A catalyst that promotes the purification of automobile exhaust.

Abstract

This invention provides a catalyst for promoting the purification of automobile exhaust gases. The catalyst includes a support and a coating applied to the support. The coating includes a lower coating layer disposed on the support and an upper coating layer disposed on the lower coating layer. The lower coating layer includes an intake section and an exhaust section. The intake section includes a noble metal Rh supported on a CeAl solid solution, and the exhaust section includes a noble metal Pd supported on a La2O3-Al2O3 solid solution. The upper coating layer includes Mn supported on a titanium dioxide and cerium-zirconium solid solution. This invention's catalyst for promoting the purification of automobile exhaust gases enhances exhaust gas purification performance by optimizing the coating composition and noble metal distribution. The lower coating layer, with Rh supported on a CeAl solid solution, prevents excessive aging of Rh, which could lead to a decrease in Rh reduction performance. The Pd supported on the later La2O3-Al2O3 solid solution improves the Pd's resistance to degradation. The upper coating layer, with Mn supported on TiO2 and a cerium-zirconium solid solution, promotes the conversion of NOx under different operating conditions.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more particularly to a catalyst that promotes the purification of automobile exhaust. Background Technology

[0002] A three-way catalytic converter for gasoline vehicles refers to a catalyst that converts carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) in vehicle exhaust into harmless carbon dioxide (CO2), water (H2O), and nitrogen (N2) through a catalytic reaction. With societal development and the continuous increase in the number of motor vehicles globally, vehicle exhaust pollutants have become one of the main sources of urban air pollution, not only harming human health but also causing significant damage to the ecological environment. Therefore, countries are formulating increasingly stringent vehicle emission regulations to limit the emission of gaseous pollutants. With the implementation of the "China VI" emission standard, higher requirements have been placed on the performance of three-way catalytic converters.

[0003] Improving the performance of automotive exhaust purification catalysts is of great significance for the upgrading of my country's automotive industry and the prevention and control of air pollution. Summary of the Invention

[0004] The purpose of this invention is to overcome and supplement the deficiencies in the existing technology, and to provide a catalyst that promotes the purification of automobile exhaust gas by optimizing the coating composition and the distribution of precious metals to enhance the exhaust gas purification performance.

[0005] The technical solution adopted in this invention is:

[0006] A catalyst for promoting the purification of automobile exhaust, wherein: the catalyst includes a carrier and a coating applied to the carrier, the coating includes a lower coating disposed on the carrier and an upper coating disposed on the lower coating, the lower coating includes an intake section and an exhaust section, the intake section includes a noble metal Rh supported on a CeAl solid solution, the exhaust section includes a noble metal Pd supported on a La2O3-Al2O3 solid solution; the upper coating includes Mn supported on a titanium dioxide and cerium-zirconium solid solution.

[0007] Preferably, the catalyst for promoting the purification of automobile exhaust gas includes the following components in the CeAl solid solution: 20wt% to 80wt% CeO2 and 80wt% to 20wt% Al2O3.

[0008] Preferably, the catalyst for promoting the purification of automobile exhaust gas comprises the following components: 1 wt% to 10 wt% of La2O3 and 90 wt% to 99 wt% of Al2O3.

[0009] Preferably, the catalyst for promoting the purification of automobile exhaust gas includes a cerium-zirconium solid solution comprising ZrO2 and CeO2, wherein the content of CeO2 is 50wt% to 95wt%.

[0010] Preferably, in the catalyst for promoting the purification of automobile exhaust, the cerium-zirconium solid solution further comprises La2O3, Y2O3, and Pr6O. 11 It contains one or more of Nd2O3, with a content of 1wt% to 10wt%.

[0011] Preferably, in the catalyst for promoting the purification of automobile exhaust, the source of Mn is one or more of manganese acetate, manganese nitrate, and manganese chloride.

[0012] Preferably, in the catalyst for promoting the purification of automobile exhaust, the coating amount of the intake section is 50-300 g / L, and the coating amount of the outlet section is 50-150 g / L.

[0013] Preferably, in the catalyst for promoting the purification of automobile exhaust, the coating amount of the upper coating is 50-130 g / L.

[0014] Preferably, in the catalyst for promoting the purification of automobile exhaust, the content of Rh in the intake section is 0.1-10 g / ft3, the content of Pd in ​​the outlet section is 1-150 g / ft3, and the content of Mn in the upper coating is 0.05-10 g / ft3.

