Exhaust Gas Catalyst Barrier Particles Prevent Aggregation
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Solution Overview
Problem
Existing exhaust gas purifying catalysts face issues such as decreased catalyst activity due to aggregation of transition metal oxide particles caused by heat history, insufficient activity at low temperatures, and difficulty in activating catalysts containing noble metals like rhodium, which results in reduced purifying effectiveness.
Innovation Solution
The development of an exhaust gas purifying catalyst comprising a monolithic substrate with a transition metal oxide layer that includes transition metal oxide particles supported by promoter particles and surrounded by barrier particles, where the promoter particles are oxides like cerium, zirconium, or lanthanum, and the barrier particles are alumina or silicon dioxide, preventing aggregation and maintaining catalyst activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transition metal oxide particles are used to reduce noble metal content, then manufacturing cost is reduced, but catalyst activity decreases due to particle aggregation from heat history
Solution Approach 1:
The patent introduces a barrier particle layer as an intermediary substance between transition metal oxide particles. This barrier layer physically prevents direct contact and aggregation of the transition metal oxide particles during heat treatment, thereby maintaining catalyst activity while allowing the use of cost-effective transition metal oxides instead of expensive noble metals.
Solution Approach 2:
The patent creates a composite catalyst structure consisting of transition metal oxide particles dispersed on a carrier particle surface, with barrier particles forming a protective layer. This composite structure combines the cost advantage of transition metal oxides with the stability provided by the barrier layer, resolving the contradiction between manufacturing cost and catalyst activity.
2Ease of manufacture
If transition metal oxide particles are used to reduce noble metal content, then manufacturing cost is reduced, but purifying effectiveness decreases due to particle aggregation
Solution Approach 1:
The barrier particle layer serves as a mediator that prevents aggregation of transition metal oxide particles, thereby maintaining the purifying effectiveness of the catalyst while allowing the use of cheaper transition metal oxides instead of noble metals.
Solution Approach 2:
The patent applies barrier particles specifically at the interfaces between transition metal oxide particles and the carrier, creating localized protection where aggregation would occur. This targeted approach maintains purifying effectiveness at critical locations while keeping overall manufacturing costs low.
3Temperature
If catalyst is designed for low temperature operation, then purifying efficiency at low temperature is improved, but catalyst activation becomes difficult
Solution Approach 1:
The patent modifies the physical and chemical parameters of the catalyst system by introducing barrier particles with specific properties (appropriate size, composition, and thermal stability). These parameter changes enable the catalyst to achieve both easy activation and effective low-temperature operation, as the barrier particles prevent aggregation that would otherwise require higher activation temperatures.
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 effectively inhibits the aggregation of transition metal oxide particles, maintains catalyst activity, and enhances purifying efficiency, especially at low temperatures, while reducing the need for noble metals, thus improving the overall performance and cost-effectiveness of the catalyst.
Implementation Method 1
transition metal oxide particles (10) supported by promoter particles (20)
Implementation Method 2
a second compound (30) that surrounds a single body or an aggregate of the transition metal oxide particles (10) and the first compound (20)
Implementation Method 3
exhaust gas purifying catalyst utilizing a transition metal oxide in order to reduce the amount of noble metal to be used
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An exhaust gas purifying catalyst includes a monolithic substrate (2), and a transition metal oxide layer (3) formed in the monolithic substrate (2). The transition metal oxide layer (3) contains transition metal oxide powder including: transition metal oxide particles (10); a first compound (20) on which the transition metal oxide particles (10) are supported; and a second compound (30) that surrounds a single body or an aggregate of the transition metal oxide particles (10) and the first compound (20).