US 8,507,404 B2 · Regenerable sulfur traps for on-board vehicle applications

Abstract

Provided are improved regenerable SOx trap formulations for on-board vehicle applications. The regenerable sulfur trap formulations reduce the rate of sulfur poisoning of a downstream nitrogen storage reduction (NSR) catalyst trap in exhaust gas cleaning systems for combustion engines by adsorbing SOx as metal sulfate under lean exhaust conditions and desorbing the accumulated SOx under rich exhaust conditions. The regenerable sulfur oxides trap catalyst compositions include a metal (M) oxide, wherein M is selected from Cu, Fe, Mn, Ag, Co and combinations thereof and a metal (M)-La—Zr oxide, wherein M is selected from Cu, Fe, Mn, Ag, Co and combinations thereof. In addition, provided are improved exhaust gas cleaning systems and methods for treating exhaust gas from a combustion source that include a hydrogen generation system, a regenerable sulfur oxides trap, and a regenerable nitrogen storage reduction (NSR) catalyst trap. The improved exhaust gas cleaning systems and methods allow for the sulfur released from the sulfur trap to pass through the nitrogen oxide trap with no or little poisoning of NOx storage and reduction sites, which significantly improves NSR catalyst trap lifetime and performance to meet future emissions standards. The disclosed exhaust gas cleaning systems are suitable for use in internal combustion engines (e.g., diesel, gasoline, CNG) which operate with lean air/fuel ratios over most of the operating period.

Claims5

Dependent claims

A regenerable sulfur oxides trap catalyst product composition containing adsorbed sulfur and made according to a process comprising:

providing a fresh or regenerated sulfur oxides trap catalyst composition comprising a Mn—La—Zr oxide on a catalyst support (S), wherein the catalyst support (S) is selected from the group consisting of alumina, stabilized gamma alumina with rare earth components, MCM-41, zeolites, silica, magnesia, zirconia, ceria, ceria-zirconia, titania, titania-zirconia, and combinations thereof;
exposing the sulfur oxides trap catalyst composition to a combustion source containing SOx under lean exhaust conditions sufficient for the sulfur oxides trap catalyst to adsorb the SOx by converting a Mn—La—Zr oxide site into a Mn—La—Zr sulfate, the conditions comprising an adsorption temperature from 200° C. to 600° C. and an oxidative environment, thus forming a regenerable sulfur oxides trap catalyst product composition containing adsorbed sulfur,
wherein at least one of the following are satisfied:
the Mn—La—Zr oxide comprises from 1 wt % to 25 wt % Mn, from 1 wt % to 10 wt % La, from 20 wt % to 60 wt % Zr, and the remaining wt % oxygen;
the Mn—La—Zr oxide further comprises yttrium, cerium, lithium, potassium, or combinations thereof;
and
the Mn—La—Zr oxide is supported on alumina in an amount from 5 wt % to 90 wt %.

4 more elements

Dependencies are inferred from the claim text.

Regenerable sulfur traps for on-board vehicle applications

Life of this patent

Regenerable sulfur traps for on-board vehicle applications

Life of this patent

Abstract

Claims5