Layered Catalytic Article for Platinum Sintering Resistance
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Solution Overview
Problem
The need to replace palladium with platinum in three-way conversion (TWC) catalysts to reduce costs while maintaining or improving catalyst efficacy is complicated by platinum's propensity to sinter under high temperature aging conditions, and existing TWC catalysts face challenges in maintaining performance over time.
Innovation Solution
A layered catalytic article comprising a first layer with platinum supported on a ceria-alumina component and a second layer with a platinum group metal component on a refractory alumina component, along with an oxygen storage component, to stabilize platinum and enhance catalyst performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If platinum is used to replace palladium in TWC catalysts to reduce cost, then catalyst cost is reduced, but catalyst stability deteriorates due to platinum sintering under high temperature aging conditions
Solution Approach 1:
The catalyst is divided into two distinct layers: a first layer containing platinum supported on ceria-alumina component, and a second layer containing platinum group metal component on refractory alumina. This segmentation allows the platinum to be stabilized by the ceria-alumina support while maintaining cost effectiveness through selective placement of expensive materials.
Solution Approach 2:
The patent uses a composite ceria-alumina component as the support for platinum in the first layer. This composite material combines the oxygen storage capacity of ceria with the structural stability of alumina, preventing platinum sintering while maintaining catalytic activity. The layered structure itself is a composite of different material systems working together to resolve the contradiction between cost and stability.
2Quantity of substance
If platinum is used to replace palladium to reduce cost, then catalyst cost is reduced, but catalyst performance deteriorates due to inability to maintain desired efficacy
Solution Approach 1:
The catalyst is divided into two distinct layers: a first layer containing platinum supported on ceria-alumina component, and a second layer containing platinum group metal component on refractory alumina. This segmentation allows the platinum to be stabilized by the ceria-alumina support while maintaining cost effectiveness through selective placement of expensive materials.
Solution Approach 2:
The patent uses a composite ceria-alumina component as the support for platinum in the first layer. This composite material combines the oxygen storage capacity of ceria with the structural stability of alumina, preventing platinum sintering while maintaining catalytic activity. The layered structure itself is a composite of different material systems working together to resolve the contradiction between cost and stability.
3Ease of manufacture
If conventional refractory alumina is used as support for platinum, then manufacturing is simplified, but platinum particles grow into submicron size via Oswald ripening mechanism
Solution Approach 1:
The ceria-alumina component acts as an intermediary support material between the platinum catalyst and the refractory alumina structure. The ceria particles disperse on the alumina surface, providing numerous nucleation sites for platinum that prevent Oswald ripening. This intermediary layer maintains manufacturing simplicity while stabilizing platinum particle size through enhanced dispersion and anchoring effects.
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 layered catalytic article provides improved CO, HC, and NOx conversion levels, maintaining catalyst performance even under high temperature aging conditions, thus reducing the reliance on palladium and stabilizing platinum.
Implementation Method 1
platinum particles deposited on a conventional refractory alumina can grow into submicron size via a well-established Oswald ripening mechanism
Implementation Method 2
a first platinum group metal component is supported on the oxygen storage component
Implementation Method 3
The three-way conversion catalyst is typically known to oxidize unburnt hydrocarbons and carbon monoxide and reduce nitrogen oxides
Data Source
AI summary
The presently claimed invention provides a layered catalytic article and an exhaust system. The catalytic article comprises a first layer comprising platinum, a first platinum group metal component other than platinum, a ceria-alumina composite, and an oxygen storage component; wherein platinum is supported on the ceria-alumina component; the platinum group metal component is selected from palladium, rhodium or a combination thereof and the platinum group metal component is supported on the oxygen storage component; a second layer comprising a second platinum group metal component; and a refractory alumina component, an oxygen storage component or a combination thereof; wherein the second platinum group component is selected from platinum, palladium, rhodium or a combination thereof; and a substrate, wherein the amount of platinum is 10 to 80 wt. %, based on the total weight of platinum, palladium and rhodium. The presently claimed invention also provides a process for the preparation of a layered catalytic article and use of the catalytic article and the exhaust system for purifying a gaseous exhaust stream comprising hydrocarbons, carbon monoxide, and nitrogen oxides.