[0015] Preferably, in the catalyst for promoting the purification of automobile exhaust, the mass ratio of titanium dioxide to cerium-zirconium solid solution is 1:10 to 10:1.

[0016] Advantages of this invention:

[0017] (1) The catalyst for promoting the purification of automobile exhaust gas of the present invention enhances the exhaust gas purification performance by optimizing the coating composition and the distribution of precious metals. The lower coating Rh is loaded on CeAl solid solution to avoid Rh being over-aged and causing a decrease in Rh reduction performance. Pd is loaded on the later La2O3-Al2O3 to improve the anti-deterioration performance of Pd. The upper coating Mn is loaded on TiO2 and cerium-zirconium solid solution to promote the conversion of NOx under different working conditions.

[0018] (2) The catalyst for promoting the purification of automobile exhaust gas of the present invention includes a carrier and a coating applied to the carrier. The coating includes a lower coating disposed on the carrier and an upper coating disposed on the lower coating. The lower coating includes an intake section and an exhaust section. The intake section includes a noble metal Rh, which is supported on a CeAl solid solution. The exhaust section includes a noble metal Pd, which is supported on a La2O3-Al2O3. The upper coating includes Mn, which is supported on a titanium dioxide and cerium-zirconium solid solution. The above components enhance the exhaust gas purification performance of the catalyst through synergistic effect. Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments.

[0020] Example 1

[0021] A catalyst for promoting the purification of automobile exhaust includes a carrier and a coating applied to the carrier. The coating includes a lower coating disposed on the carrier and an upper coating disposed on the lower coating. The lower coating includes an intake section and an exhaust section. The intake section includes a noble metal Rh supported on a CeAl solid solution. The exhaust section includes a noble metal Pd supported on a La2O3-Al2O3 solid solution. The upper coating includes Mn supported on a titanium dioxide and cerium-zirconium solid solution.

[0022] The CeAl solid solution comprises 20 wt% CeO2 and 80 wt% Al2O3, the La2O3-Al2O3 comprises 2 wt% La2O3 and 98 wt% Al2O3, and the cerium-zirconium solid solution comprises ZrO2, CeO2 and Y2O3, wherein the content of CeO2 is 50 wt%, the content of ZrO2 is 45 wt%, and the content of Y2O3 is 5 wt%.

[0023] The preparation method of the above-mentioned catalyst for promoting automobile exhaust purification includes the following steps:

[0024] (1) Coating of the lower inlet section: 500g CeAl solid solution was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 10g rhodium nitrate solution (containing 10wt% Rh) was added dropwise to prepare the lower inlet section slurry. A coating amount of 100g / L was applied to one-quarter of the catalyst length from the inlet section. The slurry was then dried quickly at 100℃ for 8min.

[0025] (2) Coating of the lower gas outlet section: 500g La2O3-Al2O3 was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 10g palladium nitrate solution (containing 10wt% Pd) was added dropwise to prepare the lower gas inlet slurry. The slurry was coated from the gas outlet section to three-quarters of the catalyst length with a coating amount of 100g / L. The catalyst was dried quickly at a temperature of 180℃ for 8min. The dried catalyst was then heated to 500℃ at a heating rate of 10℃ / min and calcined for 1h to obtain the catalyst semi-finished product.

[0026] (3) Coating of the upper coating: 250g of titanium dioxide and 250g of cerium zirconium solid solution were added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 25g of manganese nitrate solution (containing 10wt% Mn) was added dropwise to prepare the upper coating slurry. The slurry was coated from the air inlet section to the catalyst semi-finished product obtained in step (2) at a coating amount of 80g / L. The drying temperature was 180℃ and the drying time was 8min. After drying, the temperature was increased to 500℃ at a heating rate of 20℃ / min and calcined for 2h to obtain the catalyst finished product.

[0027] Example 2

[0028] A catalyst for promoting the purification of automobile exhaust includes a carrier and a coating applied to the carrier. The coating includes a lower coating disposed on the carrier and an upper coating disposed on the lower coating. The lower coating includes an intake section and an exhaust section. The intake section includes a noble metal Rh supported on a CeAl solid solution. The exhaust section includes a noble metal Pd supported on a La2O3-Al2O3 solid solution. The upper coating includes Mn supported on a titanium dioxide and cerium-zirconium solid solution.

