Silica-Doped Methane Oxidation Catalyst for Water and Sulfur Tolerance
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Solution Overview
Problem
Existing catalysts for reducing methane slip in lean burn natural gas engines are not commercially satisfactory due to rapid deactivation by water and sulfur, lack of thermal stability, and reduced engine efficiency, necessitating new catalysts and methods to effectively remove methane from gas streams.
Innovation Solution
A methane oxidation catalyst comprising a support of alumina doped with silica, with platinum and palladium as active phases, designed to withstand gaseous water and sulfur, achieving enhanced thermal stability and efficiency in methane conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional catalysts are used to reduce methane slip, then methane oxidation can occur, but the catalysts are rapidly deactivated by water and sulfur
Solution Approach 1:
The patent uses a composite catalyst structure combining platinum and palladium metals supported on alumina with silica doping. This composite material approach creates a catalyst that leverages the complementary properties of different components: platinum provides high methane oxidation activity while palladium contributes sulfur tolerance, and the alumina-silica support structure provides thermal stability and resistance to water deactivation. The synergistic interaction between these components resolves the contradiction by achieving both high productivity and reliability.
Solution Approach 2:
The patent modifies the catalyst composition parameters by introducing silica doping into the alumina support structure and optimizing the platinum-to-palladium metal ratio. These parameter changes transform the catalyst properties to resist deactivation by water and sulfur while maintaining high methane conversion efficiency. The specific compositional parameters are tuned to achieve both durability and productivity.
2Object-generated harmful factors
If engine calibration is adjusted to reduce methane slip, then methane emissions decrease, but engine performance and efficiency are reduced
Solution Approach 1:
The catalyst acts as an intermediary device that processes the exhaust gas stream after the engine combustion process. Instead of modifying engine calibration to reduce methane slip, the catalyst provides a separate treatment stage that converts unburned methane into carbon dioxide and water. This intermediary approach allows the engine to operate at optimal efficiency while the catalyst handles the methane emission problem in the exhaust stream.
Solution Approach 2:
The patent replaces the mechanical approach of engine calibration adjustment with a chemical solution using catalytic oxidation. Rather than mechanically adjusting combustion parameters to reduce methane slip, the system uses chemical catalysis to convert methane emissions after they are generated, achieving the same emission reduction goal without compromising engine performance.
3Productivity
If catalysts are designed for high methane oxidation activity, then methane conversion improves, but thermal and hydrothermal stability are reduced
Solution Approach 1:
The patent employs a composite material system where platinum and palladium metals are supported on a thermally stable alumina-silica composite structure. The alumina provides exceptional thermal stability and resistance to sintering at high temperatures, while silica doping enhances the hydrothermal stability and prevents phase transitions. This composite structure allows the catalyst to maintain high methane conversion activity while withstanding thermal and hydrothermal aging conditions.
Solution Approach 2:
The patent optimizes the physical and chemical parameters of the support material, including the alumina-silica ratio, pore structure, and surface area, to achieve optimal balance between catalytic activity and thermal stability. These parameter changes ensure that the catalyst maintains its structural integrity and compositional stability under thermal and hydrothermal conditions while preserving high methane oxidation 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 effectively reduces methane content in exhaust streams by at least 50% at temperatures below 500°C, demonstrating high stability and resistance to deactivation, thereby reducing greenhouse gas emissions.
Implementation Method 1
a methane oxidation catalyst... to remove methane from a gas stream
Implementation Method 2
a methane oxidation catalyst... with platinum and palladium as active phases
Data Source
AI summary
Provided herein are methane oxidation catalysts and methods of using said methane oxidation catalysts to reduce methane in a gas stream comprising methane and sulfur. Select methods of the present disclosure comprise contacting the gas stream with a methane oxidation catalyst comprising a support comprising alumina doped with silica, with platinum and palladium as active phases. The platinum and the palladium may comprise from about 1 wt % to about 10 wt % of the methane oxidation catalyst. The methane oxidation catalysts, methods and uses of the same may, in selected embodiments, exhibit improvements in resistance to sulfur poisoning over the prior art.