Ternary Platinum Alloy Catalysts for Hydrothermal Aging Stability
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Solution Overview
Problem
Existing oxidation catalysts for internal combustion engines suffer from reduced activity and stability due to hydrothermal aging, leading to decreased NO2 generation and complexity in calibrating urea injection rates, particularly at lower temperatures, and are prone to sintering which affects catalytic performance.
Innovation Solution
A ternary alloy nanoparticle catalyst comprising platinum group metals alloyed with at least two transition metal elements, supported on refractory oxides, is developed to enhance CO, HC, and NO→NO2 oxidation stability and efficiency, with specific atomic ratios and preparation processes to maintain catalytic performance under hydrothermal aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If platinum group metals are dispersed on refractory metal oxide support for oxidation catalysis, then CO and HC conversion is improved, but catalyst activity decreases after hydrothermal aging
Solution Approach 1:
The patent employs a composite material structure consisting of platinum group metals dispersed on refractory metal oxide support. This composite architecture combines the high catalytic activity of PGMs with the thermal stability of refractory oxides, enabling the catalyst to maintain both CO/HC conversion efficiency and activity stability after hydrothermal aging.
2Productivity
If platinum group metals promote NO oxidation to NO2, then downstream SCR activity is enhanced, but NO2 generation decreases after aging
Solution Approach 1:
The refractory metal oxide support in the composite structure provides thermal stability that prevents sintering of platinum group metal particles during aging. This maintains the dispersed state and active surface area of PGMs, ensuring consistent NO oxidation activity and NO2 generation both before and after hydrothermal aging.
3Productivity
If catalyst is exposed to high temperatures, then oxidation catalysis is enhanced, but sintering of catalytic component occurs
Solution Approach 1:
The refractory metal oxide support acts as a thermally stable matrix that anchors platinum group metal particles, preventing their coalescence and crystallite growth at high temperatures. The strong interaction between PGMs and the refractory oxide surface maintains particle dispersion and prevents sintering even under prolonged high-temperature exposure.
4Productivity
If catalyst is exposed to high temperatures, then oxidation reactions are promoted, but carrier pore structure is lost
Solution Approach 1:
The refractory metal oxide support provides localized thermal stability at the carrier level, protecting the pore structure from collapse during high-temperature operation. The refractory oxide's high melting point and structural rigidity maintain the carrier's porous architecture, ensuring continued accessibility to catalytic active sites even after exposure to elevated temperatures.
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 ternary alloy nanoparticle catalyst maintains high NO2/NOx ratios and improves CO and HC conversion, demonstrating enhanced stability and catalytic performance even after hydrothermal aging, thus optimizing exhaust gas treatment.
Implementation Method 1
oxidation catalysts comprising a precious metal, such as platinum group metals (PGMs), dispersed on a refractory metal oxide support, such as alumina, are used in treating the exhaust of internal combustion engines in order to convert both HC and CO gaseous pollutants by catalyzing the oxidation of these pollutants to carbon dioxide and water
Implementation Method 2
oxidation catalysts comprising a precious metal dispersed on a refractory metal oxide support are known for use in treating the exhaust of diesel engines
Data Source
AI summary
Disclosed herein are oxidation catalysts, oxidation catalyst composites, systems, and methods for treating exhaust gas streams to control the emission of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) in the exhaust gas stream of internal combustion engines. The oxidation catalysts, oxidation catalyst composites, systems and methods of treating comprise a ternary alloy nanoparticle catalyst; the ternary alloy nanoparticle catalyst comprises a platinum group metal alloyed with at least two transition metal elements.