CN117244543A - A titanium dioxide supported PdRu bimetallic catalyst and its preparation method and application - Google Patents

Abstract

The invention relates to a titanium dioxide-loaded PdRu bimetallic catalyst and its preparation method and application, and belongs to the technical fields of environmental catalysis and air pollution control. In this catalyst, titanium dioxide is used as a carrier, the precious metal Pd is the main active component, and Ru is the secondary active component that exerts a synergistic effect. Its characteristic is that the activity of the PdRu bimetallic catalyst for the selective catalytic reduction of NO _x by hydrogen under oxygen-rich conditions is significantly higher than that of a single Pd catalyst and a Ru catalyst. When the titanium dioxide-loaded PdRu bimetallic catalyst prepared by the invention has a space velocity of 52000h ^-1 , the purification efficiency of _NOx reaches 55-87% in a wide temperature range of 125-300°C.

Description

A titanium dioxide supported PdRu bimetallic catalyst and its preparation method and application

Technical field

The invention relates to a titanium dioxide-loaded PdRu bimetallic catalyst and its preparation method and application. In particular, it relates to a _TiO2- loaded PdRu bimetallic catalyst for the selective catalytic reduction of _NOx by hydrogen and its preparation method and application. It is suitable for hydrogen fuel. The elimination of _NOx under medium and low temperature conditions in motor vehicle and industrial boiler flue gases belongs to the technical fields of environmental catalysis and air pollution control.

Background technique

At present, ammonia selective catalytic reduction (NH ₃ -SCR) technology has been applied in diesel vehicle exhaust purification, but the leakage of reducing agent NH ₃ can easily cause air pollution. With the urgent need to reduce greenhouse gas _CO2 emissions, motor vehicles using hydrogen as fuel are increasingly attracting attention from academia and industry. Motor vehicles using hydrogen as fuel still produce NO _x . For the removal of NO _x emissions, the ideal technical route is hydrogen selective catalytic reduction (H ₂ -SCR). Compared with NH ₃ as a reducing agent, the reduction temperature of NO _x is greatly reduced when hydrogen is used as a reducing agent, and excess hydrogen reacts with oxygen to generate water, which will not cause secondary pollution.

Currently, the main problems with H ₂ -SCR denitration catalysts are the narrow temperature window and the conversion rate of NO _x that needs to be improved. The development of H ₂ -SCR denitration catalysts with high activity and wide temperature window can effectively control NO _x emitted by hydrogen fuel vehicles, which is of great significance for the promotion and application of hydrogen fuel vehicles.

The invention provides a TiO ₂ supported PdRu bimetallic catalyst with good performance for H ₂ -SCR denitration in a wide temperature range and a preparation method thereof.

Contents of the invention

The invention provides a titanium dioxide-supported PdRu bimetallic catalyst and its preparation method and application, belonging to the technical fields of environmental catalysis and air pollution control. In this catalyst, titanium dioxide is used as a carrier, the precious metal Pd is the main active component, and Ru is the secondary active component that exerts a synergistic effect. Its characteristic is that the H ₂ -SCR denitration activity of the PdRu bimetallic catalyst is significantly higher than that of the single Pd catalyst and Ru catalyst. When the titanium dioxide-loaded PdRu bimetallic catalyst prepared by the invention has a space velocity of 52000h ^-1 , the purification efficiency of _NOx reaches 55-87% in a wide temperature range of 125-300°C.

The purpose of the present invention is to provide a TiO ₂ supported PdRu bimetallic catalyst with a simple preparation method and high activity for H ₂ -SCR denitration and its preparation method. Through the synergistic effect between Pd and Ru, the H ₂ -SCR denitration performance of the catalyst is significantly improved, achieving efficient removal of NO _x within a wide temperature window.

The purpose of the present invention is achieved through the following technical solutions:

In a first aspect, the present invention provides a titanium dioxide-supported PdRu bimetallic catalyst for the selective catalytic reduction of _NOx with hydrogen. The composition of the catalyst is expressed as xPd-yRu/TiO ₂ , wherein the mass percentage of Pd is 0.2%≤x≤1%, the mass percentage of Ru is 0.05%≤y≤0.5%.

