Gas Sensor Preliminary Pump Electrode High Oxygen
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Solution Overview
Problem
Conventional gas sensors fail to accurately measure the concentrations of ammonia and nitrogen oxide when the oxygen concentration in the gas to be measured is high, as the change in pumping current at the measurement electrode does not appear, preventing the segregation and separate measurement of these gas components.
Innovation Solution
A gas sensor with a structural body made of oxygen ion conductive solid electrolyte, featuring a preliminary chamber, main chamber, auxiliary chamber, and measurement chamber, along with specific pump electrodes and concentration control units, where the preliminary pump electrode is made of an Au/Pt alloy with a high Au concentration to minimize reaction activity with oxygen, allowing for accurate measurement even at high oxygen concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gas sensor uses a preliminary pump electrode with high reaction activity (e.g., platinum) to facilitate ammonia oxidation, then the oxidation reaction proceeds efficiently, but the sensor fails to detect changes in pumping current when oxygen concentration is high, preventing separate measurement of ammonia and nitrogen oxide
Solution Approach 1:
The patent changes the material parameter of the preliminary pump electrode from highly active catalysts (platinum) to gold-containing alloys with lower reaction activity. This parameter change allows the electrode to maintain lower activity even at high oxygen concentrations, preserving the sensor's ability to detect pumping current changes and separately measure ammonia and nitrogen oxide concentrations.
Solution Approach 2:
The patent employs composite materials (gold-containing alloys) for the preliminary pump electrode instead of single-material catalysts. These composite materials exhibit optimized reaction activity that is sufficient for ammonia oxidation under normal conditions but does not cause excessive reaction rates that would mask detection sensitivity at high oxygen concentrations.
2Measurement precision
If the preliminary pump electrode is made with low reaction activity to prevent excessive ammonia oxidation, then detection sensitivity is maintained, but the oxidation reaction efficiency decreases
Solution Approach 1:
The patent optimizes the reaction activity parameter of the preliminary pump electrode by selecting gold-containing alloys with specific composition ranges. This parameter optimization ensures that the electrode has sufficient activity to oxidize ammonia effectively while maintaining lower activity than traditional platinum catalysts, thereby preserving detection sensitivity even when oxygen concentration is high.
3Adaptability or versatility
If the gas sensor operates under high oxygen concentration conditions, then the sensor can handle varied exhaust gas compositions, but the change in pumping current at the measurement electrode does not appear, preventing separate measurement of gas components
Solution Approach 1:
The patent changes the material parameter of the preliminary pump electrode to gold-containing alloys with lower reaction activity. This parameter change enables the sensor to maintain distinct pumping current signals even when operating under high oxygen concentration conditions, thereby preserving the ability to separately measure ammonia and nitrogen oxide concentrations while adapting to varied exhaust gas compositions.
Data Source
AI summary
A gas sensor includes a structural body made up from a solid electrolyte that exhibits oxygen ion conductivity, a gas introduction port formed in the structural body, a preliminary chamber communicating with the gas introduction port and equipped with a preliminary pump electrode, a main chamber communicating with the preliminary chamber and equipped with a main pump electrode, and a measurement chamber communicating with the main chamber and equipped with a measurement electrode. In the gas sensor, at least a surface of the preliminary pump electrode is made of a material which exhibits a low activity with respect to a reaction between ammonia and oxygen.