Preparation method of a salt-resistant bimetal-loaded catalyst and its application in polyol hydrogenation or oxidation reaction

Abstract

The present invention provides a method for preparing a salt-resistant bimetallic supported catalyst and its application in the hydrogenation or oxidation reaction of polyols, belonging to the technical field of catalysts. The preparation process of the present invention includes metal oxide support pretreatment, salt washing treatment, first roasting treatment, impregnation treatment, second roasting treatment and desalination treatment. The present invention successfully removes residual salt on the surface of the catalyst by accurately controlling the conditions of each step and adopts an electrochemical desalination process, thereby improving the stability and activity of the catalyst in a high-salt environment. The bimetallic supported catalyst prepared by the present invention can be effectively applied to the hydrogenation and oxidation reactions of polyols, and has significant salt resistance, excellent catalytic efficiency and long-term stability. The catalyst of the present invention has a high reaction conversion rate and selectivity, and exhibits a stronger anti-degradation ability in a high salt concentration environment, solving the technical problem that the existing catalyst fails in a salt environment.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly to a preparation method of a salt-resistant bimetal-supported catalyst and its application in the hydrogenation or oxidation reaction of polyols. Background Art

[0002] Polyols (such as glycerol, ethylene glycol, propylene glycol, etc.) are important chemical raw materials and have wide applications in the 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, traditional catalysts experience a decline in activity and a decrease in catalytic efficiency in a high-salt environment, which limits their application in certain industrial processes.

[0003] Existing catalysts use metal oxides (such as Al 2 O 3 , TiO 2 , etc.) as carriers and load active metals through methods such as metal impregnation and calcination. However, traditional supported catalysts are easily affected by salt ions in a high-salt environment, resulting in the coverage of active sites on the catalyst surface by salts, thereby causing the catalyst to lose activity and a significant decrease in catalytic efficiency. In addition, in the preparation process of existing catalysts, insufficient attention has been paid to the removal of surface salts of the catalyst. Usually, simple physical washing methods are used to remove residual salts, but these methods are often inefficient and cannot completely remove the salts, resulting in a significant decline in the activity and stability of the catalyst. Therefore, there is an urgent need 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 preparation method of a salt-resistant bimetal-supported catalyst. Through the synergistic effect of a metal oxide carrier and noble metals and transition metals, and by using an innovative pretreatment and desalting process, the stability and activity of the catalyst in a high-salt concentration environment are significantly improved, providing a new solution for the hydrogenation and oxidation reactions of polyols.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A preparation method of a salt-resistant bimetal-supported catalyst, comprising the following steps:

[0007] (1) Pretreatment of the metal oxide carrier: Pretreat the metal oxide carrier to remove impurities on the surface of the metal oxide; the metal oxide carrier is at least one of Al 2 O 3 , TiO 2 , CeO 2 , ZrO 2 ; this step can improve the surface characteristics of the carrier and enhance the dispersion and stability of the catalyst;

[0008] (2) Salt washing treatment: The pretreated metal oxide support is subjected to salt washing treatment with a salt solution, and then washed with water to remove excess salts; the salt washing treatment is carried out by washing with a salt solution of a specific concentration to remove possible dissolved salts and impurities, further improving the salt resistance of the catalyst.

[0009] (3) First calcination treatment: The temperature is raised for calcination treatment under the protection of an inert gas.

[0010] (4) Impregnation treatment: The support after the first calcination is impregnated in a mixed solution containing a noble metal salt and a transition metal salt, and after impregnation, it is dried to obtain a support loaded with metals; 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 masses of the noble metal and the transition metal in the mixed solution is 2 to 7% of the mass of the support; the noble metal is responsible for the main activity of the catalytic reaction, while the transition metal provides an auxiliary effect to enhance the durability and salt resistance of the catalyst.

[0011] (5) Second calcination treatment: The temperature is raised for the second calcination treatment of the support loaded with metals.

[0012] (6) Desalting treatment: An electrochemical desalting process is used to remove the residual salts on the surface, and after taking out, it is washed and dried to obtain the salt-resistant bimetal-loaded catalyst.

[0013] Preferably, the pretreatment in step (1) is pickling or alkali washing.

