Exhaust gas purification system for a gasoline engine
Subject of the invention is an exhaust gas purification system for a gasoline engine, comprising in consecutive order the following devices: a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2), wherein the wash coat load (WCL) of the GPF is greater than the WCL of the TWC2, wherein the WCL is determined in g/l of the volume of the device. The invention also relates to methods in which the system is used and uses of the system.
1. An exhaust gas purification system for a gasoline engine, comprising in consecutive order the following devices:
a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2),
wherein the wash coat load (WCL) of the GPF is greater than the WCL of the TWC2, wherein the WCL is determined in g/l of the volume of the device,
wherein the platinum-group metal concentration (PGM) of the TWC1 is at least 40% greater than the PGM of the TWC2, wherein the PGM is determined in g/ft 3 of the volume of the device.
2. The system according to claim 1 , wherein the platinum-group metal concentration (PGM) of the GPF is at least 40% greater than the PGM of the TWC2, wherein the PGM is determined in g/ft 3 of the volume of the device.
3. The system according to claim 1 , wherein the ratio of the platinum-group metal concentration (PGM) of the TWC1 to the PGM of the GPF is from 1.1 to 10, wherein the PGM is determined in g/ft 3 of the volume of the device, and/or
wherein the platinum-group metal concentration (PGM) of the TWC1 is at least 40% greater than the PGM of the GPF, wherein the PGM is determined in g/ft 3 of the volume of the device.
4. The system according to claim 3 , wherein the ratio of the platinum-group metal concentration (PGM) of the TWC1 to the PGM of the GPF is from 1.45 to 5.
5. The system according to claim 1 , wherein the total amount of platinum-group metal of the TWC2 is from 0.1 g to 2 g, and/or
wherein the percentage of rhodium of the total amount of platinum-group metal of the TWC2 is at least 15 wt. %.
6. The system according to claim 1 , wherein the GPF comprises palladium, platinum, rhodium or mixtures thereof.
7. The system according to claim 6 , wherein the percentage of rhodium of the total amount of platinum-group metal of the GPF is at least 10 wt. %.
8. The system according to claim 1 , wherein the platinum-group metal concentration (PGM) of the TWC2 is greater than the PGM of the GPF, wherein the PGM is determined in g/ft 3 of the volume of the device.
9. The system according to claim 1 , wherein the ratio of the platinum-group metal concentration (PGM) of the TWC1 to the PGM of the TWC2 is from 1.1 to 10, wherein the PGM is determined in g/ft 3 of the volume of the device.
10. The system according to claim 9 , wherein the ratio of the platinum-group metal concentration (PGM) of the TWC1 to the PGM of the TWC2 is from 1.45 to 5.
11. The system according to claim 1 , wherein the total amount of platinum-group metal of the TWC2 is from 0.1 g to 8 g, and/or
wherein the TWC2 comprises palladium and/or rhodium.
12. The system according to claim 1 , wherein the percentage of rhodium of the total amount of platinum-group metal of the TWC2 is at least 10 wt. %.
13. The system according to claim 1 , wherein the wash coat load (WCL) of the GPF is from 100 g/l to 200 g/l.
14. The system according to claim 13 , wherein the wash coat load (WCL) of the GPF is from 130 g/l to 160 g/l.
15. The system according to claim 1 , wherein the wash coat load (WCL) of the TWC2 is from 80 g/l to 160 g/l.
16. The system according to claim 1 , wherein the oxygen storage capacity (OSC) of the GPF is greater than the OSC of the TWC2, wherein the OSC is determined in mg/l of the volume of the device.
17. The system according to claim 1 , wherein the oxygen storage capacity (OSC) of the TWC1 is greater than the OSC of the GPF, wherein the OSC is determined in mg/l of the volume of the device.
18. The system according to claim 1 , wherein the oxygen storage capacity (OSC) of the TWC1 is from 400 mg to 1250 mg.
19. An exhaust gas purification system for a gasoline engine, comprising in consecutive order the following devices:
a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2),
wherein the wash coat load (WCL) of the GPF is greater than the WCL of the TWC2, wherein the WCL is determined in g/l of the volume of the device,
wherein the oxygen storage capacity (OSC) of the TWC1 is from 400 mg to 1250 mg.
20. The system according to claim 19 , wherein the oxygen storage capacity (OSC) of the TWC1 is from 500 mg to 900 mg.
21. An exhaust gas purification system for a gasoline engine, comprising in consecutive order the following devices:
a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2),
wherein the wash coat load (WCL) of the GPF is greater than the WCL of the TWC2, wherein the WCL is determined in g/l of the volume of the device,
wherein the platinum-group metal concentration (PGM) of the TWC1 is at least 40% greater than the PGM of the TWC2, wherein the PGM is determined in g/ft 3 of the volume of the device,
wherein the ratio of the platinum-group metal concentration (PGM) of the TWC1 to the PGM of the GPF is from 1.1 to 10, wherein the PGM is determined in g/ft 3 of the volume of the device, and/or
wherein the platinum-group metal concentration (PGM) of the TWC1 is at least 40% greater than the PGM of the GPF, wherein the PGM is determined in g/ft 3 of the volume of the device.