Yttrium-Doped Catalyst Support for Stable Low-Temperature NO Oxidation
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Solution Overview
Problem
Existing diesel oxidation catalysts suffer from significant loss of NO oxidation activity due to Pt particle agglomeration under high temperature conditions, and there is a need for catalysts that maintain effective HC, NOx, and CO conversion over extended periods, especially at low temperatures, to meet stringent emissions regulations.
Innovation Solution
A catalyst composition comprising platinum, manganese-doped refractory metal oxide support, and a metal component such as yttrium, which stabilizes platinum against sintering and enhances low-temperature NO2/NOx performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Pt-based DOCs are used, then NO oxidation activity is initially high, but significant loss of NO oxidation activity occurs upon aging due to Pt particle agglomeration
Solution Approach 1:
A manganese-doped alumina support material is introduced as an intermediary between the Pt particles and the environment. The manganese component (0.1-10 wt%) modifies the support properties to prevent Pt particle agglomeration, thereby maintaining NO oxidation activity during aging. The support acts as a mediator that stabilizes Pt particles without requiring additional stabilizing agents.
Solution Approach 2:
The invention changes the chemical composition parameters of the support material by doping alumina with manganese at specific concentrations (0.1-10 wt%). This parameter modification alters the surface properties and interaction characteristics of the support, enabling it to prevent Pt particle sintering and maintain catalytic activity under high-temperature aging conditions.
2Productivity
If Pt particles are used for NO oxidation, then catalytic efficiency is high at elevated temperatures, but activity is insufficient at low temperatures during cold start
Solution Approach 1:
The manganese doping concentration in the alumina support is optimized to enhance low-temperature NO oxidation activity. The specific amount of manganese (0.1-10 wt%) creates active sites that facilitate NO oxidation at temperatures below 250°C, while maintaining high-temperature performance through improved Pt particle stability.
3Productivity
If active regeneration is used to remove soot, then soot combustion is effective, but fuel economy penalty occurs due to additional diesel fuel injection
Solution Approach 1:
The invention utilizes NO2, a harmful emission component, as an oxidizing agent for soot combustion. The modified DOC promotes NO to NO2 conversion, and the manganese-doped support enables efficient soot oxidation by NO2 at lower temperatures (above 300°C), converting a harmful substance into a beneficial cleaning agent for the exhaust system.
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 catalyst composition maintains high catalytic efficiency and stability, promoting effective oxidation of NO to NO2 even at low temperatures, thus improving emissions control in diesel engines.
Implementation Method 1
oxidation catalysts comprising precious metals, such as platinum group metals (PGM) dispersed on a refractory metal oxide support, have been used to treat the exhaust of diesel engines by catalyzing the oxidation of hydrocarbon (HC) and carbon monoxide (CO) gaseous pollutants to carbon dioxide and water
Implementation Method 2
catalyzing the oxidation of hydrocarbon (HC) and carbon monoxide (CO) gaseous pollutants to carbon dioxide and water
Implementation Method 3
significant (often up to 50%) loss of NO oxidation activity is observed upon aging of conventional Pt-based DOCs, due at least in part to agglomeration of Pt particles
Data Source
AI summary
Disclosed herein are oxidation catalyst compositions comprising a first platinum group metal (PGM) component, a manganese (Mn) component, a first refractory metal oxide support material, and a metal component comprising yttrium, lanthanum, tin, magnesium, cerium, titanium, or a combination of any of the foregoing, wherein each of the first PGM component, the Mn component, and the metal component are supported on the first refractory metal oxide support material; catalyst articles coated with at least one such catalyst composition; and emission treatment systems including at least one such catalyst article.