[0014] The pickling is carried out with a dilute nitric acid solution with a concentration of 0.1 to 1 mol / L; the ratio of the metal oxide support to the dilute nitric acid solution is 1 g: 30 to 80 mL; the treatment time of the pickling is 0.5 to 5 h.

[0015] The alkali washing is carried out with a sodium hydroxide solution with a concentration of 0.5 to 2 mol / L; the ratio of the metal oxide support to the sodium hydroxide solution is 1 g: 20 to 40 mL; the treatment time of the alkali washing is 0.5 to 5 h.

[0016] Preferably, the salt solution in step (2) is a sodium chloride solution with a concentration of 0.5 to 5 wt%, and the treatment time of the salt washing treatment is 0.5 to 10 h.

[0017] Preferably, the inert gas in step (3) is any one of nitrogen, helium, and argon; the calcination temperature is 400 to 800 °C, the time is 2 to 6 h; the heating rate is 2 to 10 °C / min.

[0018] Preferably, the noble metal salt in step (4) is at least one of chloroplatinic acid hexahydrate, potassium chloroplatinate, platinum nitrate, palladium nitrate, and rhodium chloride; the transition metal salt is at least one of copper nitrate, ammonium metatungstate, and ammonium paratungstate.

[0019] Preferably, the drying temperature in step (4) is 80 - 120 °C, and the time is 12 - 24 h.

[0020] 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; the temperature of the second calcination is lower than that of the first calcination.

[0021] Preferably, in the electrochemical desalination device in 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;

[0022] The drying temperature in step (6) is 80 - 100 °C; the drying time is 12 - 24 h.

[0023] Another object of the present invention is to provide a use of the catalyst prepared by the above method, the catalyst is used for the hydrogenation or oxidation reaction of polyols in an aqueous phase, the polyol is at least one of glycerol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol or saccharides containing multiple hydroxyl groups, and the saccharides containing multiple hydroxyl groups include any one of glucose, mannose, and xylose;

[0024] The temperature of the reaction is 50 - 200 °C, the reaction time is 0.5 - 48 h, and the reaction pressure is 0.1 - 4.0 MPa.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) Excellent salt resistance: Through the innovative electrochemical desalination process, the present invention can effectively remove the residual salts on the surface of the catalyst, significantly improve the stability and catalytic activity of the catalyst in a high-salt concentration environment, and solve the problem of the activity decline of traditional catalysts in a salt environment.

[0027] (2) Improved catalytic efficiency and long-term stability: The prepared catalyst exhibits excellent catalytic efficiency in the hydrogenation and oxidation reactions of polyols, and shows high conversion and high selectivity for a long time in a high-salt environment, which is significantly better than existing catalysts and has high long-term operation stability.

[0028] (3)Innovative electrochemical desalination process: Through the electrochemical desalination method, the salts on the catalyst surface are precisely removed, avoiding the limitations of traditional physical washing methods, ensuring the maximum exposure of the catalyst active sites, and enhancing the service life and economy of the catalyst. Detailed implementation manners

[0029] The present invention will be further described below in conjunction with embodiments. Embodiment 1

[0030] A salt-resistant Pt-Cu / Al 2 O 3 catalyst preparation method, the steps are as follows:

[0031] (1)Pretreatment of metal oxide support: Using Al 2 O 3 as the support, pickling it with a dilute nitric acid solution with a concentration of 0.5 mol / L, the ratio of the support to the solution is 1g:50 mL, and the pickling time is 2 h;

[0032] (2)Salt washing treatment: Using a 0.5wt% sodium chloride solution to wash the support pretreated above, the washing time is 8 h, and then thoroughly washing with deionized water;

[0033] (3)First calcination treatment: Placing the salt-washed support in a nitrogen atmosphere and heating it for calcination; the calcination temperature is 600 °C, the calcination time is 4 h, and the heating rate is 2 °C / min;

[0034] (4)Impregnation treatment: Immersing the calcined support in a mixed solution containing platinum nitrate and copper nitrate, the mass ratio of Pt to Cu elements is 1:5, the impregnation time is 4 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 3% of the mass of the support;

[0035] (5)Second calcination treatment: Placing the impregnated catalyst in a nitrogen atmosphere and heating it again for calcination, the calcination temperature is 450 °C, the calcination time is 3 h, and the heating rate is 2 °C / min;

