Alpha Alumina Three-Way Catalyst Support for Reduced PGM Sintering
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Solution Overview
Problem
Conventional alumina-based three-way catalysts (TWCs) face challenges in maintaining catalytic activity after high-temperature ageing, particularly when subjected to extreme temperatures above 900°C, as gamma alumina support materials suffer from high-temperature thermal instability and PGM sintering, leading to reduced catalytic performance.
Innovation Solution
The use of alpha alumina as a support material in combination with an oxygen storage capacity (OSC) material in the catalytic region of TWCs, which maintains catalytic activity and reduces PGM sintering, even after high-temperature ageing, allowing for lower PGM loadings while achieving equivalent catalytic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gamma alumina is used as support material to provide high surface area for PGM dispersion, then catalytic activity is improved, but thermal stability above 900°C deteriorates
Solution Approach 1:
The patent changes the alumina phase from gamma to alpha, which fundamentally alters the thermal stability parameter while maintaining catalytic functionality through the oxygen storage component
Solution Approach 2:
The patent creates a composite catalytic system combining alpha alumina support with oxygen storage capacity material (such as cerium oxide), where the composite achieves both thermal stability and catalytic activity that neither component could provide alone
2Ease of manufacture
If PGM loading is reduced to lower cost, then manufacturing cost is improved, but catalytic activity deteriorates
Solution Approach 1:
The oxygen storage capacity material acts as an intermediary that enhances the efficiency of PGM utilization, allowing lower PGM loadings to achieve equivalent catalytic performance through improved oxygen management during exhaust fluctuations
3Reliability
If high-temperature ageing is endured to simulate real operating conditions, then durability is improved, but PGM sintering increases leading to catalytic performance loss
Solution Approach 1:
The patent provides beforehand cushioning against thermal degradation by using alpha alumina's inherent high-temperature stability to prevent PGM sintering before it can occur, maintaining catalytic performance after ageing at temperatures above 900°C
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
Alpha alumina support materials enhance HC, CO, and NOx conversion in TWCs, reducing the total hydrocarbon, CO, and NOx light-off temperatures, and increasing N2 selectivity, even after prolonged exposure to high temperatures.
Implementation Method 1
alpha alumina support materials enhance HC, CO, and NOx conversion in TWCs, reducing the total hydrocarbon, CO, and NOx light-off temperatures, and increasing N2 selectivity, even after prolonged exposure to high temperatures
Implementation Method 2
the oxygen storage component that liberates or absorbs oxygen during the perturbations. The most commonly used oxygen storage component in modern TWCs is cerium oxide (CeO2) or a mixed oxide containing cerium
Implementation Method 3
TWCs are intended to catalyse three reactions simultaneously: (i) oxidation of carbon monoxide to carbon dioxide, (ii) oxidation of unburned hydrocarbons to carbon dioxide and water; and (iii) reduction of nitrogen oxides to nitrogen and oxygen
Implementation Method 4
having a high surface area support material, such as gamma alumina, can provide excellent dispersion of the PGM on the support material, which provides more PGM active sites for catalysing the TWC reactions
Data Source
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AI summary
Provided is a catalyst article for treating exhaust gas, the catalyst article comprising a substrate and at least a first catalytic region disposed on the substrate, wherein the first catalytic region comprises: an oxygen storage capacity (OSC) material; and an alumina support material having at least one platinum group metal (PGM) supported thereon; wherein the alumina support material comprises alpha alumina.