WO3-TiO2 Catalyst Resists SOx Poisoning
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Solution Overview
Problem
Existing ammonia slip catalysts are susceptible to poisoning by sulfur oxides (SOx), which affects their performance in reducing NOx emissions in exhaust gases, especially in environments with high SOx concentrations.
Innovation Solution
A catalytic article featuring a noble metal on a WO3-TiO2 support with 1 to 20 weight percent WO3, which is resistant to SOx poisoning and effectively reduces ammonia slip when used downstream of a Selective Catalytic Reduction (SCR) process, allowing for improved NOx and ammonia oxidation in exhaust gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ammonia slip catalysts are used, then ammonia oxidation can occur, but the catalyst performance deteriorates due to SOx poisoning
Solution Approach 1:
The patent introduces a protective coating layer as an intermediary between the catalyst and the harmful SOx environment. This coating acts as a barrier that allows the catalyst to function while protecting it from sulfur poisoning, thereby maintaining long-term performance in high-SOx conditions
Solution Approach 2:
The patent modifies the catalyst's chemical or physical parameters through the protective coating, changing its interaction with SOx. The coating alters the surface properties to prevent sulfur adsorption while maintaining ammonia oxidation activity, effectively changing the catalyst's resistance parameters
2Reliability
If high-temperature regeneration is performed frequently to maintain catalyst activity, then catalyst performance is maintained, but fuel economy deteriorates
Solution Approach 1:
The protective coating is applied in advance to prevent sulfur accumulation before it deactivates the catalyst. This preliminary protective action eliminates the need for frequent high-temperature regenerations, reducing energy loss while maintaining catalyst activity
Solution Approach 2:
The patent converts the harmful SOx environment into a beneficial situation by using the protective coating to prevent sulfur poisoning. This allows the catalyst to operate continuously without frequent regenerations, transforming what would be a harmful condition into an opportunity for improved fuel economy
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 maintains high performance and resistance to SOx poisoning, reducing ammonia slip and NOx emissions over a broad operational temperature range, requiring less frequent high-temperature regenerations and improving fuel economy, even with high sulfur levels in the fuel.
Implementation Method 1
absorbing at least a portion of the SOx in the catalyst layer
Implementation Method 2
ammonia oxidation catalyst (AMOX) oxidizing excess ammonia
Implementation Method 3
wherein the catalyst layer adsorbs at least 5 g/L of the SOx
Data Source
Figure 1A~1B
Figure 2
AI summary
A catalyst article for treating an emission gas is provided comprising (a) an oxidation catalyst comprising at least one noble metal on a WO3-TiO2 support, wherein the support contains about 1 to about 20 weight percent WO3 based on the combined weight of the WO3 and TiO2; and (b) a substrate, wherein the first and second catalyst layers are on and/or within the substrate.