Scr catalyst

Patent metadata

Field	Value
Publication number	US-2016288094-A1
Application number	US-201415035640-A
Country	US
Kind code	A1
Filing date	Nov 19, 2014
Priority date	Nov 25, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

The invention relates to a catalyst comprising at least two catalytically active layers, A and B, wherein A contains a carrier oxide and components A1 and A2, and B contains a carrier oxide and components B1, B2, and B3, wherein A1, A2, and B1 to B3 are defined as disclosed in claim 1. The proportion of component A1 in layer A is thereby greater than the proportion of component B1 in layer B, wherein the proportion of layer A with respect to the total weight of layers A and B, is greater than the proportion of layer B. The invention further relates to a method for reducing nitrogen oxides in exhaust gases of lean-burn internal combustion engines and to an exhaust gas cleaning system.

First claim

1 . A catalyst for the selective reduction of nitrogen oxides comprising two catalytically active layers A and B, wherein
A contains a carrier oxide and the components A1 and A2, and B contains a carrier oxide and the components B1, B2, and B3, wherein A1 and B1 stand for at least one oxide of vanadium, A2 and B2 for at least one oxide of tungsten, and B3 for at least one oxide of silicon, characterized in that
the proportion of component A1 in layer A in wt % with respect to the total weight of layer A is greater than the proportion of component B1 in layer B in wt % with respect to the total weight of layer B, and
the proportion of layer A in wt % with respect to the total weight of layers A and B is greater than the proportion of layer B.

2 . The catalyst according to claim 1 , characterized in that layer A, in addition to components A1 and A2, contains a component A3, wherein A3 stands for at least one oxide of silicon, and wherein the proportion of component A3 in layer A in wt % with respect to the total weight of layer A is smaller than the proportion of component B3 in layer B in wt % with respect to the total weight of layer B.

3 . The catalyst according to claim 1 , characterized in that it comprises at least two catalytically active layers A and B, wherein
A contains a carrier oxide, vanadium pentoxide as component A1, and tungsten trioxide as component A2, and B contains a carrier oxide, vanadium pentoxide as component B1, tungsten trioxide as component B2, and silicon dioxide as component B3, characterized in that
the proportion of vanadium pentoxide in layer A in wt % with respect to the total weight of layer A is greater than the proportion of vanadium pentoxide in layer B in wt % with respect to the total weight of layer B, and
the proportion of layer A in wt % with respect to the total weight of layers A and B is greater than the proportion of layer B.

4 . The catalyst according to claim 1 , characterized in that the proportion of component A2 in layer A and component B2 in layer B in wt % respectively with respect to the total weight of layer A or B is equal, or the proportion of component A2 in layer A in wt % with respect to the total weight of layer A is smaller than the proportion of component B2 in layer B in wt % with respect to the total weight of layer B.

5 . The catalyst according to claim 1 , characterized in that the proportion of component A1 calculated as vanadium pentoxide amounts to 1.5 to 5 wt %—in particular, 2 to 4 wt %—with respect to the total weight of layer A.

6 . The catalyst according to claim 1 , characterized in that the proportion of component B1 calculated as vanadium pentoxide amounts to 1 to 4 wt %—in particular, 1.5 to 3.5 wt %—with respect to the total weight of layer B.

7 . The catalyst according to claim 1 , characterized in that the proportion of component A2 with respect to the total weight of layer A and the proportion of component B2 with respect to the total weight of layer B are equal and, calculated as tungsten trioxide, amounts to 3 to 12—preferably 4.5 to 10—wt %.

8 . The catalyst according to claim 1 , characterized in that the proportion of component A2 with respect to the total weight of layer A is smaller than the proportion of component B2 with respect to the total weight of layer B and, calculated as tungsten trioxide, amounts to 3 to 5.5—preferably 4.5 to 5—wt %, wherein the proportion of component B2 with respect to the total weight of layer B amounts to 4.5 to 12—preferably 5 to 10—wt %.

9 . The catalyst according to claim 1 , characterized in that the proportion of component B3 with respect to the total weight of layer B and calculated as silicon dioxide amounts to 3 to 12—preferably 3.5 to 10—wt %.

