Tetra-functional catalyst for the oxidation of NO, the oxidation of a hydrocarbon, the oxidation of NH3 and the selective catalytic reduction of NO
The present invention relates to a catalyst, preferably for the selective catalytic reduction of NOx, for the oxidation of ammonia, for the oxidation of NO and for the oxidation of a hydrocarbon, the catalyst comprising a washcoat comprising one or more layers, the washcoat being disposed on a substrate, wherein the washcoat comprises a platinum group metal supported on a metal oxide support material, and one or more of an oxidic compound of V, an oxidic compound of W and a zeolitic material comprising one or more of Cu and Fe.
1. An exhaust gas treatment system in fluid communication with a heavy-duty diesel engine comprising
a first reductant injector,
a first catalyst for selective catalytic reduction of NO x ,
a second catalyst, wherein the second catalyst is a catalyst comprising a washcoat comprising a first layer and a second layer, the washcoat being disposed on a substrate, wherein the washcoat comprises
(i) a second layer comprising a platinum group metal supported on a metal oxide support material, and
(ii) a first layer comprising at least one chosen from an oxidic compound V, an oxidic compound of W, and a zeolitic material comprising one or more of Cu and Fe; wherein the first layer does not comprise any platinum group metal;
a catalyzed soot filter,
a second reductant injector,
a third catalyst for selective catalytic reduction of NO x , and
a fourth ammonia catalyst for selective catalytic reduction of NO x and/or for the oxidation of ammonia;
wherein the exhaust gas treatment system contains no diesel oxidation catalyst; wherein the first catalyst is located upstream of the second catalyst, the second catalyst is located upstream of the third catalyst, and the third catalyst is located upstream of the fourth catalyst.
2. The exhaust gas treatment system of claim 1 , wherein the catalyst is located up stream of the catalyzed soot filter, and wherein no diesel oxidation catalyst is located between the catalyst and the catalyzed soot filter.
3. The exhaust gas treatment system of claim 1 , wherein the platinum group metal is at least one chosen from Pt, Pd and Rh.
4. The exhaust gas treatment system of claim 1 , wherein the framework structure of the zeolitic material comprises a tetravalent element Y which is at least one chosen from Si, Sn, Ti, Zr, and Ge.
5. The exhaust gas treatment system of claim 1 , wherein the zeolitic material has a framework structure of the type AEI, GME, BEA, CHA, FAU, FER, HEU, LEV, MEI, MEL, MFI, or MOR.
6. The exhaust gas treatment system of claim 1 , wherein the substrate has a plurality of longitudinally extending passages formed by longitudinally extending walls bounding and defining the passages and a longitudinal total length extending between a front end and a rear end of the substrate.
7. The exhaust gas treatment system of claim 1 , wherein the substrate has a substrate length, and wherein the one layer is disposed on 50% to 100%, of the total length of the substrate.
8. The exhaust gas treatment system of claim 1 , wherein the first layer is disposed on the substrate and the second layer is at least partially disposed on the first layer, or wherein the second layer is disposed on the substrate and the first layer is at least partially disposed on the second layer.
9. The exhaust gas treatment system of claim 8 , wherein the washcoat further comprises a third layer, wherein the third layer comprises one or more of an oxidic compound of V, an oxidic compound of W, and a zeolitic material comprising one or more of Cu and Fe.
10. The exhaust gas treatment system of claim 1 , wherein the catalyst is located upstream of a catalyzed soot filter.
11. The exhaust gas treatment system of claim 1 , wherein the first reductant injector is a urea injector.
12. The exhaust gas treatment system of claim 1 , wherein the catalyst is downstream of the internal combustion engine.