# US 2019/0168161 A1 · Monometallic rhodium-containing four-way conversion catalysts for gasoline engine emissions treatment systems

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- Number: US 2019/0168161 A1
- Document ID: US20190168161A1
- Status: Published application
- Kind: A1
- Application number: 16/323,148
- Filed: 2017-07-25
- Published: 2019-06-06
- Earliest claimed: 2016-08-05
- Assignees: BASF SE
- Applicants: BASF SE
- Inventors: Janosch CRAVILLON; Stephan SIEMUND; Attilio SIANI; Thomas SCHMITZ; Markus KINNE
- Web page: https://patentgrep.com/patent/US20190168161A1

## CPC

- B01D 53/945: {characterised by a specific catalyst}
- B01D 53/9477: {with catalysts positioned on separate bricks, e.g. exhaust systems}
- B01J 23/464: {Rhodium}
- B01J 23/63: with rare earths or actinides
- B01J 35/19: {Catalysts containing parts with different compositions}
- B01J 35/56: Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional [3D] monoliths
- B01J 35/66: Pore distribution
- B01J 37/0244: {Coatings comprising several layers}
- F01N 3/035: with catalytic reactors
- F01N 3/101: {Three-way catalysts}
- B01D 2255/1025: Rhodium
- B01D 2255/2065: Cerium
- B01D 2255/407: Zr-Ce mixed oxides
- B01D 2255/908: O2-storage component incorporated in the catalyst
- B01D 2255/9155: Wall flow filters
- B01D 2258/014: Stoichiometric gasoline engines
- F01N 2330/06: Ceramic, e.g. monoliths
- F01N 2510/06: for exhaust purification, e.g. catalytic reaction
- F01N 2510/068: characterised by the distribution of the catalytic coatings
- F01N 2510/0684: having more than one coating layer, e.g. multi-layered coatings
- Y02T 10/12: Improving ICE efficiencies
- 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)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- 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)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Catalyzed particulate filters comprise three-way conversion (TWC) catalytic material, which comprises rhodium as the only platinum group metal, that permeates walls of a particulate filter. Such catalyzed particulate filters may be located downstream of close-coupled three-way conversion (TWC) composites in an emission treatment system downstream of a gasoline direct injection engine for treatment of an exhaust stream comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates.

## Claims

### Claim 1

An emission treatment system downstream of a gasoline direct injection engine for treatment of an exhaust stream comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates, the emission treatment system comprising:
a close-coupled three-way conversion (TWC) composite comprising a first TWC catalytic material on a flow-through substrate; and
an catalyzed particulate filter located downstream of the close-coupled TWC composite, the catalyzed particulate filter comprising a second TWC catalytic material that permeates walls of a particulate filter,
wherein the second TWC catalytic material comprises rhodium as the only platinum group metal.

### Claim 2 (depends on 1)

The emission treatment system of claim 1, wherein the particulate filter comprises a mean pore diameter of about 13 to about 25 μm.

### Claim 3 (depends on 1)

The emission treatment system of claim 1, wherein:
the particulate filter has a wall thickness of about 6 mils (152 μm) to about 14 mils (356 μm) and an uncoated porosity in the range of 55 to 70%, and,
the uncoated porosity is a percentage of volume of pores of the particulate filter relative to volume of the particulate filter.

### Claim 4 (depends on 1)

The emission treatment system of claim 1, wherein the catalyzed particulate filter has a coated porosity that is less than an uncoated porosity of the particulate filter.

### Claim 5 (depends on 4)

The emission treatment system of claim 4, wherein there is no layering of catalytic material on the surface of the walls of the particulate filter except optionally in areas of overlapped washcoat.

### Claim 6 (depends on 4)

The emission treatment system of claim 4, wherein the coated porosity is linearly proportional to a washcoat loading of the TWC catalytic material.

### Claim 7 (depends on 4)

The emission treatment system of claim 4, wherein the coated porosity is between 75 and 98% of the uncoated porosity.

### Claim 8 (depends on 7)

The emission treatment system of claim 7, wherein the coated porosity is between 80 and 95% of the uncoated porosity.

### Claim 9 (depends on 4)

The emission treatment system of claim 4, wherein a coated backpressure of the catalyzed particulate filter is non-detrimental to performance of the engine.

### Claim 10 (depends on 1)

The emission treatment system of claim 1, wherein the second TWC catalytic material has a d90 average particle diameter in the range of about 2.5 to about 8 μm.

