Multi-Component Wall-Flow Filter for Diesel Emissions
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Solution Overview
Problem
Current exhaust treatment systems for lean burn engines, such as diesel engines, are inefficient in removing soot, ammonia, NOx, CO, and hydrocarbons while being costly and space-consuming due to the need for multiple catalysts and filters.
Innovation Solution
A catalytic article with a wall-flow filter coated with hydrolysis, selective catalytic reduction, ammonia oxidation, and oxidation catalysts, which traps soot and converts NOx and CO to harmless substances, reducing system complexity and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate catalysts and filters are used to treat diesel exhaust emissions, then the removal efficiency of various contaminants (soot, NOx, CO, hydrocarbons) is improved, but the system size, complexity, and cost increase significantly
Solution Approach 1:
The patent combines multiple separate emission control components (diesel oxidation catalyst, soot filter, SCR catalyst for NOx reduction) into a single integrated wall-flow filter structure. The filter walls contain multiple catalyst layers that perform different functions: soot trapping in the filter pores, NOx reduction via SCR reactions, and oxidation of CO and hydrocarbons. This merging eliminates the need for multiple separate components while maintaining comprehensive emissions control.
Solution Approach 2:
The wall-flow filter is designed as a multi-functional component that simultaneously performs filtration (soot trapping), catalytic reduction (NOx to N2), and catalytic oxidation (CO and hydrocarbons to CO2 and H2O). The different catalyst layers within the filter walls enable it to handle multiple types of emissions in a single device, making it a universal solution for diesel exhaust treatment.
2Reliability
If multiple separate catalysts and filters are used to treat diesel exhaust emissions, then the removal efficiency of various contaminants is improved, but the system cost increases
Solution Approach 1:
By merging multiple separate catalysts and filters into a single wall-flow filter assembly, the patent reduces the total number of components that need to be manufactured, installed, and maintained. This integration lowers material costs, assembly costs, and installation complexity while maintaining comprehensive emissions control functionality.
3Reliability
If multiple separate catalysts and filters are used to treat diesel exhaust emissions, then the removal efficiency of various contaminants is improved, but the system size increases
Solution Approach 1:
The integration of multiple emission control functions into a single wall-flow filter reduces the overall system volume by eliminating the space required for multiple separate components and their interconnections. The compact monolithic structure provides comprehensive emissions control in a smaller package compared to traditional multi-component systems.
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 catalytic article effectively filters soot and converts NOx and CO to nitrogen and CO2, improving emissions treatment efficiency without increasing system size or complexity, while promoting the oxidation of ammonia and hydrocarbons.
Implementation Method 1
a hydrolysis catalyst that promotes the hydrolysis of the ammonia precursor, the hydrolysis catalyst coated on a portion of the inlet walls of the inlet channels extending from the inlet end
Implementation Method 2
a selective catalytic reduction catalyst permeating the gas permeable walls, the selective catalytic reduction catalyst promoting the conversion of NOx in the gas stream to N2 in the presence of excess oxygen
Implementation Method 3
an ammonia oxidation catalyst that coats a length of the outlet walls of the outlet channels to promote the selective oxidation of ammonia to N2 in the gas stream
Implementation Method 4
an oxidation catalyst that coats a portion of the outlet walls of the outlet channels extending from the outlet end toward the inlet end to promote the oxidation of CO and hydrocarbons to CO2
Implementation Method 5
a wall-flow filter for trapping soot in the gas stream, the filter having an inlet end and an outlet end defining an overall length, gas permeable walls having a thickness formed into a plurality of axially extending inlet channels and outlet channels
Data Source
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AI summary
Catalytic articles, systems and methods for treating exhaust gas streams are described. A catalytic article comprising a wall flow filter having gas permeable walls, a hydrolysis catalyst, an optional soot oxidation catalyst, a selective catalytic reduction catalyst permeating the walls, an ammonia oxidation catalyst and an oxidation catalyst to oxidize CO and hydrocarbons is described. Methods of treating exhaust gas streams comprising soot, an ammonia precursor such as urea, ammonia, NOx, CO and hydrocarbons are also provided.