Catalyst System for Ammonia Oxidation with Alloy Gradient
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Solution Overview
Problem
Catalyst systems for flow reactors face challenges in minimizing precious metal usage while maintaining catalytic efficiency, as existing systems often require high platinum content and suffer from precious metal loss due to oxidation and sublimation, leading to increased costs and maintenance needs.
Innovation Solution
A catalyst system comprising at least three catalyst network groups with specific noble metal wire compositions, where the first group has a high platinum alloy, the second group uses a palladium alloy with varying metals, and the third group also uses a palladium alloy, with the rhodium content decreasing and palladium content increasing in the direction of flow, optimizing precious metal usage and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high platinum content is used in catalyst meshes, then catalytic efficiency is maintained, but precious metal cost and investment increase
Solution Approach 1:
The patent applies local quality by using different metal compositions in different zones of the catalyst system. The front catalyst meshes use platinum-based alloys for high catalytic activity where fresh reactants enter, while rear catalyst meshes use palladium-based alloys where the reaction is already progressing. This spatial differentiation of material properties optimizes both catalytic efficiency and precious metal usage.
Solution Approach 2:
The catalyst system is segmented into multiple catalyst meshes with different compositions arranged in sequence. Instead of using uniform high-platinum catalysts throughout, the system divides the catalytic function across multiple stages with decreasing platinum content from front to rear, reducing overall platinum consumption while maintaining effectiveness.
2Duration of action of stationary object
If platinum-rhodium alloy is used to maintain service life, then catalyst durability is improved, but precious metal loss due to oxidation and sublimation increases
Solution Approach 1:
The patent replaces expensive platinum-rhodium alloys with more economical palladium-based alloys in the rear catalyst meshes where the harshest oxidation conditions have already been endured in the front meshes. This substitution reduces precious metal content and potential loss while maintaining adequate service life for the overall system.
3Quantity of substance
If multiple catalyst meshes with different compositions are used, then precious metal efficiency is optimized, but system complexity increases
Solution Approach 1:
The patent optimizes precious metal usage by systematically varying the metal composition parameters across the catalyst meshes. Platinum content decreases while palladium content increases from front to rear meshes, creating a gradient that balances catalytic activity with cost efficiency. This controlled parameter change achieves optimization without excessive complexity.
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
This configuration significantly enhances catalytic efficiency while reducing the overall platinum content, leading to improved system performance and extended service life with reduced precious metal loss.
Implementation Method 1
a catalyst system for a flow reactor, comprising at least three catalyst mesh groups arranged one behind the other in the flow direction, each catalyst mesh group being formed from at least one catalyst mesh each comprising at least one precious metal wire
Implementation Method 2
the catalytic combustion of ammonia, in which a fresh gas containing at least ammonia is passed through a catalyst system
Implementation Method 3
During operation, the catalyst gauzes continuously lose precious metal due to oxidation and sublimation
Implementation Method 4
During operation, the catalyst gauzes continuously lose precious metal due to oxidation and sublimation
Data Source
Figure 1
AI summary
The present invention relates to a catalyst system for flow reactors, characterized by the sequence of precious metal alloys used in the catalyst networks forming the catalyst system. By using palladium alloys for a second and third catalyst network group, the overall platinum content of the catalyst system can be kept relatively low. The invention also relates to a process for the catalytic combustion of ammonia, in which a fresh gas containing at least ammonia is passed through a catalyst system.