Zone Coated Monolith Capillary Self-Service
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Solution Overview
Problem
The existing methods for zone coating catalysed monolithic substrates, particularly wall flow filters, are expensive and difficult to control due to the need for precise dosing and application of washcoat slurry, often requiring vacuum assistance which complicates even distribution and leads to excess slurry issues.
Innovation Solution
A method utilizing sol-solutions containing catalyst carrier precursors and metal catalyst precursors that are sucked into the pores of the monolithic substrate solely by capillary forces, eliminating the need for external vacuum or pressure, and allowing for easier and more controlled zone coating by dipping the substrate into the sol-solutions and allowing capillary action to distribute the coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If washcoat slurry is applied by pouring or dipping with vacuum assistance, then the substrate can be coated, but the process becomes difficult to control and leads to excess slurry application
Solution Approach 1:
The monolithic substrate performs self-coating by utilizing its own capillary forces to draw the sol solution into its pores during the dipping process, eliminating the need for external vacuum assistance and achieving automatic, controlled distribution of the coating material throughout the substrate structure
Solution Approach 2:
The mechanical vacuum assistance system is replaced by capillary forces inherent to the porous substrate structure, substituting an external mechanical control system with a passive physical phenomenon that naturally regulates the coating process
2Manufacturing precision
If vacuum is applied to raise slurry to desired coating level, then coating can be achieved, but excess slurry must be blown out by air knife which complicates the process
Solution Approach 1:
The substrate automatically regulates the coating level through its capillary properties, drawing the sol solution to the appropriate depth without external vacuum control, and the porous structure naturally limits penetration depth, eliminating the need for air knives or other excess material removal devices
Solution Approach 2:
The coating process utilizes changes in capillary pressure and surface tension parameters of the sol solution to achieve controlled penetration depth and uniform distribution, replacing mechanical level control with physicochemical parameter regulation
3Adaptability or versatility
If zone coating is performed on wall flow filters with closed channels, then selective catalysis can be achieved, but air knife application is hindered by filter walls
Solution Approach 1:
The mechanical air knife system is replaced by capillary action that naturally flows through the complex internal channel structure of wall flow filters, allowing uniform coating distribution in zones with closed channels where traditional mechanical methods fail
4Manufacturing precision
If precise dosing of washcoat slurry is required for zone coating, then catalyst distribution can be controlled, but the process becomes expensive and difficult
Solution Approach 1:
The substrate itself performs the dosing function by utilizing its porous structure and capillary properties to automatically draw in and distribute the sol solution uniformly throughout the designated zones, eliminating the need for complex external dosing equipment and procedures
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 method simplifies the zone coating process, reduces waste, and ensures even distribution of catalysts within the monolithic substrate, making it more efficient and cost-effective for preparing catalysed monoliths with multiple catalyst zones.
Implementation Method 1
suck up the sol-solution solely by capillary forces into pores of the walls of zone to be coated
Data Source
AI summary
Method for zone coating of monolithic substrates by using different sol-solution containing different catalyst carrier precursors and metal catalyst precursors and suction of one of the sol-solution up into pores in the walls of the zone to be coated, solely by capillary forces and another different sol-solution into the walls of another zone to be coated by capillary forces.