Zoned Catalyzed Filter Substrate for Exhaust Emission Control
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Solution Overview
Problem
Current exhaust systems for internal combustion engines are inadequate in effectively reducing NOx, NH3, and H2S emissions, as well as oxidizing hydrocarbons and carbon monoxide, due to limitations in NOx trap efficiency and desulfation processes.
Innovation Solution
A catalysed exhaust system comprising a lean NOx trap with an oxidation/reduction catalyst and a catalysed filter substrate with distinct zones, where the first zone contains platinum group metals and the second zone includes copper or iron loaded on a zeolite, performing multiple functions including NOx storage, ammonia utilization, H2S control, and soot removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lean NOx trap is used to store NOx and perform oxidation/reduction, then NOx conversion is improved, but ammonia and hydrogen sulfide emissions are not sufficiently reduced
Solution Approach 1:
The catalytic substrate is divided into multiple zones with different catalytic functions. The first zone contains platinum group metals for oxidation reactions, while the second zone contains copper or iron on zeolite for ammonia storage and H2S removal, allowing simultaneous处理 of multiple pollutants without interference
Solution Approach 2:
The catalytic substrate integrates multiple functions into a single component: oxidation of hydrocarbons and CO, ammonia storage, H2S removal, and soot oxidation. This multi-functional design eliminates the need for separate devices for each function while improving overall emission control efficiency
2Reliability
If desulfation processes are applied to remove sulfate from the NOx trap, then sulfur accumulation is reduced, but hydrogen sulfide emissions increase
Solution Approach 1:
The second zone of the catalytic substrate acts as an intermediary component that captures H2S released during desulfation of the NOx trap. The copper or iron on zeolite in this zone specifically adsorbs H2S, preventing it from being emitted while allowing the desulfation process to continue effectively
3Reliability
If multiple separate catalysts are used for different functions, then each function can be optimized, but system complexity increases
Solution Approach 1:
Multiple catalytic functions that would traditionally require separate catalysts and substrates are merged into a single catalytic substrate with multiple zones. Each zone contains different catalytic materials optimized for specific functions, but all functions are integrated in one component, reducing system complexity while maintaining treatment effectiveness
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 system enhances NOx conversion, reduces ammonia and hydrogen sulfide emissions, optimizes NOx conversion, and effectively oxidizes hydrocarbons and carbon monoxide, while minimizing soot and hydrogen sulfide production, thereby improving overall exhaust gas treatment efficiency.
Implementation Method 1
the first zone comprises a platinum group metal loaded on a support
Implementation Method 2
an oxidation catalyst to oxidize hydrocarbons that were not combusted in the internal combustion engine and to convert CO to CO2
Implementation Method 3
the second zone comprises copper or iron loaded on a zeolite
Implementation Method 4
The NH3-SCR catalyst is taught to adsorb the ammonia that is generated during the rich pulses in the lean NOx trap
Implementation Method 5
the first zone or the second zone additionally comprises a base metal oxide or a base metal loaded on an inorganic oxide
Implementation Method 6
an oxidation/reduction catalyst, wherein the oxidation/reduction catalyst comprises one or more of platinum, palladium, and/or rhodium
Implementation Method 7
a catalysed filter substrate having a first zone and a second zone
Implementation Method 8
a carbon soot filter to remove particulates from the exhaust gas before release to atmosphere
Data Source
AI summary
An exhaust system for internal combustion engines, and a catalyzed substrate for use in an exhaust system, is disclosed. The exhaust system comprises a lean NOx trap and the catalyzed substrate. The catalyzed substrate has a first zone and a second zone, wherein the first zone comprises a platinum group metal loaded on a support and the second zone comprises copper or iron loaded on a zeolite. The first zone or second zone additionally comprises a base metal oxide or a base metal loaded on an inorganic oxide. Also provided are methods for treating an exhaust gas from an internal combustion engine using the exhaust system. The exhaust system is capable of storing NH3 generated in rich purging, reacting the NH3 with slip NOx from the ??? trap, controlling H2S released from NOx trap desulfation, and oxidizing slip hydrocarbons and carbon monoxide. When the catalyzed substrate is a filter substrate, it is also capable of removing soot from exhaust system.