Monolithic Wall-Flow Filter for Low-Temperature Exhaust Oxidation
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Solution Overview
Problem
Current exhaust gas treatment systems for internal combustion engines are complex and require multiple catalysts to effectively manage CO, HC, NOx, and particulate matter emissions, especially at low engine temperatures, leading to increased system complexity and backpressure.
Innovation Solution
A simplified exhaust gas treatment system incorporating a monolithic wall-flow filter catalytic article with a close-coupled configuration and a flow-through monolith catalytic article, featuring a selective catalytic reduction (SCR) coating composition and hydrogen injection, which combines diesel oxidation catalyst and catalyzed soot filter functions in a single article, reducing catalyst loading and backpressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple catalysts are used to effectively manage emissions at low engine temperatures, then emission treatment effectiveness is improved, but system complexity and backpressure increase
Solution Approach 1:
The patent combines multiple catalyst functions (diesel oxidation catalyst and catalyzed soot filter) into a single integrated monolithic wall-flow filter catalytic article. This merging reduces the number of separate components while maintaining effective emission treatment across multiple pollutant types including CO, HC, NOx, and particulate matter.
Solution Approach 2:
The integrated catalytic article performs multiple functions simultaneously: oxidation of CO and HC, reduction of NOx, and filtration of particulate matter. The SCR coating composition enables the system to handle diverse emissions across a wide temperature range, making the system universally effective for multiple emission control needs.
2Reliability
If multiple catalysts are used to effectively manage emissions, then emission treatment effectiveness is improved, but backpressure increases
Solution Approach 1:
By consolidating multiple catalyst functions into one monolithic wall-flow filter article, the patent reduces the cumulative backpressure that would result from multiple separate catalyst components. The integrated design maintains effective emission treatment while minimizing pressure losses in the exhaust system.
3Temperature
If a close-coupled configuration is used, then low temperature oxidation effectiveness is improved, but space requirements change
Solution Approach 1:
The close-coupled configuration places the catalytic article near the engine exhaust manifold, allowing the catalyst to receive hot exhaust gases early in the exhaust flow path. This preliminary exposure to high-temperature gases enables the catalyst to achieve effective oxidation at lower operating temperatures, improving cold-start performance.
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 achieves effective oxidation of NO, CO, and HC at low temperatures and reduces NOx emissions across a wide temperature range, while maintaining low backpressure and fuel efficiency, thereby simplifying the emission control process.
Implementation Method 1
oxidation catalyst compositions comprising a precious metal, such as platinum group metals (PGM), dispersed on a refractory metal oxide support, such as alumina, are known for use in treating the exhaust of diesel engines in order to convert both hydrocarbon and carbon monoxide gaseous pollutants by catalyzing the oxidation of these pollutants to carbon dioxide and water
Implementation Method 2
catalyzing the oxidation of these pollutants to carbon dioxide and water
Implementation Method 3
it is known in the art to include a sorbent material, which may be a zeolite, as part of a catalytic treatment system in order to adsorb and/or absorb gaseous pollutants, usually hydrocarbons, and retain them during the initial cold-start period
Implementation Method 4
include a sorbent material, which may be a zeolite, as part of a catalytic treatment system in order to adsorb and/or absorb gaseous pollutants
Implementation Method 5
a flow-through monolith catalytic article comprising a substrate having a selective catalytic reduction (SCR) coating composition disposed thereon
Implementation Method 6
selective catalytic reduction (SCR) coating composition
Implementation Method 7
oxidation catalysts that contain PGM promote the oxidation of NO to NO2
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
The disclosure provides a monolithic wall-flow filter catalytic article including a substrate having an aspect ratio of from about 1 to about 20, and having a functional coating composition disposed on the substrate, the functional coating composition including a first sorbent composition, an oxidation catalyst composition, and optionally, a second sorbent composition. The monolithic wall-flow filter catalytic article may be in a close-coupled position close to the engine. The disclosure further provides an integrated exhaust gas treatment system including the monolithic wall-flow filter catalytic article and may additionally include a flow-through monolith catalytic article. The flow-through monolith catalytic article includes a substrate having a selective catalytic reduction (SCR) coating composition disposed thereon. The integrated exhaust gas treatment system simplifies the traditional four-article system into a two-article Catalyzed Soot Filter (CSF) plus Selective Catalytic Reduction (SCR) CSF+SCR arrangement.