, characterized in that: The pretreatment in step (1) is acid washing or alkali washing; The pickling adopts a dilute nitric acid solution with a concentration of 0.1-1 mol / L; the ratio of the metal oxide support to the dilute nitric acid solution is 1 g: 30-80 mL; the pickling treatment time is 0.5-5 h; The alkali washing adopts a sodium hydroxide solution with a concentration of 0.5-2 mol / L; the ratio of the metal oxide carrier to the sodium hydroxide solution is 1 g: 20-40 mL; and the treatment time of the alkali washing is 0.5-5 h.

3. The method for preparing the salt-resistant bimetallic supported catalyst according to claim 1, characterized in that: The salt solution in step (2) is a sodium chloride solution with a concentration of 0.5-5wt%, and the salt washing treatment time is 0.5-10 h.

4. The method for preparing the salt-resistant bimetallic supported catalyst according to claim 1, characterized in that: In step (3), the inert gas is any one of nitrogen, helium and argon; the calcination temperature is 400-800°C, the time is 2-6 h; and the heating rate is 2-10°C / min.

5. The method for preparing the salt-resistant bimetallic supported catalyst according to claim 1, characterized in that: In step (4), the noble metal salt is at least one of chloroplatinic acid hexahydrate, potassium chloroplatinate, platinum nitrate, palladium nitrate, and rhodium chloride; and the transition metal salt is at least one of copper nitrate, ammonium metatungstate, and ammonium paratungstate.

6. The method for preparing the salt-resistant bimetallic supported catalyst according to claim 1, characterized in that: The drying temperature in step (4) is 80-120°C and the drying time is 12-24 hours.

7. The method for preparing the salt-resistant bimetallic supported catalyst according to claim 1, characterized in that: In step (5), the second calcination temperature is 300-600°C, and the time is 2-6 h; the heating rate is 2-10°C / min; and the second calcination temperature is lower than the first calcination temperature.

8. The method for preparing the salt-resistant bimetallic supported catalyst according to claim 1, characterized in that: In the electrochemical desalination device of step (6), the anode material is a platinum electrode, the cathode material is a copper electrode, and the electrolyte solution is a 0.5 mol / L sodium sulfate solution; the voltage of the electrochemical desalination device is 3-10 V, the electrolysis time is 2-8 h, the electrolysis temperature is 20-60 °C, and the stirring rate is 100-500 rpm; The drying temperature in step (6) is 80-100°C; the drying time is 12-24 hours.

9. Use of a catalyst prepared by the method according to any one of claims 1 to 8, characterized in that: The catalyst is used for hydrogenation or oxidation reaction of polyols in an aqueous phase, wherein the polyols are at least one of glycerol, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glucose, mannose, and xylose; The reaction temperature is 50-200°C, the reaction time is 0.5-48 h, and the reaction pressure is 0.1-4.0 MPa.

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