PGM catalyst coupled with a non-PGM catalyst with HC oxidation capability

1. A diesel oxidation catalyst comprising a substrate and a washcoat comprising a first layer and a second layer, wherein the substrate has a substrate length, a front end and a rear end,

the first layer comprising a first metal oxide and a platinum group metal supported on titania, wherein the platinum group metal is not supported on the first metal oxide;

the second layer comprising a second metal oxide, and an oxidic compound of vanadium;

wherein the first layer is at least partially disposed directly on the substrate or is at least partially disposed directly on an intermediate layer which is disposed directly on the substrate over the entire length of the substrate,

wherein the first layer is disposed, directly or indirectly, on x % of the length of the substrate from the front end of the substrate,

wherein the second layer is at least partially disposed directly on the substrate or is at least partially disposed directly on the intermediate layer which is disposed directly on the substrate over the entire length of the substrate,

wherein the second layer is disposed, directly or indirectly, on y % of the length of the substrate from the rear end of the substrate,

wherein x is in the range of from 25 to 75 and y is in the range of from 25 to 75 and wherein x+y is in the range of from 95 to 105, and

wherein the intermediate layer comprises alumina.

2. The diesel oxidation catalyst of claim 1 , wherein x ranges from 30 to 70.

3. The diesel oxidation catalyst of claim 1 , wherein y ranges from 30 to 70.

4. The diesel oxidation catalyst of claim 1 , wherein x+y ranges from 96 to 104.

5. The diesel oxidation catalyst 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 the front end and the rear end of the substrate.

6. The diesel oxidation catalyst of claim 1 , wherein the first metal oxide is one or more of gamma-alumina, zirconia-alumina, silica-alumina, silica, lanthana, lanthana-alumina, alumina-zirconia-lanthana, titania, zirconia-titania, ceria, ceria-zirconia, or ceria-alumina.

7. The diesel oxidation catalyst of claim 1 wherein the platinum group metal is one or more of Pt, Pd, or Rh.

8. The diesel oxidation catalyst of claim 1 , wherein the second metal oxide is one or more of gamma-alumina, zirconia-alumina, silica-alumina, silica, lanthana, lanthana-alumina, alumina-zirconia-lanthana, titania, titania-silica, zirconia-titania, ceria, ceria-zirconia, ceria-alumina, or ferrous oxide.

9. The diesel oxidation catalyst of claim 1 , wherein the oxidic compound of vanadium is one or more of an ammonium vanadate, a sodium vanadate, an iron vanadate, vanadium pentoxide, or vanadium pentoxide stabilized with ferric oxide.

10. A process for selective catalytic reduction of NO x , and/or oxidation of one or more of carbon monoxide, nitrogen monoxide, or a hydrocarbon, the process comprising contacting one or more of NO x , carbon monoxide, nitrogen monoxide, or a hydrocarbon with the diesel oxidation catalyst of claim 1 .

11. An exhaust gas treatment system, comprising the diesel oxidation catalyst of claim 1 .

12. A process for preparing the diesel oxidation catalyst of claim 1 , wherein the diesel oxidation catalyst comprises one substrate,

the process comprising

(a) optionally disposing an intermediate slurry directly on the substrate wherein the intermediate slurry comprises alumina, thereby obtaining an intermediate slurry-treated substrate;

(b1) disposing a second slurry on the substrate, or on the intermediate slurry-treated substrate, thereby obtaining a second slurry-treated substrate,

wherein the second slurry comprises the second metal oxide and;

(c1) drying the second slurry-treated substrate;

(d1) calcining the dried second slurry-treated substrate, thereby obtaining a substrate having the second layer disposed thereon;

(e1) disposing a first slurry on the substrate having the second layer disposed thereon, thereby obtaining a first slurry-treated substrate having the second layer disposed thereon,

wherein the first slurry comprises the first metal oxide and the platinum group metal supported on titania, wherein the platinum group metal is not supported on the first metal oxide;

(f1) drying the first slurry-treated substrate having the second layer disposed thereon; and

(g1) calcining the dried first slurry-treated substrate having the second layer disposed thereon, thereby obtaining a substrate having the first and the second layer disposed thereon;

wherein the first layer is disposed, directly or indirectly, on x % of the length of the substrate from the front end of the substrate,

wherein the second layer is at least partially disposed directly on the substrate or is at least partially disposed directly on the intermediate layer which is disposed directly on the substrate over the entire length of the substrate, and

wherein the second layer is disposed, directly or indirectly, on y % of the length of the substrate from the rear end of the substrate,

wherein x is in the range of from 25 to 75 and y is in the range of from 25 to 75 and wherein x+y is in the range of from 95 to 105;

or

(a) optionally disposing an intermediate slurry directly on the substrate wherein the intermediate slurry comprises alumina, thereby obtaining an intermediate slurry-treated substrate;

(b2) disposing a first slurry on the substrate, or on the intermediate slurry-treated substrate, thereby obtaining a first slurry-treated substrate,

wherein the first slurry comprises the first metal oxide and the platinum group metal supported on titania, wherein the platinum group metal is not supported on the first metal oxide;

(c2) drying the first slurry-treated substrate;

(d2) calcining the dried first slurry-treated substrate, thereby obtaining a substrate having the first layer disposed thereon;

(e2) disposing a second slurry on the substrate having the first layer disposed thereon, thereby obtaining a second slurry-treated substrate having the first layer disposed thereon,

wherein the second slurry comprises the second metal oxide and an oxidic compound of vanadium;

(f2) drying the second slurry-treated substrate having the first layer disposed thereon; and

(g2) calcining the dried second slurry-treated substrate having the first layer disposed thereon, thereby obtaining a substrate having the first and the second layer disposed thereon;

wherein the first layer is disposed, directly or indirectly, on x % of the length of the substrate from the front end of the substrate,

wherein the second layer is at least partially disposed directly on the substrate or is at least partially disposed directly on the intermediate layer which is disposed directly on the substrate over the entire length of the substrate, and

wherein the second layer is disposed, directly or indirectly, on y % of the length of the substrate from the rear end of the substrate,

wherein x is in the range of from 25 to 75 and y is in the range of from 25 to 75 and wherein x+y is in the range of from 95 to 105.

13. A diesel oxidation catalyst obtained by the process of claim 12 .