In a second aspect, the invention provides a method for preparing a TiO ₂ supported PdRu bimetallic catalyst, which method includes the following steps:

(1) Prepare 0.01~0.02mol/L palladium source solution and 0.001~0.01mol/L ruthenium source solution;

(2) Take the ruthenium source solution obtained in step (1), stir at 30-50°C, add titanium dioxide to the ruthenium source solution, stir, and prepare the first slurry;

(3) Dry the first slurry prepared in step (2) to prepare a dry sample;

(4) Take the palladium source solution obtained in step (1), stir at 30-50°C, add the dry sample powder obtained in step (3) to the palladium source solution, stir, and prepare a second slurry;

(5) Dry the second slurry obtained in step (4), and then calcine at 400-500°C to prepare the titanium dioxide-supported PdRu bimetallic catalyst.

Preferably, the palladium source in step (1) is selected from palladium nitrate and/or palladium chloride.

Preferably, the ruthenium source in step (1) is selected from ruthenium trichloride.

Preferably, the temperature control method in step (2) and step (4) is selected from water bath.

Preferably, the stirring time for forming the first slurry and the second slurry in step (2) and step (4) are each independently selected from 4 to 24 hours.

Preferably, the drying temperature in step (3) is selected from 100°C to 120°C, and the drying time is selected from 12 to 24 hours.

Preferably, the drying temperature in step (5) is selected from 100°C to 120°C, and the drying time is selected from 12 to 24 hours.

Preferably, the calcination time in step (5) is selected from 4 to 8 hours.

In a third aspect, the present invention provides the application of the titanium dioxide-supported PdRu bimetallic catalyst for the selective catalytic reduction of _NOx with hydrogen as described in the first aspect. The bimetallic catalyst is used for the selective catalytic reduction of nitrogen oxides with hydrogen.

Preferably, the bimetallic catalyst is used for the elimination of _NOx under low temperature conditions in the flue gas of hydrogen-fueled vehicles and industrial boilers.

Compared with the existing technology, the present invention has the following advantages and outstanding effects: on the TiO ₂ -supported PdRu bimetallic catalyst, through the synergistic effect between Pd and Ru, the content of Pd ⁰ on the PdRu/TiO ₂ catalyst is significantly higher than Pd/TiO ₂ catalyst, thereby broadening the activity temperature window of the catalyst and improving the denitrification performance of the catalyst. When the space velocity is 52000h ^-1 , the purification efficiency of _NOx reaches 55~87% in a wide temperature range of 125~300℃.

Specific implementation

The technical solution of the present invention will be further described below in conjunction with the examples:

Example 1: Preparation of 0.5%Pd-0.05%Ru/ _TiO2 catalyst

a) Take 4.95ml of 0.001mol/L ruthenium trichloride solution and stir in a 30°C water bath; add 1g of titanium dioxide to the solution and stir for 24 hours to prepare the first slurry;

b) Dry the first slurry prepared in step a) at 120°C for 12 hours to prepare a dry sample;

c) Take 4.71ml of 0.01mol/L palladium nitrate solution and stir in a 50°C water bath; add 1g of the dry sample powder obtained in step b) to the solution and stir for 12 hours to prepare a second slurry;

d) Dry the second slurry in step c) at 120°C for 12 hours, then place it in a muffle furnace and calcine at 400°C for 4 hours to prepare a 0.5% Pd-0.05% Ru/TiO ₂ catalyst .

Example 2: Preparation of 0.5%Pd-0.1%Ru/ _TiO2 catalyst

a) Take 4.95ml of 0.002mol/L ruthenium trichloride solution, stir in a 50°C water bath, add 1g of titanium dioxide to the solution, and stir for 4 hours to prepare the first slurry;

b) Dry the first slurry prepared in step a) at 120°C for 12 hours to prepare a dry sample;

c) Take 4.71ml of 0.01mol/L palladium nitrate solution, stir in a 30°C water bath, add 1g of the dry sample powder obtained in step b) to the solution, and stir for 24 hours to prepare a second slurry;

d) Dry the second slurry in step c) at 120°C for 24 hours, then place it in a muffle furnace and calcine at 500°C for 8 hours to prepare a 0.5% Pd-0.1% Ru/TiO ₂ catalyst .

Example 3: Preparation of 0.5%Pd-0.2%Ru/ _TiO2 catalyst

a) Take 4.95ml of 0.004mol/L ruthenium trichloride solution, stir in a 50°C water bath, add 1g of titanium dioxide to the solution, and stir for 12 hours to prepare the first slurry;

b) Dry the first slurry prepared in step a) at 120°C for 12 hours to prepare a dry sample;

c) Take 4.71ml of 0.01mol/L palladium chloride solution, stir in a 50°C water bath, add 1g of the dry sample powder obtained in step b) to the solution, stir for 4 hours, and prepare a second slurry;

d) Dry the second slurry in step c) at 120°C for 24 hours, then place it in a muffle furnace and calcine at 500°C for 4 hours to prepare a 0.5% Pd-0.2% Ru/TiO ₂ catalyst .

