# US 10,119,445 B2 · Exhaust system with a modified lean NOx trap

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- Number: US 10,119,445 B2
- Document ID: US10119445B2
- Status: Granted
- Kind: B2
- Application number: 14/487,195
- Filed: 2014-09-16
- Published: 2015-03-19
- Granted: 2018-11-06
- Earliest claimed: 2013-09-16
- Assignees: Johnson Matthey Public Limited Company
- Applicants: Johnson Matthey Public Limited Company
- Inventors: Daniel Swallow
- Web page: https://patentgrep.com/patent/US10119445B2

## CPC

- F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent}
- B01D 53/9418: {for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas}
- B01D 53/9481: {Catalyst preceded by an adsorption device without catalytic function for temporary storage of contaminants, e.g. during cold start}
- F01N 3/035: with catalytic reactors
- F01N 3/0807: {by using absorbents or adsorbents}
- F01N 3/0842: {Nitrogen oxides}
- F01N 3/0885: {Regeneration of deteriorated absorbents or adsorbents, e.g. desulfurization of NOx traps}
- F01N 13/009: {having two or more separate purifying devices arranged in series}
- B01D 53/9431: {Processes characterised by a specific device}
- B01D 2255/20707: Titanium
- B01D 2255/20723: Vanadium
- B01D 2255/20738: Iron
- B01D 2255/20761: Copper
- B01D 2255/20776: Tungsten
- B01D 2255/502: Beta zeolites
- B01D 2255/504: ZSM 5 zeolites
- F01N 3/0814: {combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts}
- F01N 2370/02: used in catalytic reactors
- F01N 2430/085: at least a part of the injection taking place during expansion or exhaust stroke
- F01N 2510/06: for exhaust purification, e.g. catalytic reaction
- F01N 2610/02: the substance being ammonia or urea
- Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
- Y02T 10/12: Improving ICE efficiencies
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An exhaust system for treating an exhaust gas from an internal combustion engine is disclosed. The system comprises a modified lean NOx trap (LNT), a urea injection system, and an ammonia-selective catalytic reduction (NH3-SCR) catalyst. The modified LNT comprises platinum, palladium, barium, and a ceria-containing material, and has a platinum:palladium molar ratio of at least 3:1. The modified LNT stores NOx at temperatures below about 200° C. and releases the stored NOx at temperatures above about 200° C. The urea injection system injects urea at temperatures above about 180° C.

## Claims

### Claim 1

An exhaust system for treating an exhaust gas from an internal combustion engine, comprising:
(a) NOx treatment catalysts, and
(b) a urea injection system;
wherein the NOx treatment catalysts consist essentially of a single layer lean NOx trap (LNT), comprising platinum, palladium, barium, and a ceria-containing material and a platinum:palladium molar ratio of at least 3:1; and an ammonia-selective catalytic reduction (NH3-SCR) catalyst;
wherein the urea injection system is upstream of the NH3-SCR catalyst and downstream of the LNT; and
wherein the LNT stores NOx at temperatures below about 200° C. and releases the stored NOx at temperatures above about 200° C.

### Claim 2 (depends on 1)

The exhaust system of claim 1 wherein the urea injection system injects urea at temperatures above about 180° C.

### Claim 3 (depends on 1)

The exhaust system of claim 1 wherein the LNT has a platinum:palladium molar ratio of at least 4:1.

### Claim 4 (depends on 1)

The exhaust system of claim 1 wherein the LNT has a barium loading of greater than 150 g/ft3.

### Claim 5 (depends on 1)

The exhaust system of claim 1 wherein the LNT has a barium loading of greater than 400 g/ft3.

### Claim 6 (depends on 1)

The exhaust system of claim 1 wherein the NH3-SCR catalyst is selected from the group consisting of a vanadia-titania catalyst, a vanadia-tungsta-titania catalyst, and a metal/zeolite.

### Claim 7 (depends on 6)

The exhaust system of claim 6 wherein the metal/zeolite comprises a metal selected from the group consisting of iron or copper and a zeolite selected from the group consisting of a beta zeolite, a faujasite, an L-zeolite, a ZSM zeolite, an SSZ-zeolite, a ferrierite, a mordenite, a chabazite, an offretite, an erionite, a clinoptilolite, a silicalite, an aluminum phosphate zeolite, and a mesoporous zeolite.

### Claim 8 (depends on 1)

The exhaust system of claim 1 wherein the NH3-SCR catalyst is an ammonia-selective catalytic reduction filter (NH3-SCRF).

### Claim 9 (depends on 8)

The exhaust system of claim 8 wherein the NH3-SCRF comprises a filter having a NH3-SCR catalyst selected from the group consisting of a vanadia-titania catalyst, a vanadia-tungsta-titania catalyst, and a metal/zeolite.