[0036] (6)Desalination treatment: Adopting an electrochemical desalination process with platinum electrodes and copper electrodes, the electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 5 V, the electrolysis time is 4 h, the electrolysis temperature is 40 °C, the stirring rate is 300 rpm, drying the electrolyzed catalyst, the drying temperature is 100 °C, and the drying time is 12 h, thus obtaining the salt-resistant Pt-Cu / Al 2 O 3 catalyst. Embodiment 2

[0037] A salt-resistant Pt-W / Al2 O 3 Method for preparing catalyst, steps are as follows:

[0038] (1) Pretreatment of metal oxide support: Using Al 2 O 3 as the support, pickling it with a dilute nitric acid solution with a concentration of 0.3 mol / L, the ratio of the support to the solution is 1 g:60 mL, and the pickling time is 4 h;

[0039] (2) Salt washing treatment: Using a 2 wt% sodium chloride solution to wash the support after the above pretreatment, the washing time is 10 h, and then thoroughly washing with deionized water;

[0040] (3) First calcination treatment: Placing the support after salt washing 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;

[0041] (4) Impregnation treatment: Immersing the support after calcination in a mixed solution containing potassium chloroplatinate and ammonium metatungstate, the mass ratio of Pt to W elements is 1:4, the impregnation time is 2 h, and the sum of the mass of the noble metal and the transition metal in the mixed solution is 6% of the mass of the support;

[0042] (5) Second calcination treatment: Placing the impregnated catalyst in a nitrogen atmosphere and heating it again for calcination, the calcination temperature is 350 °C, the calcination time is 4 h, and the heating rate is 2 °C / min;

[0043] (6) Desalting treatment: Using an electrochemical desalting process with platinum electrodes and copper electrodes, the electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 6 V, the electrolysis time is 6 h, the electrolysis temperature is 40 °C, the stirring rate is 500 rpm, drying the electrolyzed catalyst, the drying temperature is 100 °C, and the drying time is 18 h, thus obtaining the salt-resistant Pt-W / Al 2 O 3 catalyst. Example 3

[0044] Method for preparing a salt-resistant Pd-W / ZrO 2 catalyst, steps are as follows:

[0045] (1) Pretreatment of metal oxide support: Using ZrO 2 as the support, alkali washing it with a sodium hydroxide solution with a concentration of 1.5 mol / L, the ratio of the support to the solution is 1 g:40 mL, and the alkali washing time is 5 h;

[0046] (2) Salt washing treatment: The carrier after the above pretreatment was washed with a 0.5 wt% sodium chloride solution for 10 h, and then thoroughly washed with deionized water;

[0047] (3) First calcination treatment: The salt-washed carrier was placed in an argon atmosphere and calcined by heating; the calcination temperature was 500 °C, the calcination time was 5 h, and the heating rate was 2 °C / min;

[0048] (4) Impregnation treatment: The calcined carrier was impregnated in a mixed solution containing palladium nitrate and ammonium metatungstate, and the mass ratio of Pd to W elements was 1:3. The impregnation time was 3 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution was 4% of the mass of the carrier;

[0049] (5) Second calcination treatment: The impregnated catalyst was placed in an argon atmosphere and calcined again by heating. The calcination temperature was 450 °C, the calcination time was 4 h, and the heating rate was 2 °C / min;

[0050] (6) Desalting treatment: An electrochemical desalting process using a platinum electrode and a copper electrode was adopted. The electrolyte was a 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 electrolyzed catalyst was dried at a drying temperature of 90 °C for 12 h to obtain the salt-resistant Pd-W / ZrO 2 catalyst. Example 4

[0051] A preparation method of a salt-resistant Pt-W / CeO 2 catalyst is as follows:

[0052] (1) Pretreatment of metal oxide carrier: Using CeO 2 as the carrier, it was pickled with a 0.2 mol / L dilute nitric acid solution. The ratio of the carrier to the solution was 1 g:80 mL, and the pickling time was 5 h;

[0053] (2) Salt washing treatment: The carrier after the above pretreatment was washed with a 1.5 wt% sodium chloride solution for 4 h, and then thoroughly washed with deionized water;