[0029] The CeAl solid solution comprises 50 wt% CeO2 and 50 wt% Al2O3, the La2O3-Al2O3 comprises 4 wt% La2O3 and 96 wt% Al2O3, and the cerium-zirconium solid solution comprises ZrO2, CeO2 and Nd2O3, wherein the content of CeO2 is 60 wt%, the content of ZrO2 is 35 wt%, and the content of Nd2O3 is 5 wt%.

[0030] The preparation method of the above-mentioned catalyst for promoting automobile exhaust purification includes the following steps:

[0031] (1) Coating of the lower inlet section: 500g CeAl solid solution was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 5g rhodium nitrate solution (containing 10wt% Rh) was added dropwise to prepare the lower inlet section slurry. Half of the catalyst length was coated from the inlet section with a coating amount of 100g / L. The slurry was dried quickly at 100℃ for 8min.

[0032] (2) Coating of the lower gas outlet section: 500g La2O3-Al2O3 was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 10g palladium nitrate solution (containing 10wt% Pd) was added dropwise to prepare the lower gas inlet slurry. Half of the catalyst length was coated from the gas outlet section with a coating amount of 100g / L. The catalyst was dried quickly at 180℃ for 8min. Then the dried catalyst was heated to 500℃ at a heating rate of 10℃ / min and calcined for 1h to obtain the catalyst semi-finished product.

[0033] (3) Coating of the upper coating: 100g of titanium dioxide and 400g of cerium zirconium solid solution were added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 25g of manganese chloride solution (containing 10wt% Mn) was added dropwise to prepare the upper coating slurry. The slurry was coated from the air inlet section to the catalyst semi-finished product obtained in step (2) at a coating amount of 80g / L. The drying temperature was 180℃ and the drying time was 8min. After drying, the temperature was increased to 500℃ at a heating rate of 20℃ / min and calcined for 2h to obtain the catalyst finished product.

[0034] Example 3

[0035] A catalyst for promoting the purification of automobile exhaust includes a carrier and a coating applied to the carrier. The coating includes a lower coating disposed on the carrier and an upper coating disposed on the lower coating. The lower coating includes an intake section and an exhaust section. The intake section includes a noble metal Rh supported on a CeAl solid solution. The exhaust section includes a noble metal Pd supported on a La2O3-Al2O3 solid solution. The upper coating includes Mn supported on a titanium dioxide and cerium-zirconium solid solution.

[0036] The CeAl solid solution comprises 80 wt% CeO2 and 20 wt% Al2O3, the La2O3-Al2O3 comprises 4 wt% La2O3 and 96 wt% Al2O3, and the cerium-zirconium solid solution comprises ZrO2, CeO2 and La2O3, wherein the content of CeO2 is 70 wt%, the content of ZrO2 is 25 wt%, and the content of La2O3 is 5 wt%.

[0037] The preparation method of the above-mentioned catalyst for promoting automobile exhaust purification includes the following steps:

[0038] (1) Coating of the lower inlet section: 500g CeAl solid solution was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 10g rhodium nitrate solution (containing 10wt% Rh) was added dropwise to prepare the lower inlet section slurry. A coating amount of 100g / L was applied to one-quarter of the catalyst length from the inlet section. The slurry was then dried quickly at 100℃ for 8min.

[0039] (2) Coating of the lower gas outlet section: 500g La2O3-Al2O3 was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 15g palladium nitrate solution (containing 10wt% Pd) was added dropwise to prepare the lower gas inlet slurry. The slurry was coated from the gas outlet section to three-quarters of the catalyst length with a coating amount of 100g / L. The catalyst was dried quickly at a temperature of 180℃ for 8min. The dried catalyst was then heated to 500℃ at a heating rate of 10℃ / min and calcined for 1h to obtain the catalyst semi-finished product.

[0040] (3) Coating of the upper coating: 400g of titanium dioxide and 100g of cerium zirconium solid solution were added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 25g of manganese acetate solution (containing 10wt% Mn) was added dropwise to prepare the upper coating slurry. The slurry was coated from the air inlet section to the catalyst semi-finished product obtained in step (2) at a coating amount of 80g / L. The drying temperature was 180℃ and the drying time was 8min. After drying, the temperature was increased to 500℃ at a heating rate of 20℃ / min and calcined for 2h to obtain the catalyst finished product.

[0041] Comparative Example 1

[0042] A catalyst for promoting the purification of automobile exhaust includes a carrier and a coating applied to the carrier. The coating includes a lower coating disposed on the carrier and an upper coating disposed on the lower coating. The lower coating includes an inlet section and an outlet section. The inlet section includes a noble metal Rh supported on a CeAl solid solution. The outlet section includes a noble metal Pd supported on a La2O3-Al2O3 solid solution. The upper coating includes Mn supported on a cerium-zirconium solid solution.

