Zone Coated Filter for Diesel Exhaust
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Solution Overview
Problem
Current diesel exhaust treatment systems face challenges with high material costs and degradation of catalysts due to exposure to high temperatures, particularly in particulate filter systems that use platinum group metal-containing compositions.
Innovation Solution
The integration of a light-off oxidation catalyst directly onto the particulate filter, combined with a NOx reducing catalyst downstream, allows for active regeneration of the filter at lower temperatures, reducing the need for a separate light-off catalyst and minimizing exposure to high temperatures, thus conserving precious metal usage and improving system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a separate light-off oxidation catalyst is used upstream of the particulate filter, then the filter can be regenerated at lower temperatures, but the system complexity and material costs increase due to additional platinum group metal usage
Solution Approach 1:
The patent combines the light-off oxidation catalyst and particulate filter into a single integrated component. The oxidation catalyst is disposed on the inlet end of the particulate filter substrate, eliminating the need for a separate upstream light-off catalyst. This merging reduces system complexity and platinum group metal usage while maintaining the ability to regenerate the filter at lower temperatures.
Solution Approach 2:
The integrated component serves multiple functions: the oxidation catalyst portion performs fuel light-off and exotherm generation, while the particulate filter portion captures and regenerates particulate matter. This multi-functionality eliminates the need for separate dedicated components for each function.
2Temperature
If platinum group metal-containing compositions are used in particulate filter systems, then active regeneration at lower temperatures is achieved, but material costs and catalyst degradation increase due to exposure to high temperatures
Solution Approach 1:
The oxidation catalyst is applied only to the inlet end zone of the particulate filter substrate, creating a localized catalytic region. This zoned approach concentrates the platinum group metals where they are most needed for light-off and exotherm generation, while the remainder of the filter substrate can use less expensive materials or lower catalyst loadings, reducing overall material costs and degradation risk.
Solution Approach 2:
The patent utilizes the exothermic reaction from fuel combustion on the oxidation catalyst to generate the high temperatures needed for particulate regeneration. This converts the potentially harmful effect of high temperatures (which cause catalyst degradation) into a beneficial self-heating mechanism that enables regeneration without requiring external heating sources.
3Temperature
If a separate light-off oxidation catalyst is disposed upstream of the particulate filter, then lower regeneration temperatures are achieved, but the quantity of precious metals required increases
Solution Approach 1:
By merging the light-off oxidation catalyst and particulate filter into a single integrated component, the patent eliminates the need for separate platinum group metal loadings in both components. The oxidation catalyst portion uses platinum group metals for light-off, while the particulate filter portion can use base metals or lower catalyst loadings, significantly reducing total precious metal consumption.
Solution Approach 2:
The oxidation catalyst is applied only to the inlet end zone of the particulate filter substrate, creating a localized catalytic region. This zoned approach concentrates the platinum group metals where they are most needed for light-off and exotherm generation, while the remainder of the filter substrate can use less expensive materials or lower catalyst loadings, reducing overall material costs and degradation risk.
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
This approach reduces material costs, minimizes catalyst degradation, and enhances the overall performance of the NOx reduction components by allowing higher operating temperatures and more efficient heat distribution within the system.
Implementation Method 1
oxidation catalysts... facilitate the treatment of diesel engine exhaust by promoting the conversion of both unburned hydrocarbons (HC) and carbon monoxide (CO) gaseous pollutants, and some proportion of the particulate matter through oxidation of these pollutants to carbon dioxide and water
Implementation Method 2
Certain oxidation catalysts also promote the oxidation of NO to NO2
Implementation Method 3
light off fuel at a temperature of less than about 300° C. and to produce an exotherm sufficient to burn off trapped particulate in the filter
Implementation Method 4
elements for trapping particulate contained in an exhaust stream flowing through the filter
Data Source
AI summary
Exhaust treatment filters, systems, and methods are disclosed. According to one or more embodiments, a particulate filter is zone coated with an oxidation catalyst and is used in an emission treatment system or method including a NOx reducing catalyst and an optional NH3 destruction catalyst.