[0054] (3) First calcination treatment: The salt-washed carrier was placed in a nitrogen atmosphere and calcined by heating; the calcination temperature was 650 °C, the calcination time was 6 h, and the heating rate was 5 °C / min;

[0055] (4) Impregnation treatment: Immerse the calcined support in a mixed solution containing chloroplatinic acid hexahydrate and ammonium paratungstate. The mass ratio of Pt to W elements is 1:8, the impregnation time is 4 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 5% of the mass of the support;

[0056] (5) Second calcination treatment: Place the impregnated catalyst in a nitrogen atmosphere, heat up and calcine again. The calcination temperature is 550 °C, the calcination time is 6 h, and the heating rate is 5 °C / min;

[0057] (6) Desalting treatment: Adopt an electrochemical desalting process with platinum electrodes and copper electrodes. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 6 V, the electrolysis time is 6 h, the electrolysis temperature is 40 °C, the stirring rate is 500 rpm. Dry the electrolyzed catalyst, the drying temperature is 100 °C, and the drying time is 18 h, then the salt-resistant Pt-W / CeO 2 catalyst is obtained. Example 5

[0058] A preparation method of a salt-resistant Pt-W / ZrO 2 catalyst is as follows:

[0059] (1) Pretreatment of metal oxide support: Using ZrO 2 as the support, pickling it with a dilute nitric acid solution with a concentration of 0.2 mol / L. The ratio of the support to the solution is 1 g:60 mL, and the pickling time is 5 h;

[0060] (2) Salt washing treatment: Wash the above pretreated support with a 4wt% sodium chloride solution for 4 h, and then thoroughly wash it with deionized water;

[0061] (3) First calcination treatment: Place the salt-washed support in a helium atmosphere, heat up and calcine. The calcination temperature is 650 °C, the calcination time is 6 h, and the heating rate is 2 °C / min;

[0062] (4) Impregnation treatment: Immerse the calcined support in a mixed solution containing platinum nitrate and ammonium metatungstate. The mass ratio of Pt to W elements is 1:8, the impregnation time is 4 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 5% of the mass of the support;

[0063] (5) Second calcination treatment: Place the impregnated catalyst in a helium atmosphere, heat up and calcine again. The calcination temperature is 550 °C, the calcination time is 6 h, and the heating rate is 2 °C / min;

[0064] (6) Desalination treatment: An electrochemical desalination process using a platinum electrode and a copper electrode is adopted. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 6 V, the electrolysis time is 6 h, the electrolysis temperature is 40 °C, the stirring rate is 500 rpm. The electrolyzed catalyst is dried, the drying temperature is 100 °C, and the drying time is 20 h, thus obtaining the salt-resistant Pt-W / ZrO 2 catalyst. Example 6

[0065] A method for preparing a salt-resistant Pt-Cu / ZrO 2 catalyst is as follows:

[0066] (1) Pretreatment of metal oxide support: Using ZrO 2 as the support, it is pickled with a 0.8 mol / L dilute nitric acid solution. The ratio of the support to the solution is 1 g:80 mL, and the pickling time is 2 h;

[0067] (2) Salt washing treatment: The above pretreated support is salt washed with a 5 wt% sodium chloride solution, the washing time is 10 h, and then it is thoroughly washed with deionized water;

[0068] (3) First calcination treatment: The salt-washed support 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;

[0069] (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing potassium chloroplatinate and copper nitrate. The mass ratio of Pt to Cu elements is 1:10, the impregnation time is 2 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 6% of the mass of the support;

[0070] (5) Second calcination treatment: The impregnated catalyst is placed in a nitrogen atmosphere and heated again for calcination. The calcination temperature is 600 °C, the calcination time is 6 h, and the heating rate is 2 °C / min;

[0071] (6) Desalination treatment: An electrochemical desalination process using a platinum electrode and a copper electrode is adopted. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 4 V, the electrolysis time is 6 h, the electrolysis temperature is 55 °C, the stirring rate is 500 rpm. The electrolyzed catalyst is dried, the drying temperature is 100 °C, and the drying time is 12 h, thus obtaining the salt-resistant Pt-Cu / ZrO 2 catalyst. Example 7

[0072] A salt-resistant Pd-W / Al 2 O 3The preparation method of the catalyst is as follows:

[0073] (1)Pretreatment of the metal oxide support: Using Al 2 O 3 as the support, pickling it with a dilute nitric acid solution with a concentration of 0.5 mol / L. The ratio of the support to the solution is 1 g:30 mL, and the pickling time is 1.5 h;

[0074] (2)Salt washing treatment: Using a 3wt% sodium chloride solution to wash the support pretreated above, the washing time is 6 h, and then thoroughly washing with deionized water;

[0075] (3)First calcination treatment: Placing the salt-washed support in a nitrogen atmosphere and heating it for calcination; the calcination temperature is 600 °C, the calcination time is 5 h, and the heating rate is 2 °C / min;

[0076] (4)Impregnation treatment: Impregnating the calcined support in a mixed solution containing palladium nitrate and ammonium metatungstate. The mass ratio of Pd to W elements is 1:4, the impregnation time is 3 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 4% of the mass of the support;

[0077] (5)Second calcination treatment: Placing the impregnated catalyst in a nitrogen atmosphere and heating it again for calcination. The calcination temperature is 500 °C, the calcination time is 5 h, and the heating rate is 2 °C / min;

[0078] (6)Desalting treatment: Adopting an electrochemical desalting process with platinum electrodes and copper electrodes. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 6 V, the electrolysis time is 4 h, the electrolysis temperature is 60 °C, the stirring rate is 200 rpm. Drying the electrolyzed catalyst, the drying temperature is 100 °C, and the drying time is 18 h, thus obtaining the salt-resistant Pd-W / Al 2 O 3 catalyst. Example 8

[0079] A preparation method of a salt-resistant Pd-Cu / CeO 2 catalyst is as follows:

[0080] (1)Pretreatment of the metal oxide support: Using CeO 2 as the support, washing it with a sodium hydroxide solution with a concentration of 0.5 mol / L. The ratio of the support to the solution is 1 g:30 mL, and the alkali washing time is 2 h;

[0081] (2)Salt washing treatment: Using a 0.5wt% sodium chloride solution to wash the support pretreated above, the washing time is 10 h, and then thoroughly washing with deionized water;

[0082] (3) First calcination treatment: Place the salt-washed support in a nitrogen atmosphere and heat it up for calcination; the calcination temperature is 600 °C, the calcination time is 4 h, and the heating rate is 2 °C / min;

[0083] (4) Impregnation treatment: Immerse the calcined support in a mixed solution containing palladium nitrate and copper nitrate. The mass ratio of Pd to Cu elements is 1:5, the impregnation time is 4 h, and the sum of the masses of precious metals and transition metals in the mixed solution is 3% of the mass of the support;

[0084] (5) Second calcination treatment: Place the impregnated catalyst in a nitrogen atmosphere and heat it up again for calcination. The calcination temperature is 450 °C, the calcination time is 3 h, and the heating rate is 2 °C / min;

[0085] (6) Desalting treatment: Adopt an electrochemical desalting process using platinum electrodes and copper electrodes. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 5 V, the electrolysis time is 4 h, the electrolysis temperature is 40 °C, the stirring rate is 300 rpm. Dry the electrolyzed catalyst, the drying temperature is 100 °C, and the drying time is 12 h, then the salt-resistant Pd-Cu / CeO 2 catalyst is obtained. Example 9

[0086] A preparation method of a salt-resistant Pt-W / TiO 2 catalyst, the steps are as follows:

[0087] (1) Pretreatment of metal oxide support: Using TiO 2 as the support, use a 1 mol / L sodium hydroxide solution to perform alkali washing on it. The ratio of the support to the solution is 1 g:20 mL, and the alkali washing time is 3 h;

[0088] (2) Salt washing treatment: Use a 1wt% sodium chloride solution to wash the above pretreated support. The washing time is 8 h, and then thoroughly wash it with deionized water;

[0089] (3) First calcination treatment: Place the salt-washed support in an argon atmosphere and heat it up for calcination; the calcination temperature is 550 °C, the calcination time is 6 h, and the heating rate is 2 °C / min;

[0090] (4) Impregnation treatment: Immerse the calcined support in a mixed solution containing potassium chloroplatinate and ammonium paratungstate. The mass ratio of Pt to W elements is 1:6, the impregnation time is 5 h, and the sum of the masses of precious metals and transition metals in the mixed solution is 2% of the mass of the support;

