Exhaust Gas Catalyst Body With Proton-Type Zeolite for Durable NH3 Removal
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Solution Overview
Problem
Existing catalysts using Cu-CHA zeolite for NH3 adsorption in gasoline engines fail to meet stringent emission regulations due to insufficient NH3 purifying performance after endurance, particularly at high temperatures and fluctuating atmospheres, leading to metal elution and structural degradation.
Innovation Solution
A catalyst body for gasoline engines featuring a proton-type zeolite with a basic skeleton of 4-, 6-, and 8-membered rings, located closer to the base material than the catalyst layer, enhances NH3 adsorption intensity and stability, using CHA-type or AFX-type zeolite with Rh, Pd, or Pt as catalyst noble metals, and a multilayer structure for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Cu-CHA zeolite is used as NH3 adsorbent, then NH3 adsorption capacity is provided, but NH3 purifying performance after endurance becomes insufficient at high temperatures
Solution Approach 1:
The patent changes the chemical composition parameter by replacing Cu-CHA zeolite with proton-type zeolite (H-CHA) that has different acid site characteristics. This parameter change resolves the contradiction by providing NH3 adsorption capacity through proton-type zeolite while maintaining stability and purifying performance after endurance testing at high temperatures (350-600°C) in gasoline engine exhaust conditions.
2Quantity of substance
If metal-containing zeolite is used for NH3 adsorption, then NH3 adsorption capacity is enhanced, but metal elution occurs at high temperatures causing structural degradation
Solution Approach 1:
The patent extracts the metal component (Cu) from the zeolite structure, using only proton-type zeolite (H-CHA) without metal carriers. This extraction eliminates the source of metal elution and structural degradation while maintaining NH3 adsorption capacity through the proton-type zeolite's acid sites, thereby resolving the contradiction between adsorption capacity and structural stability.
3Ease of manufacture
If conventional zeolite structure is used, then manufacturing is simpler, but NH3 adsorption intensity is insufficient at high temperatures
Solution Approach 1:
The patent changes the zeolite type parameter from conventional metal-containing zeolite to proton-type zeolite (H-CHA) with specific pore structure parameters. This parameter change maintains manufacturability while significantly enhancing NH3 adsorption intensity at high temperatures (350-600°C) by utilizing the proton-type zeolite's acid sites, which are more effective for NH3 adsorption under gasoline engine 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 catalyst body achieves enhanced NH3 purifying performance after endurance by increasing adsorption capacity and preventing metal elution, ensuring high efficiency in the temperature range of 350° C. to 600° C. and varying atmospheres.
Implementation Method 1
an NH3 adsorption layer containing proton-type zeolite
Implementation Method 2
a catalyst layer containing a catalyst noble metal
Data Source
AI summary
An exhaust gas purification catalyst body for gasoline engine, having a high NH3 purifying performance after endurance, is provided. The exhaust gas purification catalyst body for gasoline engine, disclosed herein, is configured to be placed in an exhaust path for the gasoline engine. The exhaust gas purification catalyst body includes a base material, an NH3 adsorption layer containing proton-type zeolite, and a catalyst layer containing a catalyst noble metal. The NH3 adsorption layer is stacked with the catalyst layer so as to be located closer to the base material than the catalyst layer. The proton-type zeolite has a basic skeleton substantially consisting of 4-, 6-, and 8 membered rings.