### Claim 11 (depends on 1)

The emission treatment system of claim 1, wherein the second TWC catalytic material is formed from a single washcoat composition that permeates an inlet side, an outlet side, or both of the particulate filter.

### Claim 12 (depends on 1)

The emissions treatment system of claim 1, wherein a first single washcoat layer is present on the inlet side along up to about 0-100% of the axial length of the particulate filter from the upstream end and a second single washcoat layer is present on the outlet side along up to about 0-100% of the axial length of the particulate filter from the downstream end, wherein at least one of the first and single washcoat layers is present in an amount of >0%.

### Claim 13 (depends on 12)

The emissions treatment system of claim 12, wherein a first single washcoat layer is present on the inlet side along up to about 50-100% of the axial length of the particulate filter from the upstream end and a second single washcoat layer is present on the outlet side along up to about 50-100% of the axial length of the particulate filter from the downstream end.

### Claim 14 (depends on 13)

The emissions treatment system of claim 13, wherein the first single washcoat layer is present on the inlet side along up to about 50-55% of the axial length of the particulate filter from the upstream end and the second single washcoat layer is present on the outlet side along up to about 50-55% of the axial length of the particulate filter from the downstream end.

### Claim 15 (depends on 1)

The emissions treatment system of claim 1, wherein a single washcoat layer is present on the inlet side along up to about 100% of the axial length of the particulate filter from the upstream end and there is not a washcoat layer on the outlet side.

### Claim 16 (depends on 1)

The emissions treatment system of claim 1, wherein a single washcoat layer is present on the outlet side along up to about 100% of the axial length of the particulate filter from the downstream end and there is not a washcoat layer on the inlet side.

### Claim 17 (depends on 1)

The emission treatment system of claim 1, comprising the second TWC catalytic material in an amount of about 0.17 to about 5 g/in3 (about 10 to about 300 g/L).

### Claim 18 (depends on 1)

The emission treatment system of claim 1, wherein the second TWC catalytic material consists essentially of rhodium, ceria or a ceria composite, and alumina.

### Claim 19

A catalyzed particulate filter located in an emission treatment system downstream of a gasoline direct injection engine for treatment of an exhaust stream comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates and downstream of a three-way conversion (TWC) composite comprising a first TWC catalytic material on a flow-though substrate, the catalyzed particulate filter comprising:
a particulate filter having a wall thickness in the range of about 6 mils (152 μm) to about 14 mils (356 μm) and a porosity in the range of 55 to 70%; and
a second three-way conversion (TWC) catalytic material in an amount in the range of about 0.17 to about 5 g/in3 (10 to 300 g/L), the second TWC catalytic material comprising rhodium as the only platinum group metal
wherein the catalyzed particulate filter has a coated porosity that is less than an uncoated porosity of the particulate filter and a coated backpressure that is substantially the same as an uncoated backpressure of the particulate filter.

### Claim 20 (depends on 19)

The catalyzed particulate filter of claim 19, wherein:
the wall thickness is about 8 mils;
the amount of the second three-way conversion (TWC) catalytic material is about 0.17 to about 1.5 g/in3 (10 to 90 g/L), the second TWC catalytic material comprising rhodium as the only platinum group metal; and
the particulate filter has a mean pore size distribution of about 13 to about 25 μm.

### Claim 21 (depends on 1)

A method of treating an exhaust gas comprising hydrocarbons, carbon monoxide, nitrogen oxides, and particulates, the method comprising: situating the catalyzed particulate filter of claim 1 downstream of a gasoline direct injection engine and a three-way conversion (TWC) composite comprising a first TWC catalytic material on a flow-through substrate,
wherein upon operation of the engine, exhaust gas from the gasoline direct injection engine contacts the catalyzed particulate filter.

### Claim 22

A method of making emission treatment system for a gasoline direct injection engine, the method comprising:
positioning a three-way conversion (TWC) composite comprising a first TWC catalytic material on a flow-through substrate downstream of the gasoline direct injection engine; and
positioning the catalyzed particulate filter downstream of the TWC composite, wherein:
the obtaining a catalyzed particulate filter comprises a second three-way conversion (TWC) catalytic material permeating walls of a particulate filter, the particulate filter having a wall thickness of about 6 mils (152 μm) to about 14 mils (356 μm) and a porosity of 55 to 70%; and
the second TWC catalytic material comprises rhodium as the only platinum group metal.