[0091] (5) Second calcination treatment: Place the impregnated catalyst in a nitrogen atmosphere, heat it up and calcine it again. The calcination temperature is 500 °C, the calcination time is 6 h, and the heating rate is 2 °C / min;

[0092] (6) Desalting treatment: Adopt an electrochemical desalting process with a platinum electrode and a copper electrode. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 5 V, the electrolysis time is 4 h, the electrolysis temperature is 40 °C, and the stirring rate is 500 rpm. Dry the electrolyzed catalyst. The drying temperature is 100 °C and the drying time is 12 h, thus obtaining the salt-resistant Pt-W / TiO 2 catalyst. Example 10

[0093] A preparation method of a salt-resistant Pd-Cu / Al 2 O 3 catalyst, the steps are as follows:

[0094] (1) Pretreatment of the metal oxide support: Using Al 2 O 3 as the support, pickling it with a dilute nitric acid solution with a concentration of 0.7 mol / L. The ratio of the support to the solution is 1 g:70 mL, and the pickling time is 4 h;

[0095] (2) Salt washing treatment: Use a 3wt% sodium chloride solution to wash the support after the above pretreatment. The washing time is 5 h, and then wash it thoroughly with deionized water;

[0096] (3) First calcination treatment: Place the salt-washed support in a nitrogen atmosphere, heat it up and calcine it. The calcination temperature is 700 °C, the calcination time is 5 h, and the heating rate is 5 °C / min;

[0097] (4) Impregnation treatment: Immerse the calcined support in a mixed solution containing palladium nitrate and copper nitrate. The mass ratio of Pd to Cu elements is 1:6, the impregnation time is 4 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 5% of the mass of the support;

[0098] (5) Second calcination treatment: Place the impregnated catalyst in a nitrogen atmosphere, heat it up and calcine it again. The calcination temperature is 600 °C, the calcination time is 5 h, and the heating rate is 5 °C / min;

[0099] (6) Desalination treatment: An electrochemical desalination process using platinum electrodes and copper electrodes is adopted. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 8 V, the electrolysis time is 4 h, the electrolysis temperature is 50 °C, the stirring rate is 300 rpm. The electrolyzed catalyst is dried, the drying temperature is 100 °C, and the drying time is 18 h, thus obtaining the salt-resistant Pd-Cu / Al 2 O 3 catalyst. Example 11

[0100] A preparation method of a salt-resistant Pd-Cu / ZrO 2 catalyst is as follows:

[0101] (1) Pretreatment of metal oxide support: Using ZrO 2 as the support, it is pickled with a 0.5 mol / L dilute nitric acid solution. The ratio of the support to the solution is 1 g:50 mL, and the pickling time is 1 h;

[0102] (2) Salt washing treatment: The above pretreated support is salt washed with a 2.5 wt% sodium chloride solution, the washing time is 2 h, and then it is thoroughly washed with deionized water;

[0103] (3) First calcination treatment: The salt-washed support 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;

[0104] (4) Impregnation treatment: The calcined support is impregnated in a mixed solution containing palladium nitrate and copper nitrate. The mass ratio of Pd to Cu elements is 1:4, the impregnation time is 3 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 3% of the mass of the support;

[0105] (5) Second calcination treatment: The impregnated catalyst is placed in a nitrogen atmosphere and heated again for calcination. The calcination temperature is 600 °C, the calcination time is 5 h, and the heating rate is 2 °C / min;

[0106] (6) Desalination treatment: An electrochemical desalination process using platinum electrodes and copper electrodes is adopted. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 5 V, the electrolysis time is 5 h, the electrolysis temperature is 60 °C, the stirring rate is 100 rpm. The electrolyzed catalyst is dried, the drying temperature is 80 °C, and the drying time is 24 h, thus obtaining the salt-resistant Pd-Cu / ZrO 2 catalyst. Example 12

[0107] A salt-resistant Pd-Cu / TiO 2The preparation method of the catalyst is as follows:

[0108] (1)Pretreatment of the metal oxide support: Using TiO 2 as the support, pickling it with a dilute nitric acid solution with a concentration of 1 mol / L. The ratio of the support to the solution is 1 g:30 mL, and the pickling time is 3 h;

