MULTI-FUNCTIONAL CATALYSTS FOR THE OXIDATION OF NO, THE OXIDATION OF NH3 AND THE SELECTIVE CATALYTIC REDUCTION OF NOX

Abstract

The present invention relates to a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, comprising a substrate, a first coating comprising one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron; and a second coating comprising a platinum group metal component supported on a non-zeolitic oxidic material, wherein the second coating further comprises a zeolitic material comprising one or more of copper and iron.

Claims

1-15. (canceled)

16. A catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, comprising: (i) a substrate comprising an inlet end, an outlet end, a substrate axial length extending from the inlet end to the outlet end, and a plurality of passages defined by internal walls of the substrate extending therethrough, wherein the interface between the passages and the internal walls is defined by the surface of the internal walls; (ii) a first coating comprising one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron; (iii) a second coating comprising a platinum group metal component supported on a non-zeolitic oxidic material, wherein the platinum group metal component supported on the non-zeolitic oxidic material is present in the second coating at a first loading L1, wherein the first loading is a sum of the loading of the platinum group metal component and the loading of the non-zeolitic oxidic material; the second coating further comprising a zeolitic material comprising one or more of copper and iron, wherein the zeolitic material comprising one or more of copper and iron is present in the second coating at a second loading L2, wherein the second loading is a sum of the loading of the zeolitic material and the loading of the one or more of copper and iron; wherein the second coating is disposed on the surface of the internal walls over y % of the axial length of the substrate from the outlet end to the inlet end, with y ranging from 10 to 90; wherein the first coating extends over x % of the axial length of the substrate from the inlet end to the outlet end and is disposed on the second coating and on the surface of the internal walls, with x ranging from 95 to 100; wherein the ratio of the first loading, in g/l, to the second loading, in g/l, L1:L2, is of at least 1.1:1.

17. The catalyst of claim 16, wherein the first coating (ii) comprises a zeolitic material comprising one or more of copper and iron.

18. The catalyst of claim 16, wherein the zeolitic material comprised in the first coating has a framework type selected from the group consisting of AEI, GME, CHA, MFI, BEA, FAU, MOR, a mixture of two or more thereof, and a mixed type of two or more thereof.

19. The catalyst of claim 16, wherein the zeolitic material comprised in the first coating comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, ranges from 1 to 10 weight-%, based on the total weight of the zeolitic material.

20. The catalyst of claim 16, wherein from 0 weight-%to 0.001 weight-% of the first coating consist of platinum.

21. The catalyst of claim 16, wherein the platinum group metal component comprised in the second coating is one or more of platinum, palladium and rhodium; and wherein the second coating comprises the platinum group metal component at a loading, calculated as elemental platinum group metal, in the range of from 2 to 50 g/ft.sup.3.

22. The catalyst of claim 16, wherein the non-zeolitic oxidic material onto which the platinum group metal component of the second coating is supported comprises one or more of alumina, zirconia, titania, silica, ceria, and a mixed oxide comprising two or more of Al, Zr, Ti, Si, and Ce.

23. The catalyst of claim 16, wherein the second coating comprises the non-zeolitic oxidic material at a loading ranging from 0.25 to 3 g/in.

24. The catalyst of claim 18, wherein the zeolitic material comprised in the second coating has a framework type selected from the group consisting of AEI, GME, CHA, MFI, BEA, FAU, MOR, a mixture of two or more thereof, and a mixed type of two or more thereof.

25. The catalyst of claim 18, wherein the zeolitic material comprised in the second coating comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, ranges from 3 weight-% to 6 weight-%, based on the total weight of the zeolitic material.

26. The catalyst of claim 18, wherein, in the second coating, the ratio of the first loading, in g/l, to the second loading, in g/l, L1:L2, ranges from 1.1:1 to 50:1.

