Gasoline Exhaust Catalyst Stack for Durable NH3 Purification
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Solution Overview
Problem
Conventional exhaust gas purifying systems for gasoline engines using zeolites with NH3 adsorbing capability suffer from deteriorating NH3 purifying performance due to zeolite structure degradation under high temperature and low oxygen concentration in rich to stoichiometric regions.
Innovation Solution
The system incorporates an OSC material in the catalyst layer stacked on the NH3 adsorption layer containing CHA-type zeolite with Cu, ensuring oxygen supply to the zeolite even in low oxygen environments, thereby maintaining high NH3 purifying performance over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a zeolite with NH3 adsorbing capability is introduced into the exhaust gas purifying system, then the NH3 purifying performance is improved, but the zeolite structure deteriorates under high temperature and low oxygen concentration conditions, causing the NH3 purifying performance to decrease after duration
Solution Approach 1:
An OSC material layer is introduced as an intermediary between the exhaust gas and the zeolite layer. This intermediary layer supplies oxygen to the zeolite under high temperature conditions, preventing the zeolite structure deterioration that would otherwise occur in low oxygen concentration environments, thereby maintaining NH3 purifying performance after duration
Solution Approach 2:
The exhaust gas purifying system uses a composite structure combining OSC material and zeolite in distinct layers. The OSC material layer provides oxygen storage and release capabilities, while the zeolite layer provides NH3 adsorption, creating a synergistic system that maintains both high NH3 purifying performance and zeolite structure stability under varying exhaust conditions
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 solution effectively suppresses zeolite structure deterioration and maintains high NH3 purifying performance by providing oxygen to the zeolite layer, enhancing durability and efficiency in high temperature and varying atmospheric conditions.
Implementation Method 1
the catalyst layer containing the OSC material is stacked on the NH3 adsorption layer containing the zeolite. Therefore, even in the rich to stoichiometric region with the low oxygen concentration, oxygen can be supplied from the OSC material to the NH3 adsorption layer
Implementation Method 2
the NH3 adsorption layer containing the zeolite... the zeolite with the NH3 adsorbing capability
Data Source
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AI summary
An exhaust gas purifying system for a gasoline engine with high NH3 purifying performance after duration is provided. The exhaust gas purifying system for a gasoline engine disclosed herein is configured to be disposed in an exhaust path of the gasoline engine. The exhaust gas purifying system includes an upstream catalyst converter including a first catalyst body and a downstream catalyst converter including a second catalyst body. The first catalyst body contains a catalyst precious metal. The second catalyst body has a structure in which an NH3 adsorption layer and a catalyst layer are stacked on a base material. The NH3 adsorption layer of the second catalyst body contains a zeolite as an NH3 adsorber. The catalyst layer of the second catalyst body contains a catalyst precious metal and an OSC material.