Palladium Catalyst on Alumina-Zirconia for Methane Oxidation
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Solution Overview
Problem
Current methane combustion catalysts face issues with expense, physical/chemical complexity, lack of high activity at low temperatures, instability at high temperatures, and deactivation by water in exhaust streams.
Innovation Solution
A nanoparticulate palladium-based catalyst supported on non-hierarchical ceria and alumina, prepared by solution combustion synthesis, which exhibits light-off at approximately 200°C, maintains stability up to 800°C, and retains activity in exhaust streams with up to 15% water, featuring a solid solution of palladium and ceria on an alumina support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Pd-based catalysts are supported on alumina or zirconia for low temperature activity, then catalytic activity at low temperatures is improved, but catalyst stability at high temperatures deteriorates due to sintering and phase transition
Solution Approach 1:
The patent employs a composite support structure combining alumina and zirconia in specific ratios (Al2O3: 30-70 wt%, ZrO2: 30-70 wt%). This composite approach leverages the low-temperature activity promotion of alumina/zirconia while using the other component to suppress sintering and phase transitions at high temperatures, thus resolving the contradiction between low-temperature activity and high-temperature stability
2Reliability
If ultra-stable Pd-based catalysts are prepared by reaction with rare-earth oxides for high temperature stability, then catalyst stability at high temperatures is improved, but catalytic activity at low temperatures deteriorates
Solution Approach 1:
The patent uses a composite of alumina and zirconia rather than rare-earth oxides. The specific composition ratio and nanoparticulate structure of this composite provide high-temperature stability through resistance to sintering and phase transitions, while simultaneously maintaining low-temperature activity, thus resolving the contradiction without the low-temperature activity penalty associated with rare-earth oxide stabilization
3Productivity
If core-shell Pd@CeO2 catalysts are prepared to enhance Pd-support interface, then catalytic activity is improved, but preparation complexity and cost increase
Solution Approach 1:
The patent combines Pd nanoparticles with a composite alumina-zirconia support in a single catalyst structure, achieving enhanced Pd-support interface interaction and high catalytic activity. This merged structure simplifies the preparation process compared to separate core-shell formation steps, reducing both preparation complexity and cost while maintaining high activity
4Productivity
If flaring is used to remove methane from exhaust streams, then methane removal is achieved, but environmental harm increases due to incomplete combustion and black carbon production
Solution Approach 1:
The patent utilizes the catalyst to lower the reaction temperature for complete methane combustion from typical flaring temperatures to below 400°C. The nanoparticulate Pd on alumina-zirconia support provides high activity at these reduced temperatures, enabling complete combustion that eliminates black carbon formation while maintaining efficient methane removal, thus resolving the contradiction between removal efficiency and environmental harm
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 achieves superior low-temperature performance, maintains high activity across a wide temperature range, and remains effective in the presence of water, demonstrating enhanced stability and catalytic efficiency.
Implementation Method 1
solution combustion synthesis
Implementation Method 2
solution combustion synthesis
Implementation Method 3
Pd-based catalysts have been found to exhibit the highest level of catalytic activity
Implementation Method 4
oxidation of methane
Implementation Method 5
adsorption of water on the support was observed to suppress reaction rate
Data Source
AI summary
This invention relates to a novel palladium catalyst for the substantially complete oxidative removal of methane from exhaust streams at low operating temperatures compared to other current palladium catalysts and to methods of preparing the catalyst. Use of the catalyst to remove methane from vehicle exhaust streams, crude oil production and processing exhaust streams, petroleum refining exhaust streams and natural gas production and processing exhaust streams.