Palladium Fixing via Tannic Acid Complex for Stable Oxygen Storage

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Solution Overview

Problem

Conventional three-way catalysts (TWCs) face limitations in controlling PGM particle size and metal-support interactions, leading to reduced emissions abatement efficiency, higher PGM costs, and unstable oxygen storage capacity due to sintering and migration of palladium during high-temperature calcination and aging processes.

Innovation Solution

A method involving a complex of polyphenol with an ester functional group and palladium is applied to a support material, which is then heated to form nanoparticles, enhancing PGM anchoring and distribution, resulting in improved catalytic activity and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional inorganic PGM precursor solutions are used for washcoat impregnation, then the catalyst can be manufactured with standard procedures, but the PGM particle size and metal-support interactions cannot be effectively controlled, leading to metal migration and grain growth during high temperature calcination

Engineering Contradiction:

ImprovePGM particle size controlVSAvoidcalcination process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

A polymer intermediary is introduced between the PGM precursor and the support material. The polymer forms a complex with the PGM precursor, enabling controlled deposition onto the support. During calcination, the polymer decomposes to leave behind uniformly distributed PGM nanoparticles with controlled size, preventing metal migration and grain growth while maintaining process simplicity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical state and molecular weight parameters of the polymer used as intermediary. By selecting specific polymers with appropriate molecular weights and functional groups, the PGM precursor forms stable complexes that decompose at controlled rates during calcination, achieving precise particle size control without requiring complex multi-step processes

Inventive Principle:

Principle #35Parameter changes

2Reliability

If high PGM loading is used to maintain catalytic activity, then emissions abatement efficiency can be maintained, but the cost increases significantly

Engineering Contradiction:

Improveemissions abatement efficiencyVSAvoidPGM loading

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The polymer intermediary enables local optimization of PGM distribution on the support material surface. PGM nanoparticles are uniformly dispersed at optimal locations with controlled density, maximizing catalytic activity per unit mass of PGM. This localized quality control allows reduced overall PGM loading while maintaining high emissions abatement efficiency

Inventive Principle:

Principle #3Local quality

3Stability of the object's composition

If high temperature calcination is performed to fix PGM onto support, then the catalyst structure is formed, but metal migration and grain growth occur, reducing OSC stability during aging

Engineering Contradiction:

ImproveOSC stabilityVSAvoidcalcination temperature

Core Design Contradiction:

Stability of the object's compositionVSTemperature

Solution Approach 1:

The polymer intermediary performs preliminary anchoring of the PGM precursor to the support material before calcination. This preliminary action creates strong metal-support interactions that prevent metal migration during the subsequent high temperature calcination process. The controlled decomposition of the polymer framework also prevents grain growth, maintaining small particle size and stable OSC throughout the catalyst's lifetime

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The polymer matrix provides a protective cushioning effect during calcination, physically constraining the PGM precursors and preventing excessive aggregation. This beforehand cushioning protects against the harmful effects of high temperature, allowing the necessary thermal treatment to form the catalyst structure while preventing metal migration and maintaining OSC stability

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 method produces catalyst articles with superior light-off performance, reduced PGM loading requirements, and stable oxygen storage capacity throughout the catalyst's lifetime, maintaining high catalytic activity after aging.

Implementation Method 1

heating the loaded support material to form nanoparticles of the PGM on the support material

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 2

heating the loaded support material to form nanoparticles of the PGM on the support material

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS11845065B2Palladium fixing and low fresh oxygen storage capacity using tannic acid as a complexing and reducing agent

Publication Date: 2023.12.19 JOHNSON MATTHEY PLC

AI summary

A method of manufacturing a catalyst article, the method comprising: providing a complex of a polyphenol and a PGM, the polyphenol comprising an ester functional group, the PGM comprising palladium; providing a support material; applying the complex to the support material to form a loaded support material; disposing the loaded support material on a substrate; and heating the loaded support material to form nanoparticles of the PGM on the support material.