Example 4: Preparation of 0.5%Pd-0.5%Ru/ _TiO2 catalyst

a) Take 4.95ml of 0.01mol/L ruthenium trichloride solution, stir in a 50°C water bath, add 1g of titanium dioxide to the solution, and stir for 4 hours to prepare the first slurry;

b) Dry the first slurry prepared in step a) at 120°C for 12 hours to prepare a dry sample;

c) Take 4.71ml of 0.01mol/L palladium nitrate solution, stir in a 50°C water bath, add 1g of the dry sample powder obtained in step b) to the solution, stir for 4 hours, and prepare a second slurry;

d) Dry the second slurry in step c) at 120°C for 24 hours, then place it in a muffle furnace and calcine at 400°C for 8 hours to prepare a 0.5% Pd-0.5% Ru/TiO ₂ catalyst .

Example 5: Preparation of 0.2%Pd-0.5%Ru/ _TiO2 catalyst

a) Take 4.95ml of 0.01mol/L ruthenium trichloride solution, stir in a 30°C water bath, add 1g of titanium dioxide to the solution, and stir for 12 hours to prepare the first slurry;

b) Dry the first slurry prepared in step a) at 120°C for 24 hours to prepare a dry sample;

c) Take 1.88ml of 0.01mol/L palladium chloride solution, stir in a 50°C water bath, add 1g of the powder obtained in step b) to the solution, and stir for 4 hours to prepare a second slurry;

d) Dry the second slurry in step c) at 120°C for 24 hours, then place it in a muffle furnace and calcine at 500°C for 6 hours to prepare a 0.2% Pd-0.5% Ru/TiO ₂ catalyst .

Example 6: Preparation of 1%Pd-0.05%Ru/ _TiO2 catalyst

a) Take 4.95ml of 0.001mol/L ruthenium trichloride solution, stir in a 50°C water bath, add 1g of titanium dioxide to the solution, and stir for 12 hours to prepare the first slurry;

b) Dry the first slurry prepared in step a) at 120°C for 24 hours to prepare a dry sample;

c) Take 4.71ml of 0.02mol/L palladium nitrate solution, stir in a 40°C water bath, add 1g of the dry sample powder obtained in step b) to the solution, and stir for 12 hours to prepare a second slurry;

d) Dry the second slurry in step c) at 120°C for 24 hours, then place it in a muffle furnace and calcine at 500°C for 4 hours to prepare a 1% Pd-0.05% Ru/TiO ₂ catalyst .

Example 7 (Reference): Preparation of 0.5% Pd/TiO ₂ catalyst

a) Take 4.71ml of 0.01mol/L palladium nitrate solution, stir in a 40°C water bath, add 1g of titanium dioxide to the solution, and stir for 12 hours to prepare a slurry;

b) Dry the slurry in step a) at 120°C for 12 hours, then place it in a muffle furnace and calcine at 500°C for 6 hours to prepare a 0.5% Pd/TiO ₂ catalyst.

Example 8 (Reference): Preparation of 0.1% Ru/TiO ₂ catalyst

a) Take 4.95ml of 0.002mol/L ruthenium trichloride solution, stir in a 30°C water bath, add 1g of titanium dioxide to the solution, and stir for 24 hours to prepare a slurry;

b) Dry the slurry prepared in step a) at 120°C for 12 hours, then place it in a muffle furnace and calcine at 500°C for 4 hours to prepare a 0.1% Ru/TiO ₂ catalyst.

Example 9: The preparation method of the catalyst is the same as in Example 1. 0.2g of the catalyst is loaded into the fixed bed reactor. The reaction gas composition is 2000ppm NO, 1% H ₂ , 5% O ₂ , and the flow rate of the reaction gas is 200 mL/ min, the airspeed is 52,000h ^-1 . The activity evaluation temperature range is 125~300°C. The conversion rates of _NOx at different temperatures are shown in Table 1.

Example 10: The catalyst preparation method is the same as Example 2. 0.2g catalyst is loaded into the fixed bed reactor. The reaction gas composition is 2000ppm NO, 1% H ₂ , 5% O ₂ , and the flow rate of the reaction gas is 200 mL/ min, the airspeed is 52,000h ^-1 . The activity evaluation temperature range is 125~300°C. The conversion rates of _NOx at different temperatures are shown in Table 1.

