Three-Way Catalyst OSC Material SSA Control for Thermal Durability

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Solution Overview

Problem

Current three-way catalysts (TWCs) for gasoline engines face challenges in improving performance during cold start stages and maintaining emission control effectiveness due to variations in specific surface area (SSA) of oxygen storage capacity (OSC) materials upon aging, which affects thermal durability and emission control performance.

Innovation Solution

A catalytic composition comprising a platinum group metal (PGM) component and an oxygen storage capacity (OSC) material with a fresh specific surface area of at least 10 m2/g and a minimal SSA difference of no more than 30 m2/g between fresh and aged OSC materials, enhancing thermal durability and emission control performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional TWC materials are used, then manufacturing cost is reduced, but thermal durability and emission control performance deteriorate due to large SSA variation upon aging

Engineering Contradiction:

Improvethermal durabilityVSAvoidmaterial selection complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by specifying precise SSA ranges for OSC materials (fresh SSA: 10-100 m2/g, aged SSA: 70-130 m2/g) and limiting the SSA difference to 30-100 m2/g. These quantitative parameter constraints transform the material selection from a complex qualitative process into a defined parameter optimization problem, improving thermal durability while maintaining manufacturability through clear specification criteria.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by combining OSC materials with specific SSA characteristics with PGM components and washcoat materials (alumina, silica, magnesia). This composite approach creates a synergistic catalyst system where the OSC material's controlled SSA variation upon aging enhances overall thermal durability and emission control performance beyond what individual materials could achieve alone.

Inventive Principle:

Principle #40Composite materials

2Productivity

If OSC material with high fresh SSA is used, then catalytic activity is improved, but SSA loss upon aging increases reducing performance

Engineering Contradiction:

Improvecatalytic activityVSAvoidSSA stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies beforehand cushioning by pre-selecting OSC materials with specific SSA characteristics before aging occurs. The material is chosen to have a fresh SSA within 10-100 m2/g that will maintain sufficient surface area (70-130 m2/g) after aging, cushioning against the expected SSA loss and ensuring continued catalytic activity and thermal durability throughout the catalyst's service life.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If TWC performance is improved for cold start and light-off, then emission control is enhanced, but material cost increases

Engineering Contradiction:

Improveemission control performanceVSAvoidPGM loading

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by optimizing the SSA parameters of the OSC material to enhance catalytic activity and thermal durability. This parameter optimization improves emission control performance during cold start and light-off conditions by maximizing the utilization of PGM components, thereby achieving better performance without necessarily increasing PGM loading quantities.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution improves catalytic properties, particularly in NOx emission control, and reduces costs by maintaining excellent performance under various emission control tests, including cold start conditions and light-off tests, compared to conventional TWCs.

Implementation Method 1

an oxygen storage capacity (OSC) material, wherein the OSC material has a fresh specific surface area (SSA) of at least 10 m2/g

Methodology Applied

Scientific EffectOxygen storage capacity: Absorption (physical)

Implementation Method 2

TWCs perform three main functions: (1) oxidation of CO; (2) oxidation of unburnt HCs

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 3

(3) reduction of NOx

Methodology Applied

Scientific EffectReduction: Reduction

Data Source

PatentUS11614013B2Twc catalysts for gasoline engine exhaust gas treatments

Publication Date: 2023.03.28 JOHNSON MATTHEY PLC

AI summary

A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprising: a substrate comprising an inlet end and an outlet end with an axial length L; a first catalytic region comprising a first platinum group metal (PGM) component and a first oxygen storage capacity (OSC) material, wherein the first OSC material has a fresh specific surface area (SSA) of at least 10 m2/g; and wherein the first OSC material has an SSA difference of no more than 30 m2/g between the fresh first OSC material and the aged first OSC material.