Honeycomb Filter Catalyst Coating for Pressure Loss
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Solution Overview
Problem
Conventional catalyst loading filters face challenges in achieving high soot burning speed while minimizing pressure loss, especially during high-load high-speed engine operation, due to the permeability issues caused by catalyst coatings with smaller pore diameters, which also affect regeneration efficiency and NOx catalyst durability.
Innovation Solution
A honeycomb filter design where partition walls have PM collection layers with smaller pore diameters than the partition walls, coated with a catalyst only in specific regions, avoiding the surface of the PM collection layers to reduce pressure loss and enhance regeneration efficiency, with NOx removing catalysts on the partition walls to prevent ash and sulfur contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the partition walls are coated with a catalyst layer having smaller pore diameters to collect particulates, then the particulate collection efficiency is improved, but the permeability decreases and pressure loss increases
Solution Approach 1:
The patent applies different catalyst coating densities to different regions of the partition wall. The inlet side (upstream) has a lower catalyst coating density to maintain permeability and reduce pressure loss, while the outlet side (downstream) has a higher catalyst coating density to enhance soot burning efficiency. This local differentiation resolves the contradiction between particulate collection and pressure loss.
Solution Approach 2:
The partition wall is divided into multiple regions with different catalyst coating characteristics. The inlet region uses a first catalyst coating with lower density, while the outlet region uses a second catalyst coating with higher density. This segmentation allows each region to optimize for its specific function, reducing overall pressure loss while maintaining soot burning capability.
2Productivity
If the catalyst layer with smaller pore diameters is used to promote soot oxidation, then the regeneration efficiency is improved, but the soot burning speed at high flow rates decreases
Solution Approach 1:
The patent creates different catalyst environments in different regions. The inlet region provides a more open structure for exhaust gas flow and soot transport, while the outlet region provides a denser catalyst environment for efficient soot burning. This local differentiation enables both high soot burning speed and good regeneration efficiency.
Solution Approach 2:
The partition wall is segmented into inlet and outlet regions with different catalyst properties. The inlet region facilitates soot transport to the catalyst, while the outlet region provides the catalyst environment for complete oxidation. This segmentation resolves the contradiction between regeneration efficiency and soot burning speed.
3Object-generated harmful factors
If the entire surface of PM collection layers is coated with catalyst to maximize purification, then the exhaust gas purification is improved, but the pressure loss increases due to reduced permeability
Solution Approach 1:
The patent applies catalyst coating selectively rather than uniformly across the entire partition wall surface. The inlet side has reduced catalyst coating to maintain permeability, while the outlet side has full or enhanced coating for purification. This local quality approach achieves exhaust gas purification without excessive pressure loss.
Solution Approach 2:
The partition wall surface is segmented into inlet and outlet regions with different catalyst coating coverage. The inlet region has minimal catalyst coating to preserve gas flow permeability, while the outlet region has full catalyst coating for maximum purification effect. This segmentation resolves the contradiction between purification and pressure loss.
4Manufacturing precision
If the catalyst layer is made with smaller pore diameters to trap particulates, then the particulate collection is improved, but the catalyst durability decreases due to ash and sulfur contact
Solution Approach 1:
The patent creates a protective effect by having the inlet region with lower catalyst density act as a filter that traps ash and sulfur particles before they reach the outlet region where the catalyst is located. This local differentiation protects the catalyst from deterioration while maintaining particulate collection efficiency.
Solution Approach 2:
The inlet region with its catalyst coating acts as an intermediary layer that captures harmful substances (ash and sulfur) from the exhaust gas, preventing them from reaching and deteriorating the main catalyst in the outlet region. This intermediary function protects catalyst durability while maintaining collection efficiency.
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 design enables high soot burning speed at low temperatures through NO2 back diffusion, maintains low pressure loss, and increases NOx purification efficiency while protecting the NOx catalyst from deterioration.
Implementation Method 1
the oxidizing catalyst loaded in the surfaces of the partition walls of the honeycomb filter and the inner surfaces of the pores present in the partition walls promotes the oxidation (the burning) of the particulates
Implementation Method 2
a gas G 1 flows into the partition wall from the openings 109 of the pores and is discharged to the adjacent cell as the through channel from openings 115 of pores formed on an outlet side 113 of the partition wall
Implementation Method 3
This design enables high soot burning speed at low temperatures through NO2 back diffusion
Data Source
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AI summary
There is disclosed a honeycomb filter in which partition walls are provided with PM collection layers having a small average pore diameter, and coated with a catalyst, whereby a regeneration efficiency is increased. The honeycomb filter has a constitution of a catalyst loading filter made of a base material of a honeycomb structure including a plurality of cells as through channels of an exhaust gas which are partitioned by partition walls made of a porous ceramic material having a large number of pores 5, and the filter includes plugging portions which alternately plug one opening end and the other opening end of each of the plurality of cells. Partition walls 4 are provided with PM collection layers 20 having a smaller average pore diameter than that of the partition walls, and the partition walls are coated with a catalyst 15 without coating a portion including a surface of the PM collection layer 20 with the catalyst.