Porous Ceramic Honeycomb with Exposed Cerium Dioxide
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Solution Overview
Problem
Porous ceramic structural bodies used as catalyst carriers for purifying exhaust gas face challenges in loading sufficient catalyst without decreasing porosity, which leads to increased pressure loss and reduced catalyst activity, and existing methods like γ-alumina coating can clog pores or weaken the structure.
Innovation Solution
Incorporating cerium dioxide into the ceramic material, with at least a portion exposed on pore surfaces, allows for selective loading of catalyst particles without the need for γ-alumina coating, maintaining structural integrity and porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a coat treatment with γ-alumina is applied to increase specific surface area, then catalyst loading capacity is improved, but porosity decreases and pressure loss increases
Solution Approach 1:
The invention extracts the γ-alumina coating layer from the system and replaces it with cerium dioxide particles incorporated directly into the honeycomb structure. This eliminates the harmful effect of pore clogging while maintaining the beneficial effect of increased catalyst loading capacity through exposed cerium dioxide particles on the pore surfaces.
Solution Approach 2:
The invention changes the material parameter from γ-alumina coating to cerium dioxide incorporation, and controls the particle size of cerium dioxide to be 0.01 μm to 2 μm. This parameter change allows the cerium dioxide particles to provide sufficient surface area for catalyst loading while their small size prevents complete pore blockage, thus maintaining porosity.
2Quantity of substance
If the porosity of the honeycomb structure is decreased to increase catalyst loading, then catalyst activity is improved, but pressure loss increases
Solution Approach 1:
The invention applies local quality by concentrating cerium dioxide particles specifically on the pore surfaces where catalyst loading is needed, rather than uniformly distributing material throughout the structure. This localized approach increases catalyst loading capacity at the critical interfaces while preserving the bulk porosity of the honeycomb structure for efficient gas flow.
3Quantity of substance
If acid treatment and heat treatment are performed to increase specific surface area, then catalyst loading is improved, but structural strength may decrease
Solution Approach 1:
The invention applies preliminary action by incorporating cerium dioxide particles into the honeycomb structure during the manufacturing process, before the final sintering step. This allows the cerium dioxide to become an integral part of the structure, providing catalyst loading capacity without requiring subsequent acid or heat treatments that could compromise structural strength.
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 approach enhances catalyst loading and activity while preventing pressure loss, as demonstrated by improved NO2 conversion rates and structural strength, without the need for additional coating processes.
Implementation Method 1
at least a part of the catalyst particulates is loaded by the particles of the cerium dioxide exposed on the pore surfaces
Data Source
AI summary
A honeycomb structure is formed of a porous ceramic material and has pores in the structural body, wherein cerium dioxide is present in a state that it is incorporated in the structural body in the ceramic material, and at least a part of cerium dioxide particles is exposed on pore surfaces of the pores. The ceramic material includes cordierite or silicon carbide as a major component, the ratio of the cerium dioxide to the ceramic material is in the range of from 1.0% by mass to 10.0% by mass, and at least a part of catalyst particulates of a platinum group element such as platinum or palladium is loaded by the cerium dioxide particles.