A SELECTIVE CATALYTIC REDUCTION CATALYST FOR THE TREATMENT OF AN EXHAUST GAS

Abstract

The present invention relates to a selective catalytic reduction catalyst for the treatment of an exhaust gas of a combustion engine, the catalyst comprising 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; a coating disposed on the substrate (i), the coating comprising a first non-zeolitic oxidic material comprising aluminum, an 8-membered ring pore zeolitic material comprising one or more of copper and iron, and a second non-zeolitic oxidic material comprising cerium and one or more of zirconium, aluminum, silicon, lanthanum, niobium, iron, manganese, titanium, tungsten, copper, molybdenum, neodymium, cobalt, chromium, tin and praseodymium; wherein at least 65 weight-% of the coating consist of the 8-membered ring pore zeolitic material comprising one or more of copper and iron.

Claims

1-15. (canceled)

16. A selective catalytic reduction catalyst for treating an exhaust gas of a combustion engine, the catalyst 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; (ii) a coating disposed on the substrate (i), the coating comprising a first nonzeolitic oxidic material comprising aluminum, a second non-zeolitic oxidic material comprising cerium and one or more of zirconium, aluminum, silicon, lanthanum, niobium, iron, manganese, titanium, tungsten, copper, molybdenum, neodymium, cobalt, chromium, tin and praseodymium, and the coating further comprising an 8-membered ring pore zeolitic material comprising one or more of copper and iron; wherein at least 65 weight-% of the coating consist of the 8-membered ring pore zeolitic material comprising one or more of copper and iron.

17. The catalyst of claim 16, wherein the first non-zeolitic oxidic material comprises alumina, wherein from 98 weight-% to 100 weight-%, of the first nonzeolitic material consist of alumina, and wherein the first non-zeolitic material has a BET specific surface area in the range of from 120 m.sup.2/g to 300 m.sup.2/g.

18. The catalyst of claim 16, wherein the first non-zeolitic oxidic material further comprises one or more of zirconium, silicon and titanium.

19. The catalyst of claim 16, wherein the first non-zeolitic oxidic material is comprised in the coating (ii) in an amount ranging from 2 weight-% to 28 weight-%, based on the weight of the 8-membered ring pore zeolitic material.

20. The catalyst of claim 16, wherein the second non-zeolitic oxidic material comprised in the coating (ii) comprises a mixed oxide of cerium and one or more of zirconium, aluminum, silicon, lanthanum, niobium, iron, manganese, titanium, tungsten, copper, molybdenum, neodymium, cobalt, chromium, tin and praseodymium, or a mixture of a cerium oxide and an oxide of one or more of zirconium, aluminum, silicon, lanthanum, niobium, iron, manganese, titanium, tungsten, copper, molybdenum, neodymium, cobalt, chromium, tin, and praseodymium.

21. The catalyst of claim 20, wherein the second non-zeolitic oxidic material comprised in the coating (ii) comprises a mixed oxide of cerium and one or more of zirconium, aluminum, silicon, lanthanum, niobium, iron, manganese, titanium, tungsten, copper, molybdenum, neodymium, cobalt, chromium, tin and praseodymium.

22. The catalyst of claim 21, wherein the mixed oxide of cerium and zirconium has a crystalline phase Ce.sub.aZr.sub.1-aO.sub.2, wherein a ranges from 0.1 to 0.9.

23. The catalyst of claim 20, wherein the second non-zeolitic oxidic material comprised in the coating (ii) comprises a mixture of a cerium oxide and one or more of a zirconium oxide, an aluminum oxide, a silicon oxide, a lanthanum oxide, a niobium oxide, an iron oxide, a manganese oxide, a titanium oxide, a tungsten oxide, a copper oxide, a molybdenum oxide, a neodymium oxide, a cobalt oxide, a chromium oxide, a tin oxide and a praseodymium oxide.

24. The catalyst of claim 16, wherein a ratio of the weight of the first non-zeolitic oxidic material, (w1), to the weight of the second non-zeolitic oxidic material, (w2), defined as (w1):(w2), ranges from 0.2:1 to 0.7:1.

