CATALYTIC PARTIAL WALL-FLOW FILTER
A catalytic partial wall-flow filter suitable for use in an exhaust gas treatment system, a method of making the catalytic partial wall-flow filter, and a method of using the catalytic partial wall-flow filter to remediate engine exhaust streams are disclosed. The filter comprises a partial wall-flow filter substrate having an inlet end, an outlet end, and a plurality of porous walls forming channels from the inlet end to the outlet end, wherein some of the channels are plugged channels and some are unplugged flow-through channels. A selective catalytic reduction (SCR) catalyst is coated on the porous walls.
1 . A catalytic partial wall-flow filter for use in an exhaust gas treatment system, the filter comprising:
a) a partial wall-flow filter substrate having an inlet end, an outlet end, and a plurality of porous walls forming channels from the inlet end to the outlet end, wherein some of the channels are plugged channels and some are unplugged flow-through channels; and
b) a selective catalytic reduction (SCR) catalyst coated on the porous walls.
2 . The catalytic partial wall-flow filter of claim 1 , wherein the channels are plugged only adjacent to the inlet end.
3 . The catalytic partial wall-flow filter of claim 2 , wherein about 50% of the channels are plugged.
4 . The catalytic partial wall-flow filter of claim 1 , wherein the channels are plugged only adjacent to the outlet end.
5 . The catalytic partial wall-flow filter of claim 4 , wherein about 50% of the channels are plugged.
6 . The catalytic partial wall-flow filter of claim 1 , wherein a hydraulic diameter of the plugged channels is larger than a hydraulic diameter of the unplugged flow-through channels.
7 . The catalytic partial wall-flow filter of claim 1 , wherein a hydraulic diameter of the plugged channels is smaller than a hydraulic diameter of the unplugged flow-through channels.
8 . The catalytic partial wall-flow filter of claim 1 , wherein the SCR catalyst comprises vanadium and antimony.
9 . The catalytic partial wall-flow filter of claim 8 , wherein the SCR catalyst has a molar ratio of antimony to vanadium of from 0.6 to 0.9.
10 . The catalytic partial wall-flow filter of claim 9 , wherein the SCR catalyst comprises vanadium, antimony, and cerium.
11 . The catalytic partial wall-flow filter of claim 1 , wherein the SCR catalyst has a coating length of from 50 to 90% of the substrate length (L).
12 . The catalytic partial wall-flow filter of claim 1 , wherein the SCR catalyst has a coating length of from 60 to 80% of the substrate length (L).
13 . A method for the manufacture of a catalytic partial wall-flow filter of claim 1 , the method comprising: (a) providing a partial wall-flow filter substrate having an inlet end, an outlet end, and a plurality of porous walls forming channels from the inlet end to the outlet end, wherein some of the channels are plugged channels and some are unplugged flow-through channels; (b) applying a SCR catalyst washcoat slurry on the porous walls to form a coated wall-flow filter substrate; and (c) calcining a coated wall-flow filter substrate obtained to produce the partial catalytic wall-flow filter.
14 . An exhaust gas treatment system for treating a flow of a combustion exhaust gas, the system comprising the catalytic partial wall-flow filter according to any of claim 1 .
15 . (canceled)