Catalytic Particulate Filter Coating for NOx Purification
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Solution Overview
Problem
The accumulation of soot and smoke in catalytic particulate filters reduces the NO2 generation and NOx purification efficiency of selective catalyst reduction devices, as the trapped particulate materials increase flow resistance and reduce the effectiveness of catalysts.
Innovation Solution
A catalytic particulate filter with a first coating layer on the interior surface from the inlet to a predetermined length and a second coating layer on the exterior surface from the outlet to a predetermined length, where the catalyst is not coated on the interior surface downstream, combined with a third coating layer on the plug surface, connected to the second coating layer, to maintain NO2 generation and enhance NOx purification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the catalytic particulate filter is used to trap and accumulate soot, then particulate materials are filtered, but the generating amount of NO2 is reduced and NOx purification efficiency is reduced
Solution Approach 1:
The filter is divided into multiple channels with alternating closed and open inlets, creating separate flow paths. This segmentation allows exhaust gas to follow a zigzag path through the filter structure, ensuring continuous contact with catalyst coating layers while maintaining particulate filtration capability.
Solution Approach 2:
The catalyst coating is extended from the interior surface to the exterior surface of the channel walls, adding a dimensional aspect to the catalytic action. This multi-surface coating approach increases the effective catalytic contact area and maintains NO2 generation even when soot accumulates in the channel interiors.
2Productivity
If soot is trapped and accumulated inside the catalytic particulate filter, then particulate filtration is achieved, but the NO2 generation amount is reduced
Solution Approach 1:
Catalyst coating layers are pre-applied to both interior and exterior surfaces of the channel walls before soot accumulation occurs. This preliminary catalytic preparation ensures that when exhaust gas flows through the filter, it encounters active catalyst surfaces immediately, maintaining NO2 generation capability throughout the filter's operational life.
Solution Approach 2:
Different regions of the filter structure are given different qualities: the interior surfaces are designed for soot trapping, while the exterior surfaces are coated with catalyst for NO2 generation. This local differentiation allows simultaneous optimization of both filtration and catalytic functions without mutual interference.
3Reliability
If the catalyst is coated on the interior surface of the channel, then catalytic purification occurs, but the catalyst deteriorates due to soot accumulation
Solution Approach 1:
The exterior surface of the channel wall acts as an intermediary catalytic surface that is not directly exposed to soot accumulation in the channel interior. By placing catalyst coating on this intermediary surface, the system maintains catalytic activity without the catalyst being contaminated by trapped particulate materials.
Solution Approach 2:
Instead of coating the catalyst only on the interior surface where soot accumulates, the invention inverts the approach by coating the exterior surface where soot does not accumulate. This reversal protects the catalyst from deterioration while maintaining its purification function.
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 improved coating structure sustains NO2 generation and increases NOx purification efficiency by up to 15% even with soot accumulation, by elongating contact time with catalyst layers and preventing catalyst deterioration.
Implementation Method 1
a first coating layer of which a catalyst is coated to be formed on an interior surface of the channel... a second coating layer of which the catalyst is coated to be formed on an exterior surface of the channel... the catalyst is not coated on an interior surface of a downstream side of the channel
Data Source
AI summary
An exhaust gas purification device that includes a catalytic particulate filter having at least an exhaust gas channel, the exhaust gas channel may include a first channel and a second channel being laterally coupled each other and fluidly communicating therebetween, wherein the exhaust gas is inlet through inlet opening of the first channel and outlet through lower portion of the first channel and/or outlet opening of the second channel, and wherein a first coating layer is formed on an interior surface of the first channel in a longitudinal direction thereof substantially from the inlet opening in a first predetermined length, the first coating layer being coated with a catalyst, and a second coating layer is formed on an interior surface of the second channel in a longitudinal direction thereof substantially from the outlet opening in a second predetermined length, the second coating layer being coated with the catalyst and a third coating is formed on an outside surface of a plug closing the outlet end of the first channel such that the second and third coating layers are connected.