Membrane Filter Production via Low-Temperature Calcination
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Solution Overview
Problem
Existing exhaust gas treatment devices for internal combustion engines face efficiency degradation and loss of membrane effectiveness due to high-temperature calcination processes, particularly for membranes made of cordierite or SiC, which affects catalytic phase efficiency and soot filtration performance.
Innovation Solution
A method for producing membrane particle filters that synthesizes membranes using a honeycomb monolith with a network of channels, applying a wash-coat process with an aqueous suspension containing glass powder and a plasticizer, and calcining at a temperature below 800°C, allowing for 'wall through' filtration and maintaining stability at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high-temperature calcination (1300-1500°C) is used to ensure membrane adhesion and stability, then membrane structural stability is improved, but catalytic phase efficiency degrades
Solution Approach 1:
The invention changes the calcination temperature parameter from conventional high temperatures (1300-1500°C) to a lower range (900-1100°C), which preserves catalytic phase efficiency while still achieving adequate membrane adhesion and structural stability through the specific wash-coat formulation
Solution Approach 2:
The invention uses a composite wash-coat formulation containing glass powder (3-5% mass concentration) combined with frittable powder (20-30% mass concentration) that creates a bonding matrix capable of ensuring membrane adhesion at lower calcination temperatures, thereby protecting the catalytic phase from degradation
2Strength
If high-temperature calcination (1300-1500°C) is used to ensure membrane adhesion, then membrane adhesion is improved, but membrane efficiency for low-temperature applications is lost
Solution Approach 1:
The invention optimizes the calcination temperature parameter to a specific range (900-1100°C) that balances membrane adhesion strength with the preservation of low-temperature filtration efficiency, avoiding the temperature threshold that causes efficiency loss
Solution Approach 2:
The invention uses glass powder as a bonding matrix that replicates the adhesion function of high-temperature processes but at lower temperatures, creating a copy of the bonding effect that preserves membrane efficiency
3Stability of the object's composition
If multiple coating operations are performed to build membrane thickness, then membrane adhesion and stability are improved, but processing time and complexity increase
Solution Approach 1:
The invention applies multiple coating operations (at least two) with decreasing mass concentrations of frittable powder (20-30% in first operation, reduced in subsequent operations) to build up membrane stability efficiently, where the reduced concentration in later operations maintains stability while reducing total processing time
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 solution enhances the stability and efficiency of the membrane filters, maintaining high filtration efficiency and catalytic performance even at elevated temperatures, thereby improving the treatment of exhaust gases from internal combustion engines.
Implementation Method 1
the deposition on these walls of a membrane adhering to the wall, obtained by an operation called 'wash coat'... during which part of the walls of the monolith are placed in contact with an aqueous suspension of a frittable powder
Implementation Method 2
finally calcining the coated monolith at a temperature below 800°C... such that the aqueous suspension also comprises glass powder and a plasticizer
Implementation Method 3
the mass concentration of frittable powder and glass powder in the aqueous suspension being reduced at each new operation... the membrane being obtained by repeating the coating operation
Implementation Method 4
the aqueous suspension also comprises glass powder and a plasticizer... the concentration of plasticizer of the order of 1% by mass
Implementation Method 5
the membrane being permeable, and therefore allows a so-called 'wall through' filtration, meaning that the exhaust gases from the internal combustion engine that will pass through the filter of the invention will pass through the walls of the filter, and, in fact, my membrane as well
Data Source
AI summary
The invention relates to a process for producing a membrane filter comprising the steps of selecting a honeycomb monolith with a network of channels separated by porous channel walls and the deposition on these walls of a membrane that adheres to the wall, obtained by a coating operation during which some of the walls of the monolith are placed in contact with an aqueous suspension of a sinterable powder of a constituent material of the monolith then by drying and finally by calcining the coated monolith. The membrane is obtained by repeating the coating operation, the weight concentration of sinterable powder in the aqueous suspension being reduced at each new operation, and the calcination is carried out at a temperature below 1000°C.