Rhodium Barium Exhaust Catalyst Spatial Distribution
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Solution Overview
Problem
Current catalysts for purifying exhaust gas from internal-combustion engines, particularly those using Rhodium (Rh) for NOx purification, face challenges in maintaining high purification performance while minimizing the use of scarce and expensive Rh, and optimizing the distribution of Rh and Barium (Ba) components to prevent decreased NOx purification efficiency.
Innovation Solution
A catalyst configuration featuring a Rhodium-supported porous inorganic oxide and barium sulfate supported on alumina, with a specific Rh-Ba deviation rate of 10% to 80%, ensuring independent distribution of Rh and Ba within the catalyst layer, is employed. This configuration is achieved by preparing barium sulfate through specific methods that prevent excessive dispersion and ensure optimal interaction between Rh and Ba, enhancing NOx purification performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of Rhodium is decreased to reduce cost and protect resources, then the purification performance of NOx deteriorates
Solution Approach 1:
The patent changes the distribution parameter of Rhodium and Barium by controlling their spatial separation (Rh-Ba deviation rate of 10-80%). This parameter change allows maintaining effective catalytic function with reduced Rhodium quantity by optimizing where Rhodium atoms are located relative to Barium sites, thereby resolving the contradiction between reducing Rhodium amount and maintaining NOx purification performance.
Solution Approach 2:
The patent applies local quality by creating specific zones within the catalyst layer where Rhodium is positioned at a controlled distance from Barium. This local optimization of Rhodium distribution ensures that each Rhodium atom is in an optimal position for NOx purification, allowing reduced overall Rhodium content while maintaining high purification efficiency.
2Device complexity
If Rhodium and Barium are uniformly distributed to simplify catalyst structure, then the NOx purification efficiency decreases due to excessive interaction between Rh and Ba
Solution Approach 1:
The patent introduces asymmetry in the distribution of Rhodium and Barium by controlling their spatial separation. Instead of uniform distribution, Rhodium is positioned with a specific deviation from Barium locations (Rh-Ba deviation rate of 10-80%). This asymmetric arrangement reduces excessive Rh-Ba interaction while maintaining catalyst structural integrity, thereby improving NOx purification efficiency without significantly increasing structural complexity.
3Productivity
If Rhodium and Barium are closely distributed to maximize catalytic interaction, then the NOx purification performance decreases due to interference with Rh function
Solution Approach 1:
The patent introduces a spatial intermediary distance between Rhodium and Barium, controlled by the Rh-Ba deviation rate. This intermediary separation prevents direct excessive interaction that would interfere with Rhodium's catalytic function while still allowing sufficient interaction for effective NOx purification. The controlled distance acts as an optimal intermediary that resolves the contradiction between catalytic interaction and purification performance.
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 superior NOx purification performance, particularly in gasoline engines, by maintaining Rh and Ba functionality while reducing the amount of expensive Rh used, thus lowering production costs and improving exhaust gas treatment efficiency across varying CO/NO ratios and temperatures.
Implementation Method 1
it is considered that, for example, a steam reforming reaction or a (CO + NO) reaction is promoted via the Rh component
Implementation Method 2
HC+H 2 O → COx+H 2
Implementation Method 3
H 2 + NO x → N 2 +H 2 O
Implementation Method 4
The Ba component is converted to Ba(NO 3 ) 2 by temporarily storing NO x contained in exhaust gas
Implementation Method 5
Ba(NO 3 ) 2 with carbon dioxide gas under co-existence of steam, to be converted to BaCO 3
Implementation Method 6
Cerium oxide stores oxygen as CeO 2 , when oxygen concentration is high in exhaust gas, and releases oxygen by being converted to Ce 2 O 3 , when oxygen concentration is low
Implementation Method 7
a catalytically active species superior in oxidation activity, of Pt, Pd or the like
Data Source
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AI summary
The invention discloses a catalyst for purifying exhaust gas apparatus having a Three-way Catalyst (TWC) superior in purification performance of, particularly, NOx, among carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx), in exhaust gas discharged from a gasoline automobile. It is provided by a catalyst for purifying exhaust gas containing a Rhodium (Rh)-supported porous inorganic oxide and barium sulfate (BaSO4), with supported or not-supported onto alumina, characterized in that at least a part of Rh is present independently from Ba inside a catalyst layer, and Rh-Ba deviation rate determined from EPMA analysis is 10% to 80%. It is preferable that supported amount of Rhodium is 0.05 g/L to 2.0 g/L, and amount of barium sulfate is 0.5 g/L to 25 g/L and 0.5 g/L to 15 g/L, in the case of being supported and not-supported onto alumina, respectively.