PtRh Anode Catalyst Layer for CO Tolerant Fuel Cells
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Solution Overview
Problem
Proton exchange membrane fuel cells face performance losses due to carbon monoxide poisoning, especially in automotive applications where tight CO specifications are challenging to meet, and existing solutions like air bleeding or high-temperature operation come with drawbacks such as reduced fuel efficiency and material instability.
Innovation Solution
An anode catalyst layer using a binary alloy of PtX, where X is rhodium or osmium, with a platinum atomic percentage between 45 to 80 and X between 20 to 55 atomic percent, dispersed on a support material, allowing operation with up to 5 ppm carbon monoxide in the hydrogen stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If air bleeding is used to remove carbon monoxide, then carbon monoxide poisoning is reduced, but fuel efficiency decreases
Solution Approach 1:
The patent extracts and removes carbon monoxide from the hydrogen fuel stream using a dedicated CO removal layer containing metal oxide particles before the fuel reaches the catalyst layer, eliminating the need for air bleeding and preserving fuel efficiency
Solution Approach 2:
The patent introduces an intermediary CO removal layer containing metal oxide particles that acts as a mediator between the fuel stream and the catalyst layer, selectively removing CO without requiring air injection and thus avoiding the energy loss associated with air bleeding
2Object-affected harmful factors
If high temperature operation is used to tolerate carbon monoxide, then carbon monoxide tolerance is improved, but material stability deteriorates
Solution Approach 1:
The patent changes the chemical state of metal oxide particles from reduced to oxidized form, creating an active species that selectively binds and removes CO at low temperatures, thereby achieving CO tolerance without high temperature operation and preserving material stability
Solution Approach 2:
The patent uses a composite structure combining metal oxide particles with specific surface area and composition on a support material, creating a multifunctional layer that provides CO removal capability at low temperatures while maintaining overall system stability
3Reliability
If tight carbon monoxide specifications are enforced, then fuel cell performance is protected, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary CO removal in a dedicated layer before the fuel reaches the catalyst layer, ensuring that CO specifications are met without requiring complex control systems or post-processing, thereby simplifying manufacturing while protecting fuel cell performance
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 catalyst layer maintains fuel cell performance with reduced carbon monoxide poisoning effects, as evidenced by lower anode overpotentials and voltage requirements, even at higher CO concentrations, thus addressing the limitations of current CO tolerance in PEMFCs.
Implementation Method 1
carbon monoxide binds strongly to platinum sites, resulting in the reduction of surface active sites available for hydrogen adsorption and oxidation
Implementation Method 2
the anode catalyst oxidises carbon monoxide to carbon dioxide in the presence of hydrogen
Implementation Method 3
a fuel, which is typically hydrogen or an alcohol, such as methanol or ethanol, is oxidised at a fuel electrode (anode) and oxygen, typically from air, is reduced at an oxygen electrode (cathode) to produce an electric current
Data Source
AI summary
A method of operating a fuel cell having an anode, a cathode and a polymer electrolyte membrane disposed between the anode and the cathode, includes feeding the anode with an impure hydrogen stream having low levels of carbon monoxide up to 5 ppm, and wherein the anode includes an anode catalyst layer including a carbon monoxide tolerant catalyst material, wherein the catalyst material includes: (i) a binary alloy of PtX, wherein X is a metal selected from the group consisting of rhodium and osmium, and wherein the atomic percentage of platinum in the alloy is from 45 to 80 atomic % and the atomic percentage of X in the alloy is from 20 to 55 atomic %; and (ii) a support material on which the PtX alloy is dispersed; wherein the total loading of platinum group metals (PGM) in the anode catalyst layer is from 0.01 to 0.2 mgPGM/cm2.