Honeycomb Catalytic Body With Gradient Partition Walls
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Solution Overview
Problem
Conventional honeycomb catalytic bodies face challenges in achieving high purification efficiency while minimizing pressure loss and accommodating limited space, particularly in gasoline engine exhaust gas treatment, due to limitations in cell hydraulic diameter, surface area, and catalyst layer thickness.
Innovation Solution
The honeycomb catalytic body is designed with varying cell hydraulic diameters between inlet and outlet, optimized partition wall permeability, and catalyst distribution, featuring a specific range of cell density and partition wall thickness, along with noble metal catalysts like Pt, Rh, and Pd, to enhance gas permeability and reduce pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cell density is increased to improve purification efficiency, then the transmissibility of components to be removed improves, but the pressure loss increases
Solution Approach 1:
The partition walls are designed with non-uniform thickness, being thinner at the inlet side and thicker at the outlet side. This local variation in thickness allows the inlet region to have lower flow resistance for easier gas entry, while the outlet region provides sufficient structural support and catalytic activity, thereby reducing overall pressure loss while maintaining purification efficiency
Solution Approach 2:
The invention changes the geometric parameter of partition wall thickness from a uniform value to a gradient distribution. By controlling the thickness parameter to decrease from outlet to inlet, the system optimizes the balance between surface area for catalysis and flow resistance, achieving both high purification efficiency and low pressure loss
2Productivity
If the cell hydraulic diameter is decreased to improve transmissibility, then the transmissibility of components to be removed improves, but the pressure loss increases
Solution Approach 1:
The partition walls have different thicknesses at different locations, creating local variations in cell hydraulic diameter. The thinner inlet-side walls create larger effective cell openings for better component transmissibility, while the thicker outlet-side walls maintain structural integrity and catalytic surface area
3Productivity
If the catalyst layer thickness is decreased to improve diffusion speed, then the purification efficiency improves, but the surface area of catalyst layers decreases
Solution Approach 1:
The catalyst layer thickness varies locally across the partition wall, being thinner at the inlet side to facilitate rapid diffusion of components to be removed, and thicker at the outlet side to provide sufficient catalytic reaction surface area. This spatial variation in catalyst thickness optimizes both diffusion speed and total catalytic activity
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 results in improved purification efficiency with reduced pressure loss and allows for compact mounting, effectively treating exhaust gases from gasoline engines even in limited spaces.
Implementation Method 1
the permeability of partition walls constituting a honeycomb structure can be set to a specific numeric range... the partition walls have a permeability of 1.5 × 10 -12 to 5.0 × 10 -12[m2]
Implementation Method 2
a catalytic body having a honeycomb structure (a honeycomb catalytic body) is used... the surfaces of partition walls forming cells carry catalyst layers
Implementation Method 3
the exhaust gas is allowed to flow into the cells of the honeycomb catalytic body from the side of one end face, so that it comes in contact with the catalyst layers on the surfaces of the partition walls
Data Source
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AI summary
There are disclosed a honeycomb structure capable of providing a honeycomb catalytic body which is excellent in purification efficiency with a small pressure loss and which can be mounted even in a limited space, a honeycomb catalytic body which is excellent in purification efficiency with a small pressure loss and which can be mounted even in a limited space, and a manufacturing method of the same. A honeycomb catalytic body 50 of the present invention is a honeycomb catalytic body of a flow-through type through which cells as through channels extend from an inlet to an outlet, both the surfaces of partition walls 4 of a honeycomb structure 1 and the inner surfaces of pores 25 carry a catalyst to form catalyst layers 5, and the catalyst carrying partition walls have a permeability of 1 × 10-12 [m2] or more, preferably 1 × 10-9 [m2] or less.