Platinum-Tantalum Alloy Catalyst for CO Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Platinum catalysts in phosphoric acid fuel cells are susceptible to poisoning by carbon monoxide, even at low levels, leading to reduced efficiency and the need for complex and costly carbon monoxide reduction processes.
Innovation Solution
A binary alloy catalyst comprising platinum-tantalum with tantalum present at 15 to 50 atomic% is developed, which can be used as an unsupported or supported catalyst in fuel cells, providing improved tolerance to carbon monoxide and maintaining performance with fuel streams containing up to 4% CO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pure platinum catalyst is used, then catalytic activity for fuel oxidation is high, but carbon monoxide tolerance is poor leading to catalyst poisoning
Solution Approach 1:
The patent applies composite materials by creating a platinum-tantalum alloy catalyst where tantalum atoms are incorporated into the platinum lattice. This composite structure at the atomic level modifies the electronic and geometric properties of platinum, enabling it to tolerate carbon monoxide while maintaining catalytic activity for fuel oxidation.
Solution Approach 2:
The patent changes the compositional parameter of the catalyst by introducing tantalum at specific concentrations (5-50 atomic%). This parameter change transforms the catalyst's interaction with carbon monoxide, shifting from strong binding (poisoning) to tolerant behavior, while preserving the necessary catalytic function.
2Reliability
If tantalum content is increased above 8 atomic%, then carbon monoxide tolerance improves, but fuel reaction sites are blocked reducing catalytic activity
Solution Approach 1:
The patent optimizes the tantalum concentration parameter within a specific range (5-50 atomic%, preferably 10-30 atomic%). This parameter optimization achieves the right balance where sufficient tantalum is present to provide carbon monoxide tolerance through electronic modification, while maintaining enough platinum surface sites for fuel oxidation activity.
Solution Approach 2:
The patent creates local quality variations in the catalyst structure where tantalum atoms are distributed throughout the platinum lattice, creating regions with modified electronic properties that tolerate CO, while maintaining overall catalytic functionality for fuel oxidation.
3Productivity
If tantalum content is decreased below 2 atomic%, then fuel reaction sites remain available, but carbon monoxide tolerance decreases to unacceptable levels
Solution Approach 1:
The patent establishes a minimum tantalum concentration threshold (5-50 atomic%, preferably 10-30 atomic%) below which carbon monoxide tolerance becomes unacceptable. This parameter threshold ensures sufficient electronic modification of platinum to prevent CO poisoning while maintaining catalytic activity.
4Object-affected harmful factors
If extensive carbon monoxide reduction processes are implemented, then catalyst poisoning is avoided, but system size, complexity and cost increase to prohibitive levels
Solution Approach 1:
The patent converts the harmful effect of carbon monoxide into a beneficial situation by developing a catalyst that actively tolerates and operates efficiently in the presence of CO. This eliminates the need for complex CO reduction systems, as the catalyst itself becomes the solution to the poisoning problem.
Solution Approach 2:
The patent extracts the carbon monoxide removal function from the fuel processing system by incorporating CO tolerance directly into the catalyst material. This eliminates the need for separate CO reduction equipment, simplifying the overall system architecture.
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 platinum-tantalum catalyst demonstrates enhanced performance and increased carbon monoxide tolerance, achieving a 10mV improvement in fuel cell output and higher electrical efficiency compared to traditional platinum catalysts, while reducing system complexity and cost.
Implementation Method 1
Platinum, and in particular platinum, have been found to be the most efficient and stable electrocatalyst for fuel cells operating at temperatures below 300°C
Implementation Method 2
an acid electrolyte wherein proton conduction is carried out by materials such as phosphoric acid and/or polyphosphonic acid
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
Figure 1
AI summary
A binary alloy catalyst comprising platinum and tantalum, wherein the tantalum is present in the alloy at 15 to 50 atomic% and a phosphoric acid fuel cell comprising such a catalyst is disclosed. The catalyst provides a better CO tolerance.