Rhodium Alloy Catalyst Inhibits Sintering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Exhaust cleaning catalysts using precious metals like rhodium, palladium, and platinum face degradation due to sintering at high temperatures, leading to reduced cleaning abilities, as existing techniques primarily focus on inhibiting carrier sintering rather than the precious metals themselves.
Innovation Solution
An exhaust cleaning catalyst with Rh-containing metal particles, where rhodium coexists with a base metal from the platinum group, forming an alloy at high temperatures, inhibiting precious metal sintering and enhancing catalytic cleaning abilities, particularly with an average rhodium content of 0.1% to 5% and a carrier comprising alumina-based or ceria-zirconia-based oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If precious metals are used as catalysts in exhaust cleaning catalysts, then catalytic cleaning ability is improved, but the precious metal degrades through sintering at high temperatures, reducing cleaning ability over time
Solution Approach 1:
The patent applies composite materials by combining rhodium with base metals from the platinum group (such as palladium or platinum) to form Rh-containing metal particles. This composite structure leverages the synergistic effects between different metals: rhodium provides strong catalytic activity for cleaning hydrocarbons and carbon monoxide, while the base metal components help inhibit sintering and maintain structural stability at high temperatures, thereby resolving the contradiction between catalytic performance and durability
Solution Approach 2:
The patent utilizes parameter changes by controlling the rhodium content in the Rh-containing metal particles to be within 0.1% to 5% by mole. This optimized composition parameter allows the catalyst to achieve high cleaning ability while the controlled amount of rhodium prevents excessive sintering. The specific parameter range balances catalytic activity with thermal stability, resolving the contradiction between productivity and reliability
2Stability of the object's composition
If the precious metal undergoes grain growth at high temperatures, then the catalyst remains stable structurally, but the specific surface area decreases, reducing the number of active sites and cleaning ability
Solution Approach 1:
The composite structure of Rh-containing metal particles with controlled rhodium content (0.1% to 5% by mole) provides both structural stability and high specific surface area. The base metals in the composite contribute to structural stability through their lower sintering tendencies, while the rhodium components maintain high catalytic activity on the surface, thus resolving the contradiction between stability and productivity
Solution Approach 2:
The patent applies local quality by creating metal particles with non-uniform composition - specifically, rhodium distributed within base metal matrices. This local compositional variation allows different regions of the particle to serve different functions: areas with higher rhodium content provide catalytic activity while areas with base metals provide structural stability, maintaining both high surface area and stability simultaneously
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 inhibits precious metal sintering, maintaining high catalytic activity and cleaning efficiency for hydrocarbons and carbon monoxide, even in rich atmospheres, with improved durability and energy efficiency.
Implementation Method 1
the precious metal undergoes grain growth, resulting in a decrease in specific surface area (active spots) of the precious metal
Implementation Method 2
After exposed to a high temperature (e.g. after placed and used in an internal combustion system), in the Rh-containing metal particles, some of the base metal and rhodium (Rh) form an alloy
Implementation Method 3
The catalyst coating layer comprises a precious metal that serves as an oxidation and/or reduction catalyst
Implementation Method 4
The catalyst coating layer comprises a precious metal that serves as an oxidation and/or reduction catalyst
Data Source
AI summary
An exhaust cleaning catalyst, with which precious metal sintering is inhibited and which has greater exhaust cleaning abilities, has a substrate and a catalyst coating layer provided on the substrate. The catalyst coating layer has a precious metal that serves as an oxidation and/or reduction catalyst. The precious metal has Rh-containing metal particles in which rhodium (Rh) coexists with a base metal selected among platinum group elements excluding rhodium. The Rh-containing metal particles have an average rhodium content of 0.1% to 5% by mole with the total amount of the base metal and rhodium being 100% by mole.