Pd-Pt Ceria-Zirconia Catalyst for Low-Temperature Methane Oxidation
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Solution Overview
Problem
Existing hydrocarbon decomposition catalysts exhibit low methane decomposition ability at relatively low temperatures, which is a challenge in treating exhaust gases from internal combustion engines using natural gas due to methane's chemical stability and low emission temperatures.
Innovation Solution
A methane oxidation catalyst comprising a ceria-zirconia composite oxide support with specific ceria and zirconia content ratios and an active metal mixture of Pd and Pt, produced through a slurry preparation and calcination process, enables high methane decomposition at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrocarbon decomposition catalyst with rare earth oxide support is used, then high activity and long-term stability at high temperature are improved, but methane decomposition ability at relatively low temperature deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst support by incorporating a specific ratio of ceria (5-15 mass%) and zirconia (85-95 mass%) to optimize both low-temperature methane decomposition activity and high-temperature stability. This compositional adjustment resolves the contradiction between activity at different temperatures.
Solution Approach 2:
The patent creates a composite oxide material combining ceria and zirconia in specific proportions, leveraging the complementary properties of both oxides: ceria provides oxygen storage capacity and catalytic activity, while zirconia provides structural stability. This composite approach simultaneously improves low-temperature methane decomposition and maintains high-temperature reliability.
2Temperature
If methane oxidation catalyst is required for low temperature exhaust gas treatment, then methane decomposition ability at low temperature is improved, but the chemical stability challenge of methane remains
Solution Approach 1:
The patent modifies the catalyst's chemical composition by incorporating Pd and Pt active metals in optimized ratios, which lowers the oxidation temperature threshold for methane decomposition. This compositional change enables the catalyst to overcome methane's inherent chemical stability at temperatures below 450°C.
Solution Approach 2:
The patent employs Pd and Pt as active metals that facilitate accelerated oxidation of methane at lower temperatures. These precious metals act as strong oxidizing catalysts, enabling methane decomposition at temperatures (≤450°C) that would otherwise be insufficient to overcome methane's chemical stability.
3Productivity
If exhaust gas from natural gas engines is treated, then hydrocarbon decomposition is improved, but unburned methane removal remains insufficient due to low emission temperature
Solution Approach 1:
The patent applies different functional components to different aspects of the catalytic process: the ceria-zirconia support provides structural stability and oxygen storage, while Pd and Pt active metals provide the specific activity for methane oxidation. This functional differentiation enables simultaneous handling of general hydrocarbons and resistant methane at low temperatures.
Solution Approach 2:
The patent creates a composite catalyst system combining ceria-zirconia support with Pd-Pt active metals, where each component contributes specific properties. This composite structure enables the catalyst to maintain high hydrocarbon decomposition efficiency while simultaneously achieving effective unburned methane removal at low exhaust temperatures.
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 efficient methane oxidation at temperatures up to 450°C, effectively decomposing methane into CO2 and H2O, with improved activity and cost-effectiveness.
Implementation Method 1
a catalyst support containing a ceria-zirconia composite oxide; a content ratio of ceria in the catalyst support is 5% by mass or more and less than 15% by mass
Implementation Method 2
an active metal supported on the catalyst support and containing Pd and Pt; a content ratio of the Pd in the active metal is 50% by mass or more
Implementation Method 3
a third step of calcining the powder at 400° C or more and 600°C or less to obtain a methane oxidation catalyst
Data Source
Figure 1~2
AI summary
A methane oxidation catalyst is a catalyst for oxidizing methane, and contains a catalyst support containing a ceria-zirconia composite oxide, and an active metal supported on the catalyst support and containing Pd and Pt. Furthermore, the content ratio of ceria in the catalyst support is 5% by mass or more and less than 15% by mass.