Exhaust Gas Purification Catalyst OSC Material Surface Area
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Solution Overview
Problem
The increasing demand for improved exhaust gas purification catalysts due to tightening emission controls and the introduction of Real Driving Emissions (RDE) control has led to higher usage of precious metals and oxygen storage capacity (OSC) materials, but this results in initial OSC levels that are too high, making air/fuel ratio learning and on-board diagnosis difficult, and reducing the durability of the catalyst.
Innovation Solution
By adjusting the specific surface area of the oxygen storage capacity (OSC) material, specifically a ceria-zirconia composite oxide, to a range of 40 to 60 m2/g, the initial OSC amount can be effectively suppressed, and the OSC retention rate after long-term use can be maintained, thereby achieving stable air/fuel control and extended durability of the catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of OSC material is increased to improve exhaust gas purification performance, then the catalytic ability is improved, but the initial OSC level becomes too high, making air/fuel ratio learning and on-board diagnosis difficult
Solution Approach 1:
The patent changes the physical parameter of the OSC material by controlling its specific surface area to be within 30-70 m²/g. This parameter change allows the material to provide sufficient OSC capacity for purification while limiting the initial OSC level to prevent interference with air/fuel ratio learning and diagnosis systems.
2Reliability
If the amount of precious metal and OSC material is increased to meet tightening emission controls, then the catalytic ability is improved, but the durability of the catalyst is reduced
Solution Approach 1:
The patent optimizes the specific surface area parameter of the OSC material to balance catalytic activity and durability. By setting the specific surface area within 30-70 m²/g, the catalyst maintains high purification performance while achieving durable vehicle mileage extension, resolving the trade-off between initial performance and long-term durability.
3Quantity of substance
If the specific surface area of OSC material is increased to improve OSC capacity, then the oxygen storage capacity is enhanced, but the initial OSC amount becomes too high, affecting air/fuel ratio control
Solution Approach 1:
The patent precisely controls the specific surface area parameter of the OSC material within the range of 30-70 m²/g. This optimization ensures that the oxygen storage capacity is sufficient for effective air/fuel ratio control, while the initial OSC level remains at appropriate levels to allow proper learning and diagnosis operations.
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 adjusted OSC material with a lower specific surface area effectively suppresses initial OSC levels and maintains OSC retention over time, ensuring stable air/fuel control and prolonged catalyst performance, even under varying driving conditions.
Implementation Method 1
a Ce-containing oxide (e.g. ceria-zirconia composite oxide) having an oxygen storage capacity (OSC) has been widely used as a carrier for the above precious metal
Implementation Method 2
stable performance of oxidation-reduction catalyst for exhaust gas can be obtained
Data Source
AI summary
According to a technique disclosed herein, provided is an exhaust gas purification catalyst, which both suppresses OSC when using a new vehicle and maintains OSC during life cycles. The exhaust gas purification catalyst disclosed herein is an exhaust gas purification catalyst includes a substrate, and a catalyst coated layer formed on the surface of the substrate, wherein the catalyst coated layer contains an OSC material having an oxygen storage capacity. The catalyst coated layer includes a Rh layer mainly containing Rh as a catalyst metal, and a Pd/Pt layer mainly containing Pd and/or Pt as a catalyst metal. At least a portion of the Pd/Pt layer in the catalyst coated layer contains, as the OSC material, a low specific surface area OSC material, including a ceria-zirconia composite oxide and having a specific surface area of 40 m2/g or more and 60 m2/g or less.