Knitted Noble Metal Catalyst Net for Low-N2O Ammonia Oxidation
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Solution Overview
Problem
Existing noble metal nets used in catalytic ammonia oxidation processes suffer from high selectivity to nitrous oxide (N2O) formation, which is a greenhouse gas, and require high platinum content, increasing the risk of net breakage and production costs.
Innovation Solution
A method for producing noble metal nets using flat-bed knitting machines, involving the use of combustible or soluble yarns to create loops protruding from the net plane, combined with platinum-rhodium alloy wires, to enhance ammonia conversion to NO and reduce N2O selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high platinum content alloy is used to improve mechanical strength, then mechanical strength is improved, but production costs increase
Solution Approach 1:
The patent changes the chemical composition parameters of the alloy by incorporating ruthenium (0.1-10 wt%) in addition to platinum and rhodium. This parameter modification allows achieving the required mechanical strength with reduced overall noble metal content, thereby resolving the contradiction between mechanical strength and production cost.
Solution Approach 2:
The patent creates a composite alloy material comprising platinum, rhodium, and ruthenium. This composite material combines the high strength of platinum with the cost-effective properties of ruthenium, achieving both improved mechanical strength and reduced platinum usage simultaneously.
2Ease of manufacture
If conventional knitting structure is used, then production is simpler, but selectivity for NO production is low leading to increased nitrous oxide formation
Solution Approach 1:
The patent applies local quality by creating protruding loops at specific locations on the catalyst net surface. These localized structural features with different geometry than the base fabric provide enhanced catalytic activity and selectivity for NO production, while maintaining the overall simplicity of the knitting process.
Solution Approach 2:
The patent transitions from a flat two-dimensional knitting structure to a three-dimensional structure with protruding loops. This dimensional change creates additional catalytic surface area and optimized gas flow paths, improving selectivity for NO production without complicating the manufacturing process.
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 produced noble metal nets exhibit improved selectivity for ammonia oxidation to NO, reduced N2O formation, and lower platinum usage, while maintaining mechanical strength and economic efficiency.
Implementation Method 1
noble metal catalysts in the form of gas-permeable spatial structures, on or in which the reaction takes place
Implementation Method 2
a combustible or soluble yarn is used which is burnt off or dissolved after the knitting process
Data Source
AI summary
The invention relates to a method for producing noble metal nets on flatbed knitting machines, the steps involving—providing noble metal wire comprising platinum—providing yarn that is combustible or soluble in solvent—knitting two-bed items by simultaneous knitting on the front and rear needle beds and joining the two knitted fabrics by means of connecting pile threads, wherein, on the front or on the rear needle bed, a combustible or soluble yarn is used which is burnt off or dissolved after the knitting process, and a noble metal wire is used on the other needle bed and for the pile threads such that, after the combustible or soluble yarn has been burnt off or dissolved, there remain only the pile threads and the knitted fabric made of noble metal wire and produced on the rear or front needle bed.