Outlet-Coated Ceramic Honeycomb for SCR Backpressure Reduction
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Solution Overview
Problem
Conventional ceramic honeycomb filters face issues with increased backpressure and reduced soot and ash storage capacity due to the distribution of selective catalyst reduction (SCR) catalyst on filtration walls, which also limits passive regeneration of soot.
Innovation Solution
A coated ceramic honeycomb body with a honeycomb structure featuring intersecting porous walls, where outlet channels have a greater surface area than inlet channels, and the SCR catalyst is preferentially located on non-filtration walls within the outlet channels, reducing catalyst loading on filtration walls and enhancing passive regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SCR catalyst is distributed on filtration walls, then catalytic efficiency is improved, but backpressure increases and soot storage capacity decreases
Solution Approach 1:
The patent segments the honeycomb structure into filtration walls and non-filtration walls. The SCR catalyst is selectively applied only to non-filtration walls, separating the filtration function from the catalytic function. This segmentation allows the filtration walls to remain free of catalyst, maintaining low backpressure and high soot storage capacity, while non-filtration walls provide the necessary catalytic activity for NOx reduction.
Solution Approach 2:
The patent applies local quality by creating non-uniform catalyst distribution across different wall types. Non-filtration walls are selectively coated with SCR catalyst, while filtration walls remain uncoated. This localized application ensures that catalytic efficiency is achieved in regions where it is needed (non-filtration walls) without compromising the filtration performance and flow characteristics (filtration walls).
2Reliability
If SCR catalyst is distributed on filtration walls, then catalytic efficiency is improved, but soot and ash storage capacity decreases
Solution Approach 1:
The patent segments the honeycomb structure into filtration walls and non-filtration walls. The SCR catalyst is selectively applied only to non-filtration walls, separating the filtration function from the catalytic function. This segmentation allows the filtration walls to remain free of catalyst, maintaining high soot storage capacity, while non-filtration walls provide the necessary catalytic activity for NOx reduction.
Solution Approach 2:
The patent applies local quality by creating non-uniform catalyst distribution across different wall types. Non-filtration walls are selectively coated with SCR catalyst, while filtration walls remain uncoated. This localized application ensures that catalytic efficiency is achieved in regions where it is needed (non-filtration walls) without compromising the filtration performance and flow characteristics (filtration walls).
3Reliability
If SCR catalyst is distributed on filtration walls, then catalytic efficiency is improved, but passive regeneration of soot is limited
Solution Approach 1:
The patent segments the honeycomb structure into filtration walls and non-filtration walls. The SCR catalyst is selectively applied only to non-filtration walls, separating the filtration function from the catalytic function. This segmentation allows the filtration walls to remain free of catalyst, enabling effective passive regeneration of soot, while non-filtration walls provide the necessary catalytic activity for NOx reduction.
Solution Approach 2:
The patent applies local quality by creating non-uniform catalyst distribution across different wall types. Non-filtration walls are selectively coated with SCR catalyst, while filtration walls remain uncoated. This localized application ensures that catalytic efficiency is achieved in regions where it is needed (non-filtration walls) without compromising the filtration performance and flow characteristics (filtration walls).
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 configuration reduces backpressure, improves catalytic efficiency for NOx reduction, and increases the soot regeneration capacity by minimizing catalyst interference with particulate matter in the inlet channels.
Implementation Method 1
The channels are end-plugged, such as to form a checkered pattern of plugs, at the inlet and outlet end faces. Channels having their ends plugged at the inlet end face and open at the outlet end face are referred to as outlet channels, and the channels having their ends plugged at an outlet end face and open at an inlet end face are referred to as inlet channels. In operation, exhaust gas or other particulate-laden flow enters the wall-flow honeycomb filter through the inlet channels, is forced from inlet channels into the outlet channels through adjoining porous walls, and exits through the outlet channels, with the porous walls acting as filtration walls retaining a portion of the particulates from the flow.
Implementation Method 2
The ceramic honeycomb body may be catalyzed to reduce pollutants such as Sox, Nox, hydrocarbons and/or carbon monoxide from the exhaust gas flow prior to the flow exiting the body. In particular, in some ceramic honeycombs, a selective catalyst reduction (SCR) catalyst can be applied as a component of a wash coat to the filtration walls.
Implementation Method 3
exhaust gas or other particulate-laden flow enters the wall-flow honeycomb filter through the inlet channels, is forced from inlet channels into the outlet channels through adjoining porous walls
Data Source
AI summary
A coated ceramic honeycomb body comprising a honeycomb structure comprising a matrix of intersecting porous walls forming a plurality of axially-extending channels, at least some of the plurality of axially-extending channels being plugged to form inlet channels and outlet channels, wherein a total surface area of the outlet channels is greater than a total surface area of the inlet channels, and wherein a catalyst is preferentially located within the outlet channels, and preferentially disposed on non-filtration walls of the outlet channels. Methods and apparatus configured to preferentially apply a catalyst-containing slurry to the outlet channels and non-filtration walls are provided, as are other aspects.