[0109] (2)Salt washing treatment: Using a 2wt% sodium chloride solution to wash the support pretreated above, the washing time is 4 h, and then thoroughly washing with deionized water;

[0110] (3)First calcination treatment: Placing the salt-washed support in a nitrogen atmosphere and heating it for calcination; the calcination temperature is 600 °C, the calcination time is 5 h, and the heating rate is 2 °C / min;

[0111] (4)Impregnation treatment: Immersing the calcined support in a mixed solution containing palladium nitrate and copper nitrate. The mass ratio of Pd to Cu elements is 1:8, the impregnation time is 4 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 3% of the mass of the support;

[0112] (5)Second calcination treatment: Placing the impregnated catalyst in a nitrogen atmosphere and heating it again for calcination. The calcination temperature is 550 °C, the calcination time is 5 h, and the heating rate is 2 °C / min;

[0113] (6)Desalting treatment: Adopting an electrochemical desalting process with platinum electrodes and copper electrodes. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 8 V, the electrolysis time is 8 h, the electrolysis temperature is 45 °C, the stirring rate is 500 rpm. Drying the electrolyzed catalyst, the drying temperature is 100 °C, and the drying time is 24 h, thus obtaining the salt-resistant Pd-Cu / TiO 2 catalyst. Example 13

[0114] A preparation method of a salt-resistant Pt-Cu / TiO 2 catalyst is as follows:

[0115] (1)Pretreatment of the metal oxide support: Using TiO 2 as the support, pickling it with a dilute nitric acid solution with a concentration of 0.4 mol / L. The ratio of the support to the solution is 1 g:40 mL, and the pickling time is 4 h;

[0116] (2)Salt washing treatment: Using a 5wt% sodium chloride solution to wash the support pretreated above, the washing time is 5 h, and then thoroughly washing with deionized water;

[0117] (3) First calcination treatment: Place the carrier after salt washing in a helium atmosphere and raise the temperature for calcination; the calcination temperature is 600 °C, the calcination time is 6 h, and the heating rate is 2 °C / min;

[0118] (4) Impregnation treatment: Immerse the calcined carrier in a mixed solution containing chloroplatinic acid hexahydrate and copper nitrate. The mass ratio of Pt to Cu elements is 1:6, the impregnation time is 6 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 5% of the mass of the carrier;

[0119] (5) Second calcination treatment: Place the impregnated catalyst in a helium atmosphere and raise the temperature for re-calcination. The calcination temperature is 550 °C, the calcination time is 6 h, and the heating rate is 2 °C / min;

[0120] (6) Desalting treatment: Adopt an electrochemical desalting process with platinum electrodes and copper electrodes. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 8 V, the electrolysis time is 8 h, the electrolysis temperature is 60 °C, the stirring rate is 400 rpm. Dry the electrolyzed catalyst, the drying temperature is 100 °C, and the drying time is 20 h, then the salt-resistant Pt-Cu / TiO 2 catalyst is obtained. Example 14

[0121] A preparation method of a salt-resistant Pt-Cu / CeO 2 catalyst is as follows:

[0122] (1) Pretreatment of metal oxide carrier: Using CeO 2 as the carrier, pickling it with a dilute nitric acid solution with a concentration of 0.2 mol / L. The ratio of the carrier to the solution is 1 g:50 mL, and the pickling time is 5 h;

[0123] (2) Salt washing treatment: Use a 3wt% sodium chloride solution to wash the carrier after the above pretreatment. The washing time is 3 h, and then thoroughly wash it with deionized water;

[0124] (3) First calcination treatment: Place the carrier after salt washing in a nitrogen atmosphere and raise the temperature for calcination; the calcination temperature is 600 °C, the calcination time is 4 h, and the heating rate is 2 °C / min;

[0125] (4) Impregnation treatment: Immerse the calcined carrier in a mixed solution containing potassium chloroplatinate and copper nitrate. The mass ratio of Pt to Cu elements is 1:6, the impregnation time is 4 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 4% of the mass of the carrier;

[0126] (5) Second calcination treatment: Place the impregnated catalyst in a nitrogen atmosphere, heat it up and calcine it again. The calcination temperature is 550 °C, the calcination time is 4 h, and the heating rate is 2 °C / min;

