Dual Catalyst Diesel Filter for Soot Ignition and HC Storage
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Solution Overview
Problem
Current catalytically coated diesel particulate filters face challenges in achieving complete regeneration across all engine operating states due to limited sulfur tolerance of platinum/palladium coatings and require additional measures to reduce soot ignition temperature, leading to increased fuel consumption and complex regeneration processes.
Innovation Solution
A catalytically coated diesel particulate filter with a dual catalyst system, where the first catalyst contains platinum group metals and zeolites for hydrocarbon storage, and the second catalyst is applied over 5 to 80% of the filter length without zeolites, optimizing precious metal distribution and activity for efficient carbon monoxide and hydrocarbon conversion, while maintaining high thermal stability and reducing dynamic pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a catalytic coating with platinum and palladium is used to reduce soot ignition temperature, then the regeneration capability is improved, but the sulfur tolerance decreases leading to decreased catalytic activity
Solution Approach 1:
The filter is divided into two distinct catalytic zones: a first catalyst layer containing platinum group metals and zeolites applied over the entire filter length, and a second catalyst layer without zeolites applied only over 5-80% of the filter length. This segmentation allows different regions to perform different functions - the first layer provides hydrocarbon storage and catalytic activity, while the second layer provides oxidation capability without sulfur poisoning issues
Solution Approach 2:
Different catalytic compositions are applied to different portions of the filter. The first catalyst layer covering the entire length provides consistent hydrocarbon storage and catalytic activity, while the second catalyst layer applied only to a portion (5-80% of length) provides additional oxidation capability. This local differentiation optimizes both regeneration capability and sulfur tolerance in specific regions where needed
2Reliability
If additional catalytic measures are added to ensure complete regeneration across all engine operating states, then the regeneration reliability is improved, but the device complexity increases
Solution Approach 1:
The patent combines hydrocarbon storage functionality (via zeolites in the first catalyst layer) with catalytic oxidation capability (via platinum group metals in both layers) into a single integrated filter system. This merging eliminates the need for separate upstream oxidation catalytic converters and reduces the number of discrete components, while still achieving complete regeneration across all engine operating states
Solution Approach 2:
The first catalyst layer containing both zeolites and platinum group metals performs multiple functions: hydrocarbon storage, hydrocarbon oxidation, and contribution to soot ignition. The second catalyst layer provides additional oxidation capability. This multi-functionality reduces the need for separate dedicated components for each function, simplifying the overall system while ensuring complete regeneration
3Device complexity
If the filter is installed close to the engine to reduce installation space and costs, then the installation complexity is reduced, but the oxidation potential requirement increases
Solution Approach 1:
The first catalyst layer with zeolites performs preliminary hydrocarbon storage and oxidation before the exhaust gases reach the second catalyst layer. This preliminary action ensures that hydrocarbons are converted early in the process, providing the necessary oxidation potential for filters installed close to the engine where residence time and temperature may be limited
Solution Approach 2:
The catalyst layers use composite materials combining zeolites with platinum group metals on support materials. This composite structure provides both hydrocarbon storage capacity and high-temperature oxidation capability, enabling the filter to achieve sufficient oxidation potential even when installed close to the engine with reduced installation space
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 dual catalyst system enhances the filter's ability to convert hydrocarbons and carbon monoxide across various engine conditions, reducing emissions and fuel consumption, and improves the filter's aging stability and regeneration efficiency, even under low exhaust gas temperatures.
Implementation Method 1
The filter is coated along its entire length with a first catalyst (1) which contains platinum group metals on support materials as catalytic active components and which additionally contains at least one zeolite for storing hydrocarbons
Implementation Method 2
Through post-injection of additional fuel in combination with other engine measures (such as throttling), unburned fuel and carbon monoxide reach the diesel oxidation catalyst and are catalytically converted there to carbon dioxide and water
Implementation Method 3
The reaction heat released in the process heats up the exhaust gas and thus also the downstream particle filter
Implementation Method 4
The ignition temperature required to burn the soot particles is reduced by using catalytic converters
Data Source
AI summary
A diesel particle filter having an oxidation catalyst comprising platinum and palladium deposited thereon is described. The conversion of hydrocarbons and carbon monoxide can be significantly improved by mixing zeolites as HC storage components into the oxidation catalyst. Furthermore, the particle filter is coated with a second catalyst which does not contain any zeolites from the inlet end to part of the length.