Gradient Si/Al Zeolite Membrane for Dehydration
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Solution Overview
Problem
Zeolite membranes with high Si/Al ratios exhibit high hydrothermal resistance but low water flux, while those with low Si/Al ratios have high water flux but are prone to membrane peeling and require lengthy production times due to the use of different starting material solutions for each layer.
Innovation Solution
A zeolite membrane complex with a porous support, where the Si/Al ratio increases from the interface with the support towards the membrane inner portion and decreases towards the surface, allowing for a continuous gradient in the Si/Al ratio, is produced using a starting material solution with two Al sources of different solubilities, enabling efficient hydrothermal synthesis and reducing membrane peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a zeolite membrane with high Si/Al ratio is used, then hydrothermal resistance is improved, but water flux deteriorates
Solution Approach 1:
The patent applies local quality by creating a zeolite membrane with a continuous Si/Al ratio gradient, where different regions of the membrane have different Si/Al ratios optimized for their specific functions: the support-proximal region has higher Si/Al ratio for hydrothermal resistance, while the surface region has lower Si/Al ratio for high water flux. This spatial variation in composition resolves the contradiction between hydrothermal resistance and water flux.
Solution Approach 2:
The patent creates a composite zeolite membrane structure that combines regions with different Si/Al ratios within a single continuous membrane. This composite approach integrates the advantages of both high-Si/Al-ratio materials (hydrothermal resistance) and low-Si/Al-ratio materials (water flux) into one functional membrane, eliminating the need for separate layers and their associated adhesion problems.
2Productivity
If a zeolite membrane with low Si/Al ratio is used, then water flux is improved, but membrane peeling occurs
Solution Approach 1:
The patent applies local quality by creating a zeolite membrane with a continuous Si/Al ratio gradient, where different regions of the membrane have different Si/Al ratios optimized for their specific functions: the support-proximal region has higher Si/Al ratio for hydrothermal resistance, while the surface region has lower Si/Al ratio for high water flux. This spatial variation in composition resolves the contradiction between hydrothermal resistance and water flux.
Solution Approach 2:
The patent creates a composite zeolite membrane structure that combines regions with different Si/Al ratios within a single continuous membrane. This composite approach integrates the advantages of both high-Si/Al-ratio materials (hydrothermal resistance) and low-Si/Al-ratio materials (water flux) into one functional membrane, eliminating the need for separate layers and their associated adhesion problems.
3Manufacturing precision
If separate starting material solutions are used for forming different zeolite membrane layers, then composition control is improved, but production time increases
Solution Approach 1:
The patent merges the formation of multiple zeolite membrane layers with different Si/Al ratios into a single hydrothermal treatment step. By incorporating multiple Al sources with different solubilities into one starting material solution, the membrane is formed as a continuous structure with a Si/Al ratio gradient in a single process, eliminating the need for sequential layer formation and reducing production time significantly.
Solution Approach 2:
The patent utilizes parameter changes in the starting material solution, specifically employing multiple Al sources with different solubilities, to achieve continuous Si/Al ratio variation within the membrane during a single hydrothermal treatment. This approach maintains precise composition control while simplifying the production process.
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 zeolite membrane complex achieves high water flux and hydrothermal resistance while suppressing membrane peeling, allowing for efficient and stable separation of mixed substances, particularly suitable for dehydration applications.
Implementation Method 1
a zeolite membrane having a high Si/Al ratio has high hydrothermal resistance and a zeolite membrane having a low Si/Al ratio has high water flux
Implementation Method 2
Since the pure silica membrane has high hydrophobicity in Document 2, it is thought that the water flux is low
Data Source
AI summary
A zeolite membrane complex includes a porous support and a zeolite membrane formed on the support. In the zeolite membrane, a Si/Al ratio which is a molar ratio becomes larger as it goes from an interface portion with the support toward a membrane inner portion and the Si/Al ratio becomes smaller as it goes from the membrane inner portion toward a surface portion opposite to the support.