Three-Layer Exhaust Gas Oxidation Catalyst Sulfur Resistance
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Solution Overview
Problem
Existing exhaust gas oxidation catalysts for diesel engines face challenges in maintaining effective hydrocarbon adsorption during low-speed running and are susceptible to sulfur poisoning, leading to inadequate CO removal.
Innovation Solution
A three-layer catalyst structure is implemented, with a bottom layer containing an oxygen-occluding agent, an intermediate layer with a catalyst metal supported on a metal oxide and a hydrocarbon adsorbent, and a top layer also containing oxygen-occluding and hydrocarbon adsorbent agents, enhancing adsorption and resistance to sulfur poisoning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a catalyst layer containing molecular sieve and noble metal is used to increase HC adsorption at low temperature, then HC adsorption capability is improved, but HC adsorption efficacy deteriorates during continuous low temperature running and CO removal becomes insufficient
Solution Approach 1:
The catalyst layer is divided into three distinct layers: a bottom layer containing oxygen storage component and hydrocarbon adsorbent, an intermediate layer containing catalyst metal and hydrocarbon adsorbent, and a top layer containing oxygen storage component and hydrocarbon adsorbent. This segmentation allows each layer to perform specific functions, with the bottom and top layers providing oxygen storage and adsorption, and the intermediate layer providing catalytic conversion, thereby maintaining stable HC adsorption and CO removal performance during continuous low temperature running.
Solution Approach 2:
The catalyst layer uses composite materials combining oxygen storage components (such as cerium oxide), hydrocarbon adsorbents (such as zeolite), and catalyst metals (such as platinum or palladium) supported on metal oxide. This composite structure enables the catalyst to simultaneously perform oxygen storage, hydrocarbon adsorption, and catalytic conversion functions, improving both HC adsorption capability and stability during continuous operation.
2Quantity of substance
If a catalyst layer with high HC adsorption capacity is used, then HC removal is improved, but the catalyst becomes susceptible to sulfur poisoning and recovery from sulfur poisoning is slow
Solution Approach 1:
The catalyst layer is segmented into three layers with the intermediate layer containing catalyst metal and hydrocarbon adsorbent positioned between the bottom and top layers containing oxygen storage components. This segmentation protects the catalyst metal from direct exposure to sulfur compounds by placing it between two protective layers, reducing sulfur poisoning susceptibility while maintaining high HC removal efficiency.
Solution Approach 2:
The bottom and top layers containing oxygen storage components and hydrocarbon adsorbents serve as protective barriers that cushion the intermediate catalyst layer from sulfur poisoning before sulfur compounds reach the catalyst metal. This beforehand cushioning reduces sulfur poisoning susceptibility and enables faster recovery from sulfur poisoning while maintaining high HC removal efficiency.
3Device complexity
If a simple single-layer catalyst structure is used, then device complexity is reduced, but CO removal efficiency and resistance to sulfur poisoning are insufficient
Solution Approach 1:
The catalyst layer is segmented into three distinct layers: a bottom layer with oxygen storage component and hydrocarbon adsorbent, an intermediate layer with catalyst metal and hydrocarbon adsorbent, and a top layer with oxygen storage component and hydrocarbon adsorbent. This segmentation provides a straightforward manufacturing process while achieving high CO removal efficiency and sulfur resistance through the synergistic functions of each layer.
Solution Approach 2:
The catalyst layer uses composite materials combining oxygen storage components (such as cerium oxide), hydrocarbon adsorbents (such as zeolite), and catalyst metals (such as platinum or palladium) supported on metal oxide. This composite structure enables the catalyst to simultaneously perform oxygen storage, hydrocarbon adsorption, and catalytic conversion functions, improving both HC adsorption capability and stability during continuous operation.
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 catalyst achieves improved CO and HC removal efficiency, maintains adsorption performance during low-speed running, and rapid recovery from sulfur poisoning, effectively oxidizing harmful substances in exhaust gases.
Implementation Method 1
the bottom catalyst layer contains at least an oxygen occluding agent as catalyst component
Implementation Method 2
the intermediate layer contains at least a catalyst metal, supported on a metal oxide support, and a hydrocarbon adsorbent as catalyst components
Implementation Method 3
the intermediate layer contains at least a catalyst metal, supported on a metal oxide support
Implementation Method 4
An oxidation catalyst renders the noxious substances in exhaust gas, such as carbon monoxide (CO), unburned hydrocarbon (HC), and soluble organic fraction (SOF), harmless by decomposition to carbon dioxide, water, etc.
Data Source
AI summary
An exhaust gas oxidation catalyst characterised as an exhaust gas oxidation catalyst comprising a catalyst substrate, wherein a plurality of exhaust gas channels has been formed, and a catalyst layer formed on the surface of the exhaust gas channels in the catalyst substrate; wherein a catalyst layer consisting of a bottom catalyst layer, a top catalyst layer exposed within the exhaust gas channels, and an intermediate catalyst layer located between the bottom catalyst layer and top catalyst layer, is provided so as to cover not less than 25% of the exhaust gas channel surface, and wherein the bottom catalyst layer contains at least an oxygen-occluding agent as catalyst component but does not contain a hydrocarbon adsorbent, the intermediate catalyst layer contains at least catalyst metal, supported on a metal oxide support, and a hydrocarbon adsorbent as catalyst components, and the top catalyst layer contains at least an oxygen-occluding agent and a hydrocarbon adsorbent as catalyst components.