Honeycomb Structure with Oversized Pores for Catalyst Loading
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Solution Overview
Problem
Conventional honeycomb structures face challenges in carrying a large amount of catalyst while maintaining low pressure drop and ensuring structural integrity, as increased catalyst loading reduces cell channel sectional areas and increases pressure drop.
Innovation Solution
The development of a honeycomb structure with porous partition walls featuring pores larger than the wall thickness, occupying 4-11% of the total volume, and a manufacturing method that includes using a pore former with an average particle diameter larger than the wall thickness to create larger pores, which allows for a higher catalyst loading without significant pressure drop increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large amount of catalyst is deposited on the surfaces of partition walls, then the catalyst loading increases, but the pressure drop increases
Solution Approach 1:
The patent applies porous materials by forming pores within the partition walls themselves. These pores provide internal surface area for catalyst deposition, allowing the catalyst to be distributed both on the external surface and within the porous structure of the partition walls. This increases the effective catalyst loading without requiring additional external surface area, thereby avoiding the pressure drop increase that would result from reducing cell channel sectional areas.
Solution Approach 2:
The patent transitions from two-dimensional catalyst deposition (only on the external surface of partition walls) to three-dimensional catalyst distribution (within the porous structure and on the surface). By utilizing the internal volume of the partition walls through pore formation, the catalyst can be distributed in the third dimension, significantly increasing the catalyst loading capacity without occupying additional space in the cell channels that would restrict fluid flow.
2Quantity of substance
If the cell channel sectional areas are reduced to carry more catalyst, then the catalyst loading increases, but the pressure drop increases
Solution Approach 1:
The patent utilizes porous partition walls where the pores serve as additional spaces for catalyst deposition. This approach increases the catalyst loading capacity by utilizing the internal volume of the partition walls rather than reducing the cell channel cross-sectional areas. The pores provide internal surface area for catalyst distribution while maintaining the external cell channel dimensions necessary for adequate fluid flow and low pressure drop.
Solution Approach 2:
The invention moves catalyst deposition from a two-dimensional surface process to a three-dimensional volume utilization process. By forming pores within the partition walls, the catalyst can be distributed throughout the volume of the partition walls, not just on their external surfaces. This dimensional transition allows increased catalyst loading without compromising the cell channel sectional areas that determine pressure drop characteristics.
3Quantity of substance
If pores larger than wall thickness are formed, then the catalyst carrying capacity increases, but the manufacturing complexity increases
Solution Approach 1:
The patent employs pore formers as intermediary materials during the forming process. These pore formers are temporarily incorporated into the partition wall structure and are subsequently removed (typically by combustion or chemical treatment) to create the desired porous structure. This intermediary approach simplifies manufacturing by allowing pores of various sizes, including those larger than the wall thickness, to be formed through standard extrusion or molding processes followed by a simple removal step, rather than requiring complex post-processing to create large pores.
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 the honeycomb structure to carry a substantial amount of catalyst, such as SCR catalysts for NOx reduction, while maintaining a low pressure drop and enhanced structural strength, effectively balancing catalyst loading and pressure drop.
Implementation Method 1
using a pore former having an average particle diameter larger than a thickness of each of the partition walls of the obtained honeycomb structure... in the partition walls, it is possible to form remarkably large pores as compared with a conventional honeycomb structure
Implementation Method 2
The obtained kneaded clay is extruded and formed into a honeycomb shape to obtain a honeycomb formed article. The obtained honeycomb formed article is dried and fired, whereby the honeycomb structure can be manufactured
Data Source
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Figure 5~6
AI summary
There is disclosed a honeycomb structure onto which a large amount of catalyst can be carried while suppressing an increase in pressure drop. In a honeycomb structure 100 comprising porous partition walls 1 by which a plurality of cells 2 that become through channels of a fluid are partitioned and in which a plurality of pores 6 are formed. In each of the partition walls 1, pores having pore diameters larger than a thickness of the partition wall 1 in a section thereof which is vertical to an extending direction of the cells 2 are formed so as to occupy 4 to 11% of the total volume of the pores 6 formed in the partition walls 1.