Carbon Supported Catalyst Pore Structure Control

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Solution Overview

Problem

Catalyst durability and performance retention are significant challenges in automotive fuel cell technology due to platinum particle loss through dissolution, Ostwald ripening, and coalescence, as well as oxidation of the carbon support, which hinders reactant transport and electrode stability.

Innovation Solution

A method for forming a carbon-supported catalyst involves treating a platinum-group metal catalyst with an oxygen-containing gas at temperatures below 450°C, followed by molecular hydrogen exposure and acid leaching to create a catalyst with enhanced stability and pore structure, improving durability and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If high surface area carbon black with internal micropores is used as catalyst support, then catalyst surface area is improved, but micropores block reactant transport to Pt surface

Engineering Contradiction:

Improvecatalyst surface areaVSAvoidreactant transport

Core Design Contradiction:

Area of stationary objectVSEase of operation

Solution Approach 1:

The patent utilizes carbon black material inherently containing internal micropores (15 nm) as the catalyst support. The micropores are strategically employed to provide high surface area while the patent addresses the transport issue through catalyst design, where Pt particles are positioned to allow reactant access despite the micropore structure.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent embeds Pt particles within the carbon particle micropores structure. This nesting arrangement allows the Pt catalyst to be supported on high surface area carbon while the micropores provide both support structure and controlled access pathways for reactants to reach the embedded Pt particles.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If carbon support is oxidized to prevent Pt particle migration, then catalyst stability is improved, but electrode porosity collapses and reactant transport is hindered

Engineering Contradiction:

Improvecatalyst stabilityVSAvoidelectrode porosity

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent converts the harmful effect of carbon oxidation into a beneficial one by controlling the oxidation process to create a stable carbon support structure that prevents Pt particle migration and coalescence. The oxidation is managed to stabilize the carbon without causing excessive porosity collapse, thus transforming the potential harm into improved catalyst durability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent employs controlled oxidation at specific temperature conditions to change the physical and chemical parameters of the carbon support. This parameter control allows the carbon to become more stable and resistant to further degradation while maintaining sufficient porosity for reactant transport.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If Pt particles are embedded in carbon particle micropores to increase surface area, then catalyst loading is improved, but fuel cell performance loss increases due to limited reactant access

Engineering Contradiction:

ImprovePt surface areaVSAvoidfuel cell performance

Core Design Contradiction:

Area of stationary objectVSProductivity

Solution Approach 1:

The patent creates local variations in the catalyst structure where Pt particles are strategically positioned within the carbon micropores. This local arrangement ensures that while Pt surface area is maximized, the local environment around each Pt particle maintains adequate reactant access, preventing performance loss despite high loading.

Inventive Principle:

Principle #3Local quality

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 process results in improved catalyst stability and performance retention, maintaining high power output over cycles and reducing carbon support oxidation, thus addressing the challenges of platinum particle loss and electrode porosity collapse.

Implementation Method 1

The first carbon supported catalyst is contacted with an oxygen-containing gas at a temperature less than about 450° C. for a predetermined period of time to form a second carbon supported catalyst

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

The second carbon supported is subsequently contacted with molecular hydrogen to form a third carbon supported catalyst

Methodology Applied

Scientific EffectHydrogenation: Hydrogenation

Implementation Method 3

the first carbon supported catalyst or the second carbon supported catalyst is acid leached

Methodology Applied

Scientific EffectAcid leaching: Purification

Data Source

PatentUS9947935B1Facile control of pore structure in carbon-supported PGM-based catalysts

Publication Date: 2018.04.17 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A method for forming a carbon supported catalyst includes a step of providing a first carbon supported catalyst having a platinum-group metal supported on a first carbon support. Characteristically, the first carbon support has a first average micropore diameter and a first average carbon surface area. The first carbon supported catalyst is contacted with an oxygen-containing gas at a temperature less than about 450° C. for a predetermined period of time to form a second carbon supported catalyst, wherein the first carbon support or the second carbon supported catalyst is acid leached.