Honeycomb Catalyst Pore Structure for Purification and Thermal Shock
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Solution Overview
Problem
High porosity in honeycomb catalyst structures reduces the contact area between exhaust gases and catalysts, leading to decreased purification efficiency and increased thermal expansion, compromising thermal shock resistance.
Innovation Solution
A honeycomb catalyst with porous partition walls having a porosity of 45-70% and a total area of macro pores with the largest diameter of 50% or more, allowing for increased catalyst loading and effective gas diffusion while minimizing pores closed with catalyst, thereby enhancing purification efficiency and thermal shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the porosity of partition walls is increased to enhance catalyst loading, then the amount of catalyst that can be loaded increases, but pores become closed with catalyst which reduces the contact area between exhaust gas and catalyst, leading to decreased purification efficiency
Solution Approach 1:
The patent utilizes a honeycomb structure with porous partition walls having controlled porosity (30-70%) and specific pore size distribution. The porous structure provides high surface area for catalyst loading while maintaining open pores for gas flow. The key is controlling the pore size distribution to ensure pores remain accessible to exhaust gas while providing sufficient surface area for catalyst deposition.
Solution Approach 2:
The patent optimizes specific parameters including porosity (30-70%), average pore diameter (10-30 μm), and pore size distribution to balance catalyst loading capacity with gas-catalyst contact efficiency. By carefully controlling these parameters, the structure achieves high catalyst loading while maintaining adequate pore openness for effective purification.
2Quantity of substance
If the porosity of partition walls is increased to enhance catalyst loading, then the amount of catalyst that can be loaded increases, but the thermal expansion increases, compromising thermal shock resistance
Solution Approach 1:
The patent optimizes porosity within a specific range (30-70%) to balance catalyst loading capacity with thermal shock resistance. This controlled parameter range ensures sufficient catalyst loading while maintaining adequate structural integrity and minimizing thermal expansion. The specific pore size distribution also contributes to reducing thermal stress concentration.
Solution Approach 2:
The honeycomb structure serves as a composite support material combining ceramic or metallic base material with controlled porous structure. This composite approach allows tuning of thermal properties while maintaining mechanical strength and catalyst loading capacity, improving resistance to thermal shock.
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 solution achieves a good purification efficiency by maximizing the contact area between exhaust gases and catalysts while controlling thermal expansion, resulting in a honeycomb catalyst with improved performance in both purification efficiency and thermal shock resistance.
Implementation Method 1
a total area of macro pores having the largest pore diameter of larger than 10 μm is 50% or more with respect to a total area of the pores
Data Source
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Figure 3~4
AI summary
There is disclosed a honeycomb structure usable as a support of a honeycomb catalyst onto which a large amount of catalyst can be loaded and which has a good purification efficiency, and the honeycomb structure includes porous partition walls 5 defining a plurality of cells to form through channels of a fluid and having a plurality of pores 10 therein, wherein a porosity of the partition walls 5 is from 45 to 70%, and in a cross section perpendicular to an extending direction of the cells, a total area of macro pores 12 having the largest pore diameter of larger than 10 µm is 50% or more with respect to a total area of the pores 10.