Diesel Oxidation Catalyst Capture Region for Impurity Trapping
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Solution Overview
Problem
Diesel engine exhaust systems face degradation due to phosphorus and sulfur containing impurities, which accumulate in emissions control devices like diesel oxidation catalysts (DOCs), leading to reduced performance and the need for frequent replacements.
Innovation Solution
An oxidation catalyst with a capture material, such as a molecular sieve, that traps phosphorus and sulfur containing impurities, preventing them from degrading the catalytic activity and extending the lifespan of the DOC by incorporating a platinum group metal (PGM) catalytic region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diesel oxidation catalyst is used to treat exhaust gas, then carbon monoxide and unburned hydrocarbons are oxidized, but phosphorus and sulfur impurities accumulate in the catalyst and degrade its performance
Solution Approach 1:
The catalyst is divided into distinct functional zones: a capture region containing molecular sieves for trapping phosphorus and sulfur impurities, and a catalytic region containing platinum group metals for oxidation reactions. This segmentation allows impurities to be captured before reaching the active catalytic sites, preventing degradation and extending catalyst lifetime while maintaining oxidation performance.
2Duration of action of stationary object
If the catalyst operates for extended periods to meet long lifetime requirements, then impurities have more time to accumulate and poison catalytic sites, but replacing the catalyst frequently increases maintenance costs
Solution Approach 1:
The molecular sieve capture material is positioned upstream in the catalyst structure to preemptively trap phosphorus and sulfur impurities before they can reach and poison the platinum group metal catalytic sites. This preliminary action of impurity capture preserves catalytic activity over extended operation periods, enabling longer catalyst lifetime without performance degradation.
3Reliability
If impurities are allowed to accumulate in the catalyst, then the catalyst structure becomes saturated and downstream emissions control devices are poisoned, but capturing impurities requires additional capture materials
Solution Approach 1:
The invention merges the impurity capture function and the catalytic oxidation function into a single integrated catalyst structure. The molecular sieve capture material and platinum group metal catalytic material are combined in one catalyst assembly, with the capture region protecting the catalytic region. This integration eliminates the need for separate downstream protection devices while maintaining performance.
Solution Approach 2:
The molecular sieve material acts as an intermediary between the exhaust gas stream and the platinum group metal catalytic sites. It selectively traps phosphorus and sulfur impurities, preventing them from directly interacting with and poisoning the catalytic sites, thereby protecting downstream device performance while maintaining a relatively simple catalyst structure.
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 effectively maintains oxidative activity and prevents impurity-induced degradation, ensuring consistent performance and extending the lifespan of emissions control devices, thereby reducing replacement frequencies.
Implementation Method 1
a capture material for capturing at least one phosphorus containing impurity and/or at least one sulfur containing impurity in the exhaust gas produced by the diesel engine
Implementation Method 2
a catalytic region disposed on the substrate, wherein the catalytic region comprises a catalytic material comprising a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd) and a combination of platinum (Pt) and palladium (Pd)
Data Source
AI summary
An oxidation catalyst is described for treating an exhaust gas produced by a diesel engine, wherein the oxidation catalyst comprises: a substrate; a capture material for capturing at least one phosphorus containing impurity and/or at least one sulfur containing impurity in the exhaust gas produced by the diesel engine; and a catalytic region disposed on the substrate; wherein the catalytic region comprises a catalytic material comprising a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd) and a combination of platinum (Pt) and palladium (Pd).