[0043] The CeAl solid solution comprises 20 wt% CeO2 and 80 wt% Al2O3, the La2O3-Al2O3 comprises 2 wt% La2O3 and 98 wt% Al2O3, and the cerium-zirconium solid solution comprises ZrO2, CeO2 and Y2O3, wherein the content of CeO2 is 50 wt%, the content of ZrO2 is 45 wt%, and the content of Y2O3 is 5 wt%.

[0044] The preparation method of the above-mentioned catalyst for promoting automobile exhaust purification includes the following steps:

[0045] (1) Coating of the lower inlet section: 500g CeAl solid solution was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 10g rhodium nitrate solution (containing 10wt% Rh) was added dropwise to prepare the lower inlet section slurry. A coating amount of 100g / L was applied to one-quarter of the catalyst length from the inlet section. The slurry was then dried quickly at 100℃ for 8min.

[0046] (2) Coating of the lower gas outlet section: 500g La2O3-Al2O3 was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 10g palladium nitrate solution (containing 10wt% Pd) was added dropwise to prepare the lower gas inlet slurry. The slurry was coated from the gas outlet section to three-quarters of the catalyst length with a coating amount of 100g / L. The catalyst was dried quickly at a temperature of 180℃ for 8min. The dried catalyst was then heated to 500℃ at a heating rate of 10℃ / min and calcined for 1h to obtain the catalyst semi-finished product.

[0047] (3) Coating of the upper coating: 500g of cerium-zirconium solid solution was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 25g of manganese nitrate solution (containing 10wt% Mn) was added dropwise to prepare the upper coating slurry. The slurry was coated from the air inlet section to the catalyst semi-finished product obtained in step (2) at a coating amount of 80g / L. The drying temperature was 180℃ and the drying time was 8min. After drying, the temperature was increased to 500℃ at a heating rate of 20℃ / min and calcined for 2h to obtain the catalyst finished product.

[0048] Comparative Example 2

[0049] A catalyst for promoting the purification of automobile exhaust includes a carrier and a coating applied to the carrier. The coating includes a lower coating disposed on the carrier and an upper coating disposed on the lower coating. The lower coating includes an intake section and an exhaust section. The intake section includes a noble metal Rh supported on a CeAl solid solution. The exhaust section includes a noble metal Pd supported on a La2O3-Al2O3 solid solution. The upper coating includes Mn supported on a titanium dioxide and cerium-zirconium solid solution.

[0050] The La2O3-Al2O3 comprises the following components: 4 wt% La2O3 and 96 wt% Al2O3. The cerium-zirconium solid solution comprises ZrO2, CeO2, and Nd2O3, wherein the content of CeO2 is 60 wt%, the content of ZrO2 is 35 wt%, and the content of Nd2O3 is 5 wt%.

[0051] The preparation method of the above-mentioned catalyst for promoting automobile exhaust purification includes the following steps:

[0052] (1) Coating of the lower inlet section: 500g of cerium zirconium solid solution was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 5g of rhodium nitrate solution (containing 10wt% Rh) was added dropwise to prepare the lower inlet section slurry. Half of the catalyst length was coated from the inlet section with a coating amount of 100g / L. The slurry was dried quickly at 100℃ for 8min.

[0053] (2) Coating of the lower gas outlet section: 500g La2O3-Al2O3 was added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 10g palladium nitrate solution (containing 10wt% Pd) was added dropwise to obtain the lower gas inlet slurry. Half of the catalyst length was coated from the gas outlet section with a coating amount of 100g / L. The catalyst was dried quickly at a temperature of 180℃ for 8min. Then the dried catalyst was heated to 500℃ at a heating rate of 10℃ / min and calcined for 1h to obtain the catalyst semi-finished product.

[0054] (3) Coating of the upper coating: 100g of titanium dioxide and 400g of cerium zirconium solid solution were added to deionized water and stirred for 30min. The particle size was controlled to be 15μm by ball milling. 25g of manganese chloride solution (containing 10wt% Mn) was added dropwise to prepare the upper coating slurry. The slurry was coated from the air inlet section to the catalyst semi-finished product obtained in step (2) at a coating amount of 80g / L. The drying temperature was 180℃ and the drying time was 8min. After drying, the temperature was increased to 500℃ at a heating rate of 20℃ / min and calcined for 2h to obtain the catalyst finished product.

