Phosphorus-Resistant Three-Way Catalyst with Rhodium Trap
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Solution Overview
Problem
Three-way conversion catalysts in exhaust gas treatment systems are prone to deactivation due to phosphorus-containing species from engine oil, leading to reduced efficiency in converting hydrocarbons, carbon monoxide, and nitrogen oxides, and existing solutions like phosphorus traps become saturated, necessitating a more durable and efficient catalyst composition.
Innovation Solution
A three-way conversion catalytic article with enhanced phosphorus resistance, featuring a phosphorus trap material and a rhodium component impregnated on a phosphorus-resistant support material, such as zirconia-based lanthana-zirconia, to adsorb and neutralize phosphorus impurities, maintaining catalytic activity and preventing sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guard or filter is installed in front of the catalyst components to prevent poisoning by phosphorus-containing species, then the catalyst is protected from deactivation, but the guard or filter becomes saturated with phosphorus over time and loses its protective capability
Solution Approach 1:
The patent extracts the phosphorus-trapping function from a separate guard component and integrates it directly into the catalyst structure by impregnating the catalyst support material with phosphorus-trapping compounds. This eliminates the need for a separate guard that becomes saturated, as the trapping capacity is distributed throughout the catalyst itself.
Solution Approach 2:
The patent merges the phosphorus-trapping function with the catalyst structure by combining the catalytic active sites with phosphorus-trapping materials on the same support. This integration ensures that the catalyst maintains both its catalytic activity and phosphorus resistance simultaneously, rather than requiring a separate protective layer.
2Productivity
If the catalytic activity is increased to meet stricter emissions regulations, then the pollutant conversion efficiency improves, but the catalyst becomes more susceptible to deactivation by phosphorus-containing species
Solution Approach 1:
The patent uses composite materials by combining catalytic components with phosphorus-trapping materials on a common support structure. This composite approach allows the catalyst to simultaneously achieve high pollutant conversion efficiency through the catalytic components and strong phosphorus resistance through the trapping materials, resolving the contradiction between productivity and reliability.
3Productivity
If platinum group metal loading is increased to compensate for reduced catalyst activity, then the pollutant conversion is maintained, but the cost of the catalyst increases and the catalyst remains susceptible to phosphorus poisoning
Solution Approach 1:
The patent converts the harmful effect of phosphorus into a beneficial trapping mechanism by using phosphorus-trapping materials that selectively bind phosphorus species. This prevents phosphorus from deactivating the expensive platinum group metals, allowing the use of lower metal loadings while maintaining high conversion efficiency and reducing overall catalyst cost.
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 catalytic article effectively reduces phosphorus poisoning, maintaining high conversion efficiency for hydrocarbons, carbon monoxide, and nitrogen oxides, with the phosphorus-resistant support material ensuring long-term durability and performance even under increased engine mileage and stringent emissions regulations.
Implementation Method 1
a phosphorus trap material to adsorb at least a portion of the phosphorus-containing impurities
Implementation Method 2
Phosphorus-resistant support materials prevent the catalytically active metals from sintering when exposed to engine exhaust containing phosphorus impurities
Implementation Method 3
a rhodium component impregnated on a phosphorus-resistant support material; the catalytic material is effective for three-way conversion to oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides
Implementation Method 4
the catalytic material is effective for three-way conversion to oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides
Data Source
AI summary
Described are three-way conversion (TWC) catalytic articles effective to abate hydrocarbons (HCs), carbon monoxide (CO), and nitrogen oxides (NOx) from an engine exhaust gas containing phosphorous impurities. The disclosed catalytic article has a layered catalytic material, wherein the first layer of the catalytic material is disposed directly on the substrate and a second layer is disposed on top of the first layer. The second layer includes phosphorus resistant materials that prevent catalytic poisoning of the catalytic article by the phosphorous impurities. In particular, the second layer includes a phosphorus trap material having an alkaline earth metal component and a rhodium component impregnated on a phosphorus-resistant support material.