10 . The catalyst according to claim 1 , characterized in that the proportion of component A3 with respect to the total weight of layer A and calculated as silicon dioxide amounts to 0 to 5 wt %.

11 . The catalyst according to claim 1 , characterized in that
the proportion of component A1 calculated as vanadium pentoxide amounts to 1.5 to 5 wt % with respect to the total weight of layer A, and the proportion of component B1 calculated as vanadium pentoxide amounts to 1 to 4 wt % with respect to the total weight of layer B, and the proportion of component A2 with respect to the total weight of layer A and the proportion of component B2 with respect to the total weight of layer B are equal and, calculated as tungsten trioxide, amount to 3 to 12 wt %, or the proportion of component A2 with respect to the total weight of layer A is smaller than the proportion of component B2 with respect to the total weight of layer B and, calculated as tungsten trioxide, amounts to 3 to 5.5 wt %, wherein the proportion of component B2 with respect to the total weight of layer B amounts to 4.5 to 12 wt %, and the proportion of component B3 with respect to the total weight of layer B and calculated as silicon dioxide amounts to 3 to 12 wt %, wherein component A3 is not present, or its proportion with respect to the total weight of layer A and calculated as silicon dioxide amounts to 1 to 5 wt %.

12 . The catalyst according to claim 1 , characterized in that
the proportion of component A1 calculated as vanadium pentoxide amounts to 2 to 4 wt % with respect to the total weight of layer A, and the proportion of component B1 calculated as vanadium pentoxide amounts to 1.5 to 3.5 wt % with respect to the total weight of layer B, and the proportion of component A2 with respect to the total weight of layer A and the proportion of component B2 with respect to the total weight of layer B are equal and, calculated as tungsten trioxide, amount to 4.5 to 10 wt %, or the proportion of component A2 with respect to the total weight of layer A is smaller than the proportion of component B2 with respect to the total weight of layer B and, calculated as tungsten trioxide, amounts to 4.5 to 5 wt %, wherein the proportion of component B2, with respect to the total weight of layer B, amounts to 5 to 10 wt %, and the proportion of component B3 with respect to the total weight of layer B and calculated as silicon dioxide amounts to 3.5 to 10 wt %, wherein component A3 is not present, or its proportion with respect to the total weight of layer A and calculated as silicon dioxide amounts to 1 to 5 wt %.

13 . The catalyst according to claim 1 , characterized in that layers A and B, independently of each other, contain additional components A4 or B4, wherein
A4 stands for one or more metal oxides which are selected from the series consisting of oxides of copper, iron, manganese, molybdenum, antimony, niobium, silver, palladium, platinum, and rare earth elements, and B4, independently of A4, stands for one or more metal oxides which are selected from the series consisting of oxides of copper, iron, manganese, molybdenum, antimony, niobium, silver, and rare earth elements.

14 . The catalyst according to claim 13 , characterized in that the proportion of component A4 with respect to the total weight of layer A amounts to 0.1 to 15 wt %, wherein, in the case of silver, platinum and palladium, the proportion is calculated as metal in each case, and in the case of the remaining components, the proportion is calculated as oxides in each case, namely, as CuO, Fe 2 O 3 , MnO, MoO 3 , Sb 2 O 5 , Nb 2 O 5 , CeO 2 , or Er 2 O 3 .

15 . The catalyst according to claim 1 , characterized in that the carrier oxide in layer A and/or B contains titanium dioxide, zirconium dioxide, aluminum oxide, or mixtures thereof.

16 . The catalyst according to claim 1 m

Assignees

• Umicore Ag & Co Kg

Inventors

• Malmberg Stephan
• Soeger Nicola
• Demel Yvonne
• Jeske Gerald

Classifications

• B01D2255/9155

  Wall flow filters · CPC title

• B01D2255/40

  Mixed oxides · CPC title

• B01D2258/012

  Diesel engines and lean burn gasoline engines · CPC title

• B01D2255/9022

  Two layers · CPC title

• B01D2255/30

  Silica · CPC title