Example 11: The preparation method of the catalyst is the same as in Example 3. 0.2g of the catalyst is loaded into the fixed bed reactor. The reaction gas composition is 2000ppm NO, 1% H ₂ , 5% O ₂ , and the flow rate of the reaction gas is 200 mL/ min, the airspeed is 52,000h ^-1 . The activity evaluation temperature range is 125~300°C. The conversion rates of _NOx at different temperatures are shown in Table 1.

Example 12: The preparation method of the catalyst is the same as in Example 4. 0.2g of the catalyst is loaded into the fixed bed reactor. The reaction gas composition is 2000ppm NO, 1% H ₂ , 5% O ₂ , and the flow rate of the reaction gas is 200 mL/ min, the airspeed is 52,000h ^-1 . The activity evaluation temperature range is 125~300°C. The conversion rates of _NOx at different temperatures are shown in Table 1.

Table 1 Activity evaluation results of titanium dioxide supported PdRu catalyst and reference catalyst

Example 13: The preparation method of the catalyst is the same as in Example 5. 0.2g of the catalyst is loaded into the fixed bed reactor. The reaction gas composition is 2000ppm NO, 1% H ₂ , 5% O ₂ , and the flow rate of the reaction gas is 200 mL/ min, the airspeed is 52,000h ^-1 . The activity evaluation temperature range is 125~300°C. The conversion rates of _NOx at different temperatures are shown in Table 1.

Example 14: The preparation method of the catalyst is the same as in Example 6. 0.2g of the catalyst is loaded into the fixed bed reactor. The reaction gas composition is 2000ppm NO, 1% H ₂ , 5% O ₂ , and the flow rate of the reaction gas is 200 mL/ min, the airspeed is 52,000h ^-1 . The activity evaluation temperature range is 125~300°C. The conversion rates of _NOx at different temperatures are shown in Table 1.

Claims (10)

1. A titanium dioxide-supported PdRu bimetallic catalyst for the selective catalytic reduction of _NOx with hydrogen, characterized in that the composition of the catalyst is expressed as xPd-yRu/TiO ₂ , wherein the mass percentage of Pd is 0.2% ≤x≤1%, the mass percentage of Ru is 0.05%≤y≤0.5%. 2. A method for preparing the titanium dioxide-loaded PdRu bimetallic catalyst as claimed in claim 1, characterized in that the method includes the following steps in sequence: (1) Prepare 0.01~0.02mol/L palladium source solution and 0.001~0.01mol/L ruthenium source solution; (2) Take the ruthenium source solution obtained in step (1), stir at 30°C to 50°C, add titanium dioxide to the ruthenium source solution, stir, and prepare the first slurry; (3) Dry the first slurry prepared in step (2) to prepare a dry sample; (4) Take the palladium source solution obtained in step (1), stir at 30-50°C, add the dry sample powder obtained in step (3) to the palladium source solution, stir, and prepare a second slurry; (5) Dry the second slurry obtained in step (4), and then calcine at 400-500°C to prepare the titanium dioxide-supported PdRu bimetallic catalyst. 3. The method of claim 2, wherein the palladium source in step (1) is selected from palladium nitrate and/or palladium chloride. 4. The method of claim 2, wherein the ruthenium source in step (1) is selected from ruthenium trichloride. 5. The method of claim 2, wherein the temperature control method in step (2) and step (4) is selected from water bath. 6. The method of claim 2, wherein the stirring times for forming the first slurry and the second slurry in steps (2) and (4) are each independently selected from 4 to 24 hours. 7. The method of claim 2, wherein in step (3), the drying temperature is selected from 100°C to 120°C, and the drying time is selected from 12 to 24 hours; In step (5), the drying temperature is selected from 100°C to 120°C, and the drying time is selected from 12 to 24 hours. 8. The method of claim 2, wherein the calcination time in step (5) is selected from 4 to 8 hours. 9. Application of the titanium dioxide-supported PdRu bimetallic catalyst for the selective catalytic reduction of _NOx with hydrogen according to claim 1, characterized in that the bimetallic catalyst is used for the selective catalytic reduction of nitrogen oxides with hydrogen. 10. The application according to claim 9, characterized in that the bimetallic catalyst is used for the elimination of _NOx under low temperature conditions in the flue gas of hydrogen fuel vehicles and industrial boilers.