[0055] The catalysts prepared in Examples 1-3 and Comparative Examples 1-2 were tested using the following methods:

[0056] The catalyst samples obtained in Examples 1-3 and Comparative Examples 1-2 were aged for 20 hours in a high-temperature tubular furnace at 1050°C under the same conditions and in an atmosphere of N2. They were then packaged as purifiers and subjected to vehicle emission tests according to the WLTC I type test. Examples 1-3 and Comparative Examples 1-2 were tested under the same conditions. The engine displacement of the test vehicle was 1.6L. The emission test results are shown in Table 1.

[0057] Table 1. Comparison of catalytic performance of catalysts obtained in Examples 1-3 and Comparative Examples 1-2

[0058] THC (mg / km) CO (mg / km) <![CDATA[NO X (mg / km)]]> Example 1 19.5 162.1 30.3 Example 2 21.5 210.7 31.2 Example 3 22.7 220.4 33.8 Comparative Example 1 38.3 296.7 41.6 Comparative Example 2 41.5 310.6 44.9

[0059] Note: In Table 1, THC is an abbreviation for the total amount of hydrocarbons contained in the gas.

[0060] As shown in Table 1, the results of the catalyst performance evaluation show that, compared with Comparative Examples 1-2, the three-way catalysts prepared in Examples 1-3 of the present invention have excellent exhaust gas purification capabilities under various transient operating conditions, and exhibit good catalytic performance in the conversion of CO, HC and NOx.

[0061] The catalyst for promoting automobile exhaust purification of the present invention includes a carrier and a coating applied to the carrier. The coating includes a lower coating disposed on the carrier and an upper coating disposed on the lower coating. The lower coating includes an intake section and an exhaust section. The intake section includes a noble metal Rh supported on a CeAl solid solution, and the exhaust section includes a noble metal Pd supported on a La2O3-Al2O3 solid solution. The upper coating includes Mn supported on a titanium dioxide and cerium-zirconium solid solution. The present invention enhances exhaust purification performance by optimizing the coating composition and the distribution of noble metals.

[0062] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A catalyst for promoting the purification of automobile exhaust, characterized in that: The catalyst includes a support and a coating applied to the support. The coating includes a lower coating disposed on the support and an upper coating disposed on the lower coating. The lower coating includes an inlet section and an outlet section. The inlet section includes a noble metal Rh supported on a CeAl solid solution. The outlet section includes a noble metal Pd supported on a La2O3-Al2O3 solid solution. The upper coating includes Mn supported on a titanium dioxide and cerium-zirconium solid solution. CeAl solid solution comprises the following components: 20 wt% to 80 wt% CeO2 and 80 wt% to 20 wt% Al2O3; The mass ratio of titanium dioxide to cerium-zirconium solid solution is 1:10 to 10:

1.

2. The catalyst for promoting the purification of automobile exhaust according to claim 1, characterized in that: La2O3-Al2O3 comprises the following components: 1 wt% to 10 wt% of La2O3 and 90 wt% to 99 wt% of Al2O3.

3. The catalyst for promoting the purification of automobile exhaust according to claim 1, characterized in that: The cerium-zirconium solid solution includes ZrO2 and CeO2, with the CeO2 content ranging from 50 wt% to 95 wt%.

4. The catalyst for promoting the purification of automobile exhaust according to claim 1, characterized in that: The cerium-zirconium solid solution also includes La2O3, Y2O3, and Pr6O. 11 It contains one or more of Nd2O3, with a content of 1 wt% to 10 wt%.

5. The catalyst for promoting the purification of automobile exhaust according to claim 1, characterized in that: The source of Mn is one or more of manganese acetate, manganese nitrate, and manganese chloride.

6. The catalyst for promoting the purification of automobile exhaust according to claim 1, characterized in that: The coating amount of the air intake section is 50-300 g / L, and the coating amount of the air outlet section is 50-150 g / L.

7. The catalyst for promoting the purification of automobile exhaust according to claim 1, characterized in that: The coating amount of the upper coating is 50~130g / L.

8. The catalyst for promoting the purification of automobile exhaust according to claim 1, characterized in that: The Rh content in the intake section is 0.1~10 g / ft. 3 The Pd content in the outlet section is 1~150 g / ft. 3 The Mn content of the upper coating is 0.05~10 g / ft. 3 .