Honeycomb Partition Wall Porosity for Fast Catalyst Heating
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Solution Overview
Problem
Existing pillar-shaped honeycomb structures face challenges in achieving both weight reduction and high strength while ensuring rapid catalyst temperature activation and preventing cracks during heating and cooling cycles.
Innovation Solution
A pillar-shaped honeycomb structure with controlled porosity variation, where the average pore diameter is 10 μm or less, average porosity is 40 to 70%, and the difference between maximum and minimum porosity is 11% or less, along with a thickness of 50 to 150 μm, made of ceramics with 90% cordierite, to enhance strength and reduce weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the partition walls are thinned or porosity is increased to reduce weight and raise catalyst temperature quickly, then the heat capacity of the partition walls is reduced and catalyst activation time is shortened, but the strength of the pillar-shaped honeycomb structure decreases
Solution Approach 1:
The patent applies local quality by creating different porosity levels in different regions of the partition walls. The surface region (0-15% thickness) has lower porosity (30-60%) to maintain strength, while the internal region (15-50% thickness) has higher porosity (60-80%) to reduce overall weight and heat capacity. This spatial variation in porosity allows simultaneous optimization of strength and heating performance.
Solution Approach 2:
The patent changes the porosity parameter through the thickness of the partition walls, creating a gradient from 30-60% at the surface to 60-80% in the internal region. This parameter variation enables the partition walls to have lower overall heat capacity for faster heating while maintaining sufficient surface strength to prevent cracks during thermal cycles.
2Loss of time
If the partition walls are thinned to reduce weight and heat capacity, then the catalyst layer temperature can be raised quickly, but the partition walls become more susceptible to cracks during repeated heating and cooling cycles
Solution Approach 1:
The patent applies local quality by concentrating lower porosity (30-60%) in the surface region where mechanical strength and crack resistance are most critical, while allowing higher porosity (60-80%) in the internal region where weight reduction is prioritized. This spatial differentiation ensures the surface can withstand thermal stress while the overall structure remains lightweight.
3Weight of stationary object
If the porosity of the partition walls is increased to reduce weight, then the heat capacity is reduced and catalyst activation is accelerated, but the structural integrity and strength are compromised
Solution Approach 1:
The patent applies local quality by creating a porosity gradient where the surface region (0-15% thickness) maintains lower porosity (30-60%) to preserve structural integrity, while the internal region (15-50% thickness) achieves higher porosity (60-80%) for weight reduction. This localized differentiation allows the partition walls to be lighter overall while maintaining sufficient strength at critical surfaces.
Solution Approach 2:
The patent creates a composite structure within the partition walls by combining regions of different porosity, effectively creating a composite material system where low-porosity surface material provides strength and high-porosity internal material reduces weight. This internal composite structure optimizes both mechanical properties and thermal performance.
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 structure enables rapid catalyst temperature activation while maintaining structural integrity, ensuring high strength and effective pollutant purification performance.
Implementation Method 1
it is necessary to reduce the heat capacity of the partition walls by thinning the partition walls or increasing the porosity. By doing so, the temperature of the partition walls can be raised in a short time after the exhaust gas starts to flow, and the temperature of the catalyst layer formed on the surface of the partition walls can be raised to the activation temperature in a short time.
Implementation Method 2
A catalyst layer containing a catalyst described above can be formed on the surface of the partition walls
Implementation Method 3
oxidation catalyst, reduction catalyst, three-way catalyst
Data Source
AI summary
A pillar-shaped honeycomb structure including an outer peripheral side wall, and a plurality of partition walls disposed on an inner peripheral side of the outer peripheral side wall, the plurality of partition walls partitioning a plurality of cells forming flow paths from a first end surface to a second end surface, whereinan average pore diameter of the partition walls measured by a mercury porosimeter is 10 μm or less, andwhen a cross section of the plurality of partition walls is observed with an X-ray microscope and porosities (%) of each partition wall is measured in a thickness direction from one surface to the other surface of each partition wall, an average porosity of each partition wall is 40 to 70%, and a difference between a maximum value and a minimum value of the porosity of each partition wall is 11% or less.