Platinum Catalyst Degreening for Stable NO2 Production
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Solution Overview
Problem
Diesel engine catalysts, such as DOCs and CSF catalysts, experience degreening issues, leading to unstable NO2/NOx ratios, which affect downstream SCR catalyst performance due to the need for reductant-rich conditions and temperature variability during engine operation.
Innovation Solution
Producing fully degreened diesel oxidation catalysts by treating platinum-based catalysts at temperatures greater than or equal to 500°C in humidified air, resulting in a stable peak vibration frequency of 2085-2105 cm−1, ensuring consistent NO2 production and maintaining catalyst performance over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional calcination in air at 450-500°C is used, then the catalyst is easier to manufacture, but the catalyst experiences degreening during use leading to unstable NO2/NOx ratio
Solution Approach 1:
The patent applies preliminary action by performing degreening treatment during the catalyst manufacturing process itself, rather than waiting for the catalyst to degreen during vehicle operation. The catalyst is treated in humidified air at temperatures of 500°C or higher during production, which transforms the platinum surface configuration in advance. This ensures the catalyst starts in a fully degreened state with stable NO2/NOx ratio, eliminating the need for prolonged vehicle operation to achieve stability.
2Reliability
If high temperature treatment (≥500°C) in humidified air is applied during production, then the catalyst achieves full degreening and stable performance, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies parameter changes by modifying the calcination conditions during manufacturing: using humidified air instead of dry air, and increasing the temperature to 500°C or higher. These parameter changes transform the platinum surface configuration and oxidation state during production, achieving full degreening in advance. The humidified air environment facilitates the formation of the desired platinum surface configuration, while the higher temperature ensures complete transformation, resulting in a catalyst that is fully active and stable from the outset.
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
This method allows for the production of catalysts that are fully active and stable from the outset, providing a consistent NO2 conversion and improving the performance of downstream SCR catalysts by maintaining a stable NO2/NOx ratio, thus enhancing NOx conversion efficiency.
Implementation Method 1
platinum-based or platinum-palladium-based and are used to accelerate NO oxidation, generating NO2
Implementation Method 2
by replacing traditional calcination in air in a calcination furnace at temperatures in the range of 450-500°C with treatment conditions of temperatures greater than or equal to about 500°C in humidified air
Data Source
AI summary
Emissions treatment systems of combustion engines are provided, which comprise a platinum-containing catalyst that is degreened during production, which is before exposure to operating conditions of a vehicle having a diesel engine. The platinum-containing catalyst, in the form of a platinum component on a high surface area refractory metal oxide support, exhibits a vibration frequency of about 2085 to about 2105 cm−1 as measured by CO-DRIFTS. Such catalytic material is essentially-free of platinum oxide species found at greater than about 2110 cm−1 as measured by CO-DRIFTS. Such catalysts can provide excellent and consistent conversion of nitrogen oxide (NO) to nitrogen dioxide (NO2).