Honeycomb Filter Zeolite Loading and Cell Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional honeycomb structures for exhaust gas purification require separate components for particulate matter (PM) capture and NOx conversion, occupying significant space in exhaust gas lines, and existing NOx conversion rates in urea SCR devices using these structures are insufficient.
Innovation Solution
A honeycomb filter with a honeycomb structure that supports a large amount of zeolite, having a porosity of 55-65%, cell density of 46.5-62 pcs/cm², and a thickness of 0.2-0.3 mm, incorporating both large and small volume cells with a specific area ratio, enhancing NOx conversion efficiency while maintaining PM capture capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate honeycomb structures are used for PM capture and NOx conversion, then each function can be optimized independently, but the overall apparatus occupies significant space in exhaust gas lines
Solution Approach 1:
The patent combines PM capture and NOx conversion functions into a single honeycomb filter structure. The honeycomb walls are impregnated with both a PM capture layer (containing basic substances like barium carbonate) and an NOx conversion catalyst (containing zeolite and precious metals), allowing both purification functions to occur simultaneously within one component, thereby reducing the overall apparatus volume.
2Reliability
If a large amount of zeolite is supported on cell walls to improve NOx conversion, then NOx conversion rate increases, but pressure loss increases and catalyst may deactivate
Solution Approach 1:
The patent applies different functional layers with specific properties to different aspects of the honeycomb walls. The PM capture layer contains basic substances for particulate trapping, while the NOx conversion layer contains zeolite and precious metals. This localized functional differentiation allows high NOx conversion efficiency without requiring excessive zeolite throughout the entire structure, thereby controlling pressure loss.
Solution Approach 2:
The honeycomb filter uses composite material composition on the cell walls, combining PM capture materials (basic substances like barium carbonate) with NOx conversion catalysts (zeolite and precious metals). This composite structure enables both functions to work synergistically, achieving high NOx conversion rates while maintaining acceptable pressure loss characteristics through optimized material distribution and interaction.
3Reliability
If cell wall porosity is increased to support more zeolite, then NOx conversion improves, but structural strength decreases
Solution Approach 1:
The patent utilizes porous honeycomb wall structures with controlled porosity (30-70%) to support the impregnation of PM capture and NOx conversion catalysts. The porous structure provides sufficient surface area for catalyst support while maintaining structural integrity through the honeycomb geometry and controlled pore size distribution, balancing NOx conversion efficiency with mechanical 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
The honeycomb filter achieves a high NOx conversion rate when used in urea SCR devices without significantly increasing pressure loss or deactivating the catalyst, while effectively capturing PM, thus reducing the overall volume of the exhaust gas purification apparatus.
Implementation Method 1
The zeolite is supported on the cell walls of the honeycomb structure
Implementation Method 2
a catalyst for converting NOx is supported on cell walls
Implementation Method 3
PM contained in exhaust gases are captured by the cell walls upon passing through the honeycomb structure. The cell walls of the honeycomb structure function as filters through which the exhaust gases are purified.
Data Source
AI summary
A honeycomb filter includes a honeycomb structure and a zeolite. The honeycomb structure has cell walls to define cells between the cell walls. The zeolite is supported on the cell walls. An amount of the zeolite is from about 80 g/L to about 150 g/L. A porosity of the cell walls is from about 55% to about 65%. A cell density in a cross section perpendicular to the longitudinal direction is from about 46.5 pcs/cm2 to about 62.0 pcs/cm2. A thickness of the cell walls is from about 0.2 mm to about 0.3 mm. The cells include a large volume cell and a small volume cell. An area ratio of a cross sectional area of the large volume cell relative to a cross sectional area of the small volume cell is from about 1.4 to about 2.4.