Platinum Catalyst for Stable NO Oxidation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catalyst compositions for compression ignition engines suffer from variability in NO2 generation over their lifetime, affecting the performance of downstream emissions control devices and making calibration of nitrogenous reductants challenging.
Innovation Solution
A catalyst composition comprising platinum supported on a refractory metal oxide, where the platinum is reduced with a reducing agent and heated to at least 650°C, stabilizing NO2 generation activity and maintaining high NO oxidation activity throughout the catalyst's lifecycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxidation catalyst is used to generate NO2 in an exhaust system, then the performance of downstream emissions control devices is improved, but the amount of NO2 generated varies considerably over the catalyst's lifetime, compromising downstream device performance
Solution Approach 1:
The patent applies parameter changes by modifying the heating temperature parameter to at least 650°C during catalyst preparation, and by controlling the reduction step with a reducing agent. These parameter changes stabilize the platinum crystallite structure, preventing sintering and maintaining consistent NO2 generation activity throughout the catalyst's lifetime, thus resolving the contradiction between reliability and stability.
2Adaptability or versatility
If an oxidation catalyst generates variable amounts of NO2 over its lifetime, then downstream catalyst formulation must be adjusted to accommodate variation, but this increases system complexity and calibration difficulty
Solution Approach 1:
The patent applies preliminary action by stabilizing the catalyst's NO2 generation capability during the manufacturing process through controlled reduction and high-temperature heating. This preliminary stabilization eliminates the need for downstream catalyst formulation adjustments and simplifies system configuration, resolving the contradiction between adaptability and device complexity.
3Reliability
If an oxidation catalyst is positioned upstream of an SCR catalyst to improve NO2 ratio, then SCR catalyst performance is enhanced, but variation in NO2 generation makes reductant dosing calibration difficult
Solution Approach 1:
The patent applies parameter changes by controlling the heating temperature to at least 650°C and managing the reduction step, which stabilizes the platinum crystallite size and structure. This ensures consistent NO2 generation ratios, enabling precise reductant dosing calibration for SCR systems while maintaining enhanced SCR catalyst performance, thus resolving the contradiction between reliability and manufacturing precision.
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 solution ensures a stable ratio of NO2 to NOx, minimizing changes in NO2 generation over time, thus simplifying the calibration of nitrogenous reductants and maintaining optimal performance of downstream emissions control devices.
Implementation Method 1
preparing a second composition by reducing the platinum (Pt) compound to platinum (Pt) with a reducing agent
Implementation Method 2
heating the second composition to at least 650°C
Implementation Method 3
Oxidation catalysts, such as DOCs, can oxidise some of the nitric oxide (NO) in an exhaust gas to nitrogen dioxide (NO2)
Implementation Method 4
oxidising CO and HCs and (ii) a selective catalytic reduction (SCR) catalyst for reducing NOx to nitrogen (N2)
Data Source
AI summary
A method of preparing a catalyst composition for producing a stable ratio of NO2 to NO in an exhaust system of a compression ignition engine is described. The method comprises: (i) preparing a first composition comprising a platinum (Pt) compound disposed or supported on a support material; (ii) preparing a second composition by reducing the platinum (Pt) compound to platinum (Pt) with a reducing agent; and (iii) heating the second composition to at least 650° C.