Exhaust gas purifying catalyst and process for purification of exhaust gas
View Patent ↗An exhaust gas purifying catalyst has a catalytic component including copper, ZSM-5, and β zeolite. This exhaust gas purifying catalyst reduces nitrogen oxides even from low temperature range and exhibits durability even under a thermal load of high temperature.
1. A catalyst for purifying exhaust gases, comprising a catalytic component including copper, ZSM-5, and β zeolite; wherein the ZSM-5 has a SiO 2 /Al 2 O 3 molar ratio of (20-100)/1 and an average crystal diameter observed under an electron microscope in a range not exceeding 0.5 μm, the β zeolite has a SiO 2 /Al 2 O 3 molar ratio of (10-50)/1, and the weight ratio of the ZSM-5 and the β zeolite is in the range of 1:0.1-1:5.
2. A catalyst according to claim 1 , wherein the copper is deposited on both of the ZSM-5 and the β zeolite.
3. A catalyst according to claim 1 , wherein, on a refractory three-dimensional structure, the zeolite is deposited in the range of 70-300 g and the copper is deposited in the state of oxide in the range of 3-30 g per liter of the refractory three-dimensional structure.
4. A catalyst according to claim 1 further comprising at least one element selected from the group consisting of phosphorus, cerium, and boron.
5. A process for purifying an exhaust gas, which comprises treating an exhaust gas from a diesel engine with a catalyst set forth in claim 1 .
6. A catalyst according to claim 1 , wherein the copper is deposited on both of the ZSM-5 and the β zeolite.
7. A catalyst according to claim 1 , wherein the copper is deposited on both of the ZSM-5 and the β zeolite.
8. A catalyst according to claim 1 , wherein, on a refractory three-dimensional structure, the zeolite is deposited in the range of 70-300 g and the copper is deposited in the state of oxide in the range of 3-30 g per liter of the refractory three-dimensional structure.
9. A catalyst according to claim 1 , wherein, on a refractory three-dimensional structure, the zeolite is deposited in the range of 70-300 g and the copper is deposited in the state of oxide in the range of 3-30 g per liter of the refractory three-dimensional structure.
10. A catalyst according to claim 2 , wherein, on a refractory three-dimensional structure, the zeolite is deposited in the range of 70-300 g and the copper is deposited in the state of oxide in the range of 3-30 g per liter of the refractory three-dimensional structure.
11. A catalyst according to claim 1 further comprising at least one element selected from the group consisting of phosphorus, cerium, and boron.
12. A catalyst according to claim 1 further comprising at least one element selected from the group consisting of phosphorus, cerium, and boron.
13. A catalyst according to claim 2 further comprising at least one element selected from the group consisting of phosphorus, cerium, and boron.
14. A catalyst according to claim 3 further comprising at least one element selected from the group consisting of phosphorus, cerium, and boron.
15. A process for purifying an exhaust gas, which comprises treating an exhaust gas from a diesel engine with a catalyst set forth in claim 1 .
16. A process for purifying an exhaust gas, which comprises treating an exhaust gas from a diesel engine with a catalyst set forth in claim 1 .
17. A process for purifying an exhaust gas, which comprises treating an exhaust gas from a diesel engine with a catalyst set forth in claim 2 .
18. A process for purifying an exhaust gas, which comprises treating an exhaust gas from a diesel engine with a catalyst set forth in claim 3 .
19. A process for purifying an exhaust gas, which comprises treating an exhaust gas from a diesel engine with a catalyst set forth in claim 4 .