Exhaust Gas Catalyst Segmentation for NOx Purification
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Solution Overview
Problem
Conventional exhaust gas purifying catalysts face inefficiencies in nitrogen oxide purification, especially when oxygen levels are excessive or air-fuel ratios vary, leading to decreased purification efficiency.
Innovation Solution
The catalyst employs anchor/promoter simultaneous enclosure particles with noble metal particles supported on anchor particles and separate promoter particles having oxygen storage capacity, enclosed by an enclosure material that prevents aggregation and maintains surface area, along with second promoter particles for effective oxygen management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If promoter component particles are covered with heat resistant oxide to suppress aggregation, then durability is improved, but oxygen penetrates too deeply into the catalyst layer reducing NOx purification efficiency
Solution Approach 1:
The catalyst layer is segmented into multiple functional layers: a promoter layer containing promoter component particles covered with heat resistant oxide (for durability), and a catalyst layer containing catalyst particles with noble metal particles (for NOx purification). This segmentation allows each layer to perform its specific function optimally without interfering with the other.
Solution Approach 2:
The promoter component particles covered with heat resistant oxide act as an intermediary layer between the exhaust gas and the catalyst particles. This intermediary structure maintains the durability benefits of covered promoter particles while preventing excessive oxygen penetration to the catalyst layer, thus preserving NOx purification efficiency.
2Productivity
If catalyst powder is coated on honeycomb substrate to form catalyst layer, then catalytic activity is achieved, but air-fuel ratio variation cannot be suppressed leading to decreased purifying efficiency
Solution Approach 1:
The catalyst system is divided into distinct functional components: promoter component particles (for oxygen storage and air-fuel ratio buffering), heat resistant oxide coating (for structural stability), and catalyst particles with noble metals (for catalytic reactions). This segmentation allows the promoter layer to handle air-fuel ratio variations independently while the catalyst layer maintains stable catalytic activity.
Solution Approach 2:
The catalyst layer comprises composite structures where catalyst particles contain noble metal particles supported on metal oxide particles, and promoter component particles are covered with heat resistant oxide. This composite material design provides both the catalytic activity needed for NOx purification and the oxygen storage capacity to buffer air-fuel ratio variations.
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
This configuration enhances nitrogen oxide purification efficiency by preventing oxygen deep penetration and maintaining catalytic activity, even under varying oxygen conditions, and ensures effective NOx conversion rates.
Implementation Method 1
first promoter particles having an oxygen storage and release capacity
Implementation Method 2
catalyst units which contain: noble metal particles; and anchor particles as an anchor material of the noble metal particles supporting the noble metal particles
Implementation Method 3
anchor particles as an anchor material of the noble metal particles supporting the noble metal particles
Data Source
Figure 1(a)~1(d)
Figure 2
Figure 3~4
AI summary
An exhaust gas purifying catalyst (1) of the present invention includes anchor/promoter simultaneous enclosure particles (5) including catalyst units (13) which contain: noble metal particles (8); and anchor particles (9) as an anchor material of the noble metal particles (8) supporting the noble metal particles (8); promoter units (14) which are provided not in contact with the noble metal particles (8) and contain first promoter particles (11) having an oxygen storage and release capacity; and an enclosure material (12) which encloses both the catalyst units (13) and the promoter units (14), and separates the noble metal particles (8) and the anchor particles (9) in the catalyst units (13) from the first promoter particles (11) in the promoter units (14). The exhaust gas purifying catalyst (1) further includes second promoter particles (6) which have the oxygen storage and release capacity, and are not enclosed in the anchor/promoter simultaneous enclosure particles (5) by the enclosure material (12).