Twisted Pt-Pd Catalyst Wire for Ammonia Oxidation
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Solution Overview
Problem
Catalyst gauzes made from Pd-based wires are mechanically weak, leading to increased N2O production during ammonia oxidation, as they can develop breaks and have a limited technical life, making them unsuitable for sustained use in reducing N2O levels effectively.
Innovation Solution
A twisted wire made from an assembly of intertwined filaments, each comprising at least 50% by weight of Pt, twisted together to increase the contact surface area and density, enhancing catalytic activity and NO selectivity while reducing N2O production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If Pd-based wire is used to manufacture catalyst gauze for N2O reduction, then N2O decomposition capability is improved, but mechanical strength deteriorates causing breaks during use
Solution Approach 1:
The invention uses a composite wire structure combining Pd filaments (for N2O decomposition) with Pt or Pt-rich alloy filaments (for mechanical strength). This composite approach allows the gauze to simultaneously achieve N2O reduction capability and sufficient mechanical strength to prevent breaks during use, resolving the contradiction between chemical functionality and structural integrity.
2Object-generated harmful factors
If Pd-based catalyst gauze is used for N2O reduction, then N2O decomposition is improved, but technical life deteriorates due to surface blocking by Pt and Rh collection
Solution Approach 1:
The composite wire structure separates functions: Pd filaments handle N2O decomposition while Pt/Pt-rich alloy filaments handle Pt and Rh collection. This functional separation prevents the Pd surface from being blocked by collected precious metals, maintaining N2O decomposition activity throughout the gauze's technical life and resolving the contradiction between catalytic function and operational duration.
Solution Approach 2:
The invention segments the catalytic functions by assigning different metal filaments to different tasks within the same wire structure. Pd segments handle N2O reduction while Pt segments handle precious metal collection, allowing each function to operate independently without interference, thus extending technical life while maintaining N2O decomposition capability.
3Ease of manufacture
If single filament wire is used for catalyst gauze, then manufacturing simplicity is maintained, but catalytic activity deteriorates due to insufficient contact surface area
Solution Approach 1:
The composite wire structure combines multiple filaments of different materials (Pd and Pt/Pt-rich alloy) into a single manufacturable wire product. This approach increases the contact surface area for catalysis while maintaining ease of manufacture, as the composite wire can be produced using standard wire drawing and weaving processes. The multi-filament construction provides higher catalytic activity without complicating the manufacturing workflow.
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 twisted wire design improves catalytic activity and NO selectivity, extending the lifespan of catalyst gauzes and reducing the need for Pd-based gauzes to capture N2O, thereby enhancing the efficiency and sustainability of ammonia oxidation processes.
Implementation Method 1
A wire for manufacturing catalyst gauzes... each of said filaments comprises at least 50% by weight of Pt... enhancing catalytic activity and NO selectivity
Implementation Method 2
twisted together to increase the contact surface area and density, enhancing catalytic activity
Data Source
Figure 1
Figure 2a~3ii
AI summary
Wire for weaving or knitting a catalyst gauze, said wire being characterized in that it is a stranded wire comprising an assembly of n intertwined filaments, n being an integer with 2 ≤ n ≤ 8, wherein each of said filaments comprises Pt or a Pt alloy constituted of at least 50% by 5 weight of Pt, said filaments being twisted together over their length so that each of the filaments is wound to at least one other filament.