Dehydration-Rehydration Synthesis for Microporous Crystal Membranes
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Solution Overview
Problem
Current hydrothermal processes for synthesizing microporous crystals, such as zeolites, are slow and costly, limiting the feasibility of rapid and cost-effective production of microporous crystal membranes for applications like CO2 capture.
Innovation Solution
A dehydration-rehydration synthesis protocol is employed, where a gel is first dehydrated to induce crystal nucleation and then rehydrated with a controlled water addition rate to accelerate the crystallization of microporous crystals, allowing for the rapid synthesis of microporous crystal membranes compatible with polymer roll-to-roll technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional hydrothermal processes are used for synthesizing microporous crystals, then the crystallization can proceed with standard conditions, but the crystallization time is long and production cost is high
Solution Approach 1:
The patent applies preliminary action by removing water from the gel before crystallization to pre-concentrate the reactants and create a more favorable environment for rapid crystal growth. This pre-treatment step prepares the