Heatable Ammonia Slip Catalyst for N2O Suppression
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Solution Overview
Problem
Conventional ammonia slip catalysts (ASC) have insufficient selectivity for ammonia oxidation to nitrogen, leading to unwanted nitrogen oxide (NOx) and nitrogen oxide (N2O) formation, which are harmful and counterproductive for reducing nitrogen oxides in exhaust gases.
Innovation Solution
An electrically heatable catalyst system comprising a support substrate with platinum on metal oxide and SCR-active zeolite composition, where the catalyst can be maintained within a temperature window of 300°C to 450°C to optimize ammonia conversion and minimize N2O formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional ammonia slip catalysts are used for ammonia oxidation, then ammonia conversion is achieved, but unwanted nitrogen oxide (NOx) and nitrogen oxide (N2O) formation occurs
Solution Approach 1:
The patent applies parameter changes by precisely controlling the operating temperature within the 300-450°C window and optimizing the platinum particle size (50-200 nm) and support material composition (alumina, titania, ceria, zirconia) to achieve high ammonia conversion while suppressing unwanted NOx and N2O formation through modified reaction kinetics
Solution Approach 2:
The patent uses composite materials by combining platinum with specific metal oxide supports (alumina, titania, ceria, zirconia) to create a catalyst system that leverages the synergistic effects of these materials, where the support materials help control selectivity and reduce harmful by-product formation while maintaining high ammonia conversion activity
2Productivity
If the catalyst temperature is increased to improve ammonia conversion, then reaction rate increases, but N2O formation increases
Solution Approach 1:
The patent resolves this contradiction by identifying and maintaining the optimal temperature parameter within the 300-450°C range, where the reaction kinetics favor high ammonia conversion while suppressing the competing N2O formation pathway, thus achieving both high productivity and low harmful emissions simultaneously
3Productivity
If platinum particle size is decreased to increase surface area, then catalytic activity increases, but selectivity control becomes more difficult
Solution Approach 1:
The patent optimizes the platinum particle size parameter to the specific range of 50-200 nm, where the surface area is sufficiently high to provide high catalytic activity while the particle size remains large enough to maintain controllable selectivity and prevent excessive formation of unwanted by-products
Solution Approach 2:
The patent combines platinum with specific metal oxide supports to create a composite catalyst system where the support materials play a crucial role in controlling selectivity and stabilizing the platinum particles, thereby maintaining both high activity and good selectivity control
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 system achieves high ammonia conversion with reduced N2O formation, ensuring efficient nitrogen oxide reduction while avoiding harmful by-products.
Implementation Method 1
a catalyst comprising a support substrate, material a containing platinum on metal oxide and material b containing a composition active for the SCR reaction
Implementation Method 2
material b containing a composition active for the SCR reaction
Implementation Method 3
the catalyst is heatable
Data Source
Figure 1~2
AI summary
Catalyst comprising - a support substrate of length L extending between an end X and an end Y - material a containing platinum on a metal oxide and - material b containing a composition active for the SCR reaction and no precious metal wherein material a and material b are different and the catalyst is heatable.