[0127] (6) Desalination treatment: Adopt an electrochemical desalination process with platinum electrodes and copper electrodes. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 10 V, the electrolysis time is 8 h, the electrolysis temperature is 45 °C, and the stirring rate is 300 rpm. Dry the electrolyzed catalyst. The drying temperature is 100 °C and the drying time is 24 h, thus obtaining the salt-resistant Pt-Cu / CeO 2 catalyst. Example 15

[0128] A preparation method of a salt-resistant Pd-W / TiO 2 catalyst is as follows:

[0129] (1) Pretreatment of metal oxide support: Using TiO 2 as the support, pickle it with a dilute nitric acid solution with a concentration of 0.4 mol / L. The ratio of the support to the solution is 1 g:50 mL, and the pickling time is 4 h;

[0130] (2) Salt washing treatment: Wash the above pretreated support with a 2wt% sodium chloride solution for 4 h, and then thoroughly wash it with deionized water;

[0131] (3) First calcination treatment: Place the salt-washed support in a nitrogen atmosphere and heat it up for calcination; the calcination temperature is 650 °C, the calcination time is 6 h, and the heating rate is 2 °C / min;

[0132] (4) Impregnation treatment: Immerse the calcined support in a mixed solution containing palladium nitrate and ammonium metatungstate. The mass ratio of Pd to W elements is 1:8, the impregnation time is 3 h, and the sum of the masses of the noble metal and the transition metal in the mixed solution is 2% of the mass of the support;

[0133] (5) Second calcination treatment: Place the impregnated catalyst in a nitrogen atmosphere, heat it up and calcine it again. The calcination temperature is 600 °C, the calcination time is 4 h, and the heating rate is 2 °C / min;

[0134] (6) Desalination treatment: Adopt an electrochemical desalination process with platinum electrodes and copper electrodes. The electrolyte is a 0.5 mol / L sodium sulfate solution, the voltage is 5 V, the electrolysis time is 5 h, the electrolysis temperature is 50 °C, and the stirring rate is 400 rpm. Dry the electrolyzed catalyst. The drying temperature is 100 °C and the drying time is 12 h, thus obtaining the salt-resistant Pd-W / TiO 2 catalyst. Comparative Example 1

[0135] A preparation method of Pt-Cu / Al 2 O 3 catalyst. Compared with Example 1, step (2) and step (6) in Example 1 were cancelled, and other processes and conditions were the same as those in Example 1.

[0136] Comparative Examples 2-15

[0137] Compared with Examples 2-15, step (2) and step (6) in each example were cancelled, and other processes and conditions were the same as those in Examples 2-15.

[0138] 0.2 g of the catalysts prepared in Examples 1-7 and Comparative Examples 1-7 were respectively taken into a high-pressure reactor. Then, 15 mL of different reaction solutions with a concentration of 5wt% and a certain concentration of sodium chloride solution were added to the 25 mL high-pressure reactor. The reactor was purged with high-purity hydrogen three times, and finally hydrogen was filled to 2 MPa and the reactor was sealed. The initial stirring speed was 200 rpm. The temperature was heated to 160 °C, the rotation speed was increased to 1000 rpm and timing was started. After 18 h of reaction, the composition of the solution was analyzed by high-performance liquid chromatography, and the conversion rate and selectivity were calculated. The specific results are shown in Table 1 and Table 2.

[0139] Table 1

[0140]

[0141] Table 2

[0142]

[0143] 0.2 g of the catalysts prepared in Examples 8-15 and Comparative Examples 8-15 were respectively taken. 15 mL of different reaction solutions with a concentration of 5wt% and a certain concentration of sodium chloride solution were respectively added to the 25 mL high-pressure reactor. The reactor was purged with high-purity oxygen three times, and finally oxygen was filled to 1 MPa and the reactor was sealed. The initial stirring speed was 200 rpm. The temperature was heated to 70 °C, the rotation speed was increased to 1000 rpm and timing was started. After 10 h of reaction, the composition of the solution was analyzed by high-performance liquid chromatography, and the conversion rate and selectivity were calculated. The specific results are shown in Table 3 and Table 4.

[0144] Table 3

[0145]

[0146] Table 4

[0147]

[0148] As can be seen from Table 1-4, 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.

[0149] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope 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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