27. A method for preparing a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx comprising: (a) providing an uncoated substrate, wherein the substrate comprising an inlet end, an outlet end, a substrate axial length extending from the inlet end to the outlet end and a plurality of passages defined by internal walls of the substrate extending therethrough, and wherein the interface between the passages and the internal walls is defined by the surface of the internal walls; (b) providing a slurry comprising a solvent, a platinum group metal component, a non-zeolitic oxidic material, and a zeolitic material comprising one or more of copper and iron, disposing the slurry on the surface of the internal walls over y % of the substrate axial length from the outlet end to the inlet end, with y ranging from 10 to 90, calcining the slurry disposed on the substrate, obtaining a second coating disposed on the surface of the internal walls of the substrate; and (c) providing a slurry comprising a solvent and one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron, disposing the slurry over x % of the substrate axial length on the second coating from the inlet end to the outlet end, with x ranging from 95 to 100, calcining the slurry disposed on the substrate, obtaining a first coating disposed on the surface of the internal walls of the substrate and on the second coating.

28. The method of claim 27, wherein (b) comprises: (b.1) forming a slurry with an aqueous mixture of water, a platinum group metal precursor, a non-zeolitic oxidic material, and a zeolitic material comprising one or more of copper and iron; (b.2) adding a precursor of a second oxidic material; (b.3) disposing the slurry obtained in (b.1) or (b.2), on the surface of the internal walls over y % of the substrate axial length from the outlet end to the inlet end of the substrate; (b.4) drying the slurry disposed on the substrate obtained in (b.3), obtaining a dried slurry-treated substrate; and (b.5) calcining the slurry disposed on the substrate obtained in (b.3) or (b.4), in a gas atmosphere having a temperature in the range of from 300° C. to 600° C.

29. An exhaust gas treatment system for treating an exhaust gas stream exiting an internal combustion engine, the exhaust gas treatment system having an upstream end for introducing the exhaust gas stream into the exhaust gas treatment system, wherein the exhaust gas treatment system comprises a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx according to claim 16, and one or more of a selective catalytic reduction catalyst, a combined selective catalytic reduction/ammonia oxidation catalyst, and a catalyzed soot filter.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0239] FIG. 1 shows the deNOx performance of the catalyst of Example 1 and of Comparative Example 1 at inlet temperatures ranging from 200 to 450° C. and at ANR = 1.1.

[0240] FIG. 2 shows the nitrous oxide formation measured for the catalysts of Example 1 and of Comparative Example 1 at inlet temperatures ranging from 200 to 450° C. and at ANR = 1.0.

[0241] FIG. 3 shows the ammonia slip of the catalysts of Example 1 and of Comparative Example 1 at inlet temperatures ranging from 200 to 450° C.

[0242] FIG. 4 shows the NO oxidation (NO.sub.2/NOx ratio) of the catalysts of Example 1 and of Comparative Example 1 at inlet temperatures of from about 200 to 450° C. and a SV of 100 k/h.

[0243] FIG. 5 shows a schematic depiction of a catalyst according to the present invention (a) and a catalyst not according to the present invention (b), the catalyst of Comparative Example 1. In particular, this figure shows (a) a catalyst 1 of the present invention comprising a substrate 2, such as a flow-through substrate, onto which an outlet coating 3, the second coating of the present invention, is disposed over 67 % of the substrate axial length from the outlet end to the inlet end of the substrate. The catalyst 1 further comprises a top coating 4 disposed onto the surface of the internal walls of the substrate 2 and on the coating 3 (second coating) over the entire length of the substrate. Further, this figure shows (b) a catalyst 20 not according to the present invention comprising a substrate 2, such as a flow-through substrate, onto which an inlet coating 5, the second coating of the catalyst of Comparative Example 1, is disposed over 50 % of the substrate axial length from the inlet end to the outlet end of the substrate and an outlet coating 6, the third coating of the catalyst of Comparative Example 1, is disposed over 50 % of the substrate axial length from the outlet end to the inlet end. The catalyst 20 further comprises a top coating 7 disposed onto the coating 5 and the coating 6 over the entire length of the substrate.

CITED LITERATURE

[0244] U.S. 2018/0280876 A1 [0245] U.S. 2018/0280877 A1