Germanium Molecular Sieve Catalyst for Methane Oxidation Durability
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Solution Overview
Problem
Natural gas engines emit significant methane emissions due to the low reactivity of methane, which is exacerbated by catalyst deactivation from sulfur, water, and thermal aging, leading to high costs and inefficiencies in existing palladium-based catalyst systems.
Innovation Solution
A catalytic material comprising a molecular sieve with a framework of silicon, oxygen, and germanium, supported by platinum group metals, particularly palladium, with a germanium content of 15 to 20 mol%, enhances methane oxidation activity and durability under hydrothermal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pgm loadings are used to improve methane conversion, then methane oxidation activity is improved, but catalyst cost increases
Solution Approach 1:
The patent changes the chemical composition parameters of the molecular sieve framework by incorporating germanium at 15-20 mol%, which fundamentally alters the catalyst's interaction with methane and water. This compositional parameter change enables high methane conversion activity while reducing the required pgm loading, thereby resolving the contradiction between productivity and quantity of substance (cost).
Solution Approach 2:
The patent creates a composite catalytic system combining platinum group metals with a germanium-containing molecular sieve framework. This composite material synergistically enhances methane oxidation activity through the interaction between the PGM active sites and the germanium-modified framework, achieving high conversion efficiency with reduced PGM loadings and thus lower costs.
2Productivity
If conventional Pd-based catalysts are used for methane oxidation, then methane conversion is achieved, but catalyst deactivation occurs due to sulfur, water, and thermal aging
Solution Approach 1:
The patent converts the harmful effect of water vapor, which traditionally causes Pd catalyst deactivation, into a beneficial feature. The germanium-containing molecular sieve framework specifically resists water-induced deactivation and may even utilize water vapor to maintain or enhance catalytic activity through hydrothermal stabilization, thereby improving reliability while maintaining productivity.
Solution Approach 2:
The patent modifies the thermal and chemical stability parameters of the catalyst support framework by incorporating germanium into the molecular sieve structure. This parameter change increases the framework's resistance to thermal aging and sulfur poisoning, preventing catalyst deactivation and thereby improving reliability without compromising methane conversion productivity.
3Productivity
If high pgm loadings are used to achieve high methane conversion, then emission regulations are met, but hydrothermal durability decreases
Solution Approach 1:
The patent develops a composite catalyst system where platinum group metals are supported on a germanium-containing molecular sieve framework. This composite structure provides both high methane conversion activity (through PGM sites) and exceptional hydrothermal durability (through the germanium-stabilized framework), resolving the contradiction between productivity and duration of action.
Solution Approach 2:
The patent changes the chemical composition parameter of the support framework by incorporating 15-20 mol% germanium, which fundamentally improves hydrothermal stability. This parameter change allows the catalyst to maintain high methane conversion activity over extended periods under hydrothermal conditions, thereby increasing the duration of action without sacrificing productivity.
4Productivity
If Pd-based catalysts are used under lean burn conditions, then methane oxidation is achieved, but water inhibition causes activity loss
Solution Approach 1:
The patent converts the harmful water inhibition effect into a beneficial feature by using a germanium-containing molecular sieve framework that is inherently resistant to water poisoning. The germanium framework may even utilize water vapor to maintain structural integrity and catalytic activity, thereby eliminating the harmful effect while preserving methane oxidation productivity under lean burn conditions.
Solution Approach 2:
The patent changes the chemical composition parameter of the catalyst framework by incorporating germanium, which fundamentally alters the catalyst's interaction with water vapor. This parameter change reduces the strength of water adsorption sites and prevents water-induced deactivation, thereby maintaining high methane oxidation activity despite the presence of water inhibition factors.
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 catalytic material achieves high methane conversion efficiency at low temperatures with improved thermal and hydrothermal stability, reducing catalyst deactivation and maintaining oxidative activity in the presence of water vapor.
Implementation Method 1
a catalytic material for treating an exhaust gas produced by a natural gas engine, which catalytic material comprises a molecular sieve and a platinum group metal (PGM) supported on the molecular sieve
Implementation Method 2
Palladium-based catalysts are well known as the most active type of catalyst for methane oxidation under both conditions
Implementation Method 3
methane oxidation activity
Implementation Method 4
the germanium is present in an amount of from 15 to 20 mol %. The catalytic material achieves high methane conversion efficiency at low temperatures with improved thermal and hydrothermal stability, reducing catalyst deactivation and maintaining oxidative activity in the presence of water vapor
Data Source
AI summary
The present invention relates to a catalytic material for treating an exhaust gas produced by a natural gas engine, which catalytic material comprises a molecular sieve and a platinum group metal (PGM) supported on the molecular sieve, wherein the molecular sieve has a framework comprising silicon, oxygen and germanium, and has a content of heteroatom T-atoms of ≤about 0.20 mol %, wherein the germanium is present in an amount of from 15 to 20 mol %. The present invention further relates to a catalyst article and a compressed natural gas combustion and exhaust system.