25. The catalyst of claim 16, wherein the 8-membered ring pore zeolitic material comprised in the coating (ii) has a framework type selected from the group consisting of CHA, AEI, RTH, LEV, DDR, KFI, ERI, AFX, LTA, a mixture of two or more thereof, and a mixed type of two or more thereof.

26. The catalyst of claim 16, wherein the 8-membered ring pore zeolitic material comprised in the coating (ii), having a framework type CHA, comprises crystals having an average crystal size in the range of from 0.05 micrometers to 5 micrometers.

27. The catalyst of claim 16, wherein the substrate is a wall-flow filter substrate or a flow-through substrate.

28. A process for preparing a selective catalytic reduction catalyst for treating an exhaust gas of a combustion engine, the process comprising (a) preparing a mixture comprising water, a first non-zeolitic oxidic material comprising aluminum, a second non-zeolitic oxidic material comprising cerium and one or more of zirconium, aluminum, silicon, lanthanum, niobium, iron, manganese, titanium, tungsten, copper, molybdenum, neodymium, cobalt, chromium, tin and praseodymium, and an 8-membered ring pore zeolitic material comprising one or more of copper and iron; (b) disposing the mixture obtained according to (a) on a 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, obtaining a mixture-treated substrate; (c) calcining the mixture-treated substrate obtained according to (b), obtaining the substrate having a coating disposed thereon, wherein at least 65 weight-% of the coating consist of the 8-membered ring pore zeolitic material comprising one or more of copper and iron.

29. The process of claim 28, wherein (b) further comprising (b.1) disposing a first portion of the mixture obtained in (a) on 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, the disposing being from the inlet end toward the outlet end of the substrate; and drying the substrate comprising the first portion of the mixture disposed thereon; and (b.2) disposing a second portion of the mixture obtained in (i) on the substrate comprising the first portion of the mixture disposed thereon obtained in (b.2), the disposing being from the inlet end toward the outlet end of the substrate; and drying the substrate comprising the first and the second portion of the mixture disposed thereon.

30. An exhaust gas treatment system for treating an exhaust gas stream exiting a combustion engine, wherein 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 first selective catalytic reduction catalyst according to claim 16, and one or more of a diesel oxidation catalyst, a second selective catalytic reduction catalyst, an ammonia oxidation catalyst, a diesel oxidation catalyst containing a NO.sub.X storage function, and a particulate filter.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0282] FIG. 1 shows the NO.sub.X conversion measured for the catalysts of Examples 1-3, of Comparative Example 1 and of Reference Example 5 at 200° C. (20 ppm NH.sub.3 slip—space velocity of 40 k/h).

[0283] FIG. 2 shows the backpressure measured for the catalysts of Examples 1-3, of Comparative Example 1 and of Reference Example 5 at 293 K (flow rate 27 m.sup.3/h).

[0284] FIG. 3 shows the NO.sub.X conversion measured for the catalysts of Examples 5 and 6, and of Comparative Example 2 at 200° C. (20 ppm NH.sub.3 slip—space velocity of 40 k/h and 80 k/h).

[0285] FIG. 4 shows the NO.sub.X conversion measured for the catalysts of Examples 5 and 6, and of Comparative Example 2 at 600° C. (20 ppm NH.sub.3 slip—space velocity of 40 k/h and 80 k/h).

[0286] FIG. 5 shows the NO.sub.X conversion measured for the catalysts of Reference Examples 6.1-6.3 at 575° C. (20 ppm NH.sub.3 slip—space velocity of 94 k/h).

[0287] FIG. 6 shows the backpressure measured for the catalysts of Reference Examples 6.1-6.3 at 293 K (flow rate 65 m.sup.3/h).

[0288] FIG. 7 shows the XRD analysis of Examples 1 to 3.

[0289] FIG. 8 shows the XRD analysis of Example 5.

CITED LITERATURE

[0290] US 2011/0142737 A1 [0291] DE 102011012799 A1 [0292] US 2013/0156668 A1