SULPHUR TOLERANCE IN Cu-SCR CATALYSTS
The present invention relates to a catalyst composition. More particularly, the present invention relates to a catalyst composition comprising a low SAR zeolite, copper in an amount of at least 2 wt %; and a rare earth element. The present invention also relates to a method for the manufacture of a catalyst composition. The present invention further relates to a catalyst article comprising a catalyst composition and a method for the treatment of an exhaust gas which comprises contacting an exhaust gas with a catalyst article comprising a catalyst composition.
1 . A catalyst composition comprising:
a) a low SAR zeolite;
b) copper in an amount of at least 2 wt %; and
c) a rare earth element.
2 . The catalyst composition of claim 1 , wherein the zeolite has a SAR of between 10 and 25.
3 . The catalyst composition of claim 1 , wherein the zeolite has a SAR of between 11 to 21.
4 . The catalyst composition of claim 1 , wherein the copper is present in an amount of at least 2.5 wt %.
5 . The catalyst composition of claim 1 , wherein the copper is present in an amount of at least 3 wt %.
6 . The catalyst composition of claim 1 , wherein the copper is present in an amount of at least 4 wt %.
7 . The catalyst composition of claim 1 , wherein the rare earth element is selected from the group comprising La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc.
8 . The catalyst composition of claim 1 , wherein the rare earth element is present in an amount of from 2 to 5 wt %.
9 . The catalyst composition of claim 1 , wherein the rare earth element is present in an amount of from 2.75 to 4.5 wt %.
10 . The catalyst composition of claim 1 , wherein the zeolite is a small-pore zeolite.
11 . The catalyst composition of claim 10 , wherein the small-pore zeolite has a CHA or AEI framework structure type.
12 . A method of preparing a catalyst composition of claim 1 , the method comprising:
(i) incorporating copper into a zeolite to prepare a copper-substituted zeolite, and
(ii) incorporating a rare earth element into the copper-substituted zeolite.
13 . A catalyst article for an exhaust gas system, the catalyst article comprising a substrate and the catalyst composition of claim 1 .
14 . An exhaust gas system comprising the catalyst article of claim 13 and a combustion engine.
15 . A method for the treatment of an exhaust gas, the method comprising contacting an exhaust gas with the catalyst article according to claim 13 .