Cu-CHA/Fe-MFI mixed zeolite catalyst and process for the treatment of NOx in gas streams

Patent metadata

Field	Value
Publication number	US-9352307-B2
Application number	US-201113082907-A
Country	US
Kind code	B2
Filing date	Apr 8, 2011
Priority date	Apr 8, 2010
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

Described is a catalyst, preferably for use in selective catalytic reduction (SCR), said catalyst comprising one or more zeolites of the MFI structure type, and one or more zeolites of the CHA structure type, wherein at least part of the one or more zeolites of the MFI structure type contain iron (Fe), and wherein at least part of the one or more zeolites of the CHA structure type contain copper (Cu). An exhaust gas treatment system is described, comprising said catalyst as well as a process for the treatment of a gas stream comprising NO x using said catalyst as well.

First claim

The invention claimed is:

1. A catalyst for use in selective catalytic reduction (SCR), said catalyst comprising:
one or more zeolites of the MFI structure type, and
one or more zeolites of the CHA structure type,
wherein at least part of the one or more zeolites of the MFI structure type contain iron (Fe),
wherein at least part of the one or more zeolites of the CHA structure type contain copper (Cu),
wherein the weight ratio of the one or more zeolites of the MFI structure type relative to the one or more zeolites of the CHA structure type ranges from 1:2 to 2:1,
wherein the molar ratio of silica to alumina (SAR) in the one or more zeolites of the MFI structure type ranges from 20 to 50,
wherein the molar ratio of silica to alumina (SAR) in the one or more zeolites of the CHA structure type ranges from 20 to 55,
wherein the amount of Fe in the one or more zeolites of the MFI structure type ranges from 2.5 to 5.5 wt-% based on the weight of said one or more zeolites, and
wherein the amount of Cu in the one or more zeolites of the CHA structure type ranges from 1.0 to 1.0 wt-% based on the weight of said one or more zeolites.

2. The catalyst of claim 1 , wherein said catalyst further comprises a honeycomb substrate onto which the one or more zeolites are provided.

3. The catalyst of claim 2 , wherein the substrate is selected from the group consisting of flow-through substrates and wall-flow substrates.

4. The catalyst of claim 2 , wherein the catalyst comprises one or more washcoat layers provided on the substrate, the zeolites being contained in one single layer.

5. The catalyst of claim 2 , wherein either the one or more zeolites of the MFI structure type, or the one or more zeolites of the CHA structure type, or both the one or more zeolites of the MFI structure type and the one or more zeolites of the CHA structure type, are respectively present in the catalyst in a loading ranging from 0.1 to 5.0 g/in 3 .

6. The catalyst of claim 1 , wherein the molar ratio of silica to alumina (SAR) in the one or more zeolites of the MFI structure type ranges from 23 to 30.

7. The catalyst of claim 1 , wherein the molar ratio of silica to alumina (SAR) in the one or more zeolites of the CHA structure type ranges from 25 to 35.

8. The catalyst of claim 1 , wherein the amount of Cu in the one or more zeolites of the CHA structure type ranges from 1.6 to 3.4 wt-% based on the weight of said one or more zeolites.

9. The catalyst of claim 2 , wherein either the one or more zeolites of the MFI structure type, or the one or more zeolites of the CHA structure type, or both the one or more zeolites of the MFI structure type and the one or more zeolites of the CHA structure type, are respectively present in the catalyst in a loading ranging from 1.25 to 1.45 g/in 3 .

10. An exhaust gas system comprising the catalyst of claim 1 , an internal combustion engine and an exhaust gas conduit in fluid communication with the internal combustion engine, wherein said catalyst is present in the exhaust gas conduit, and wherein the internal combustion engine is a lean burn engine.

11. An exhaust gas treatment system comprising an internal combustion engine and an exhaust gas conduit in fluid communication with the internal combustion engine, wherein a catalyst according to claim 1 is present in the exhaust gas conduit, and wherein the internal combustion engine is a diesel engine.

12. The exhaust gas treatment system of claim 11 , said exhaust gas treatment system further comprising an oxidation catalyst and/or a catalyzed soot filter (CSF), wherein the oxidation catalyst and/or the CSF are located upstream from the catalyst according to claim 1 , and wherein the oxidation catalyst is a diesel oxidation catalyst (DOC).

13. A process for the treatment of a gas stream comprising NO x comprising conducting said gas stream over a catalyst according to claim 1 , wherein the gas stream is an exhaust gas stream or a diesel exhaust gas stream.

14. The process for the treatment of a gas stream comprising NO x according to claim 13 , wherein the gas stream comprises ammonia and/or urea.

15. The process for the treatment of a gas stream comprising NO according to claim 13 , wherein prior to the contacting of the catalyst with the gas stream, the NO 2 content thereof is 80 wt-% or less based on 100 wt.-% of NO x .

Assignees

• Stiebels Susanne
• Wendt Claudia
• Neubauer Torsten
• Dieterle Martin
• Mohanan Jaya L
• Basf Corp

Inventors

• Stiebels Susanne
• Wendt Claudia
• Neubauer Torsten
• Dieterle Martin
• Mohanan Jaya L

Classifications

• B01D2255/9022

  Two layers · CPC title

• B01D2255/50

  Zeolites · CPC title

• B01J29/46

  Iron group metals or copper · CPC title

• B01D2258/012

  Diesel engines and lean burn gasoline engines · CPC title

• B01D2255/504

  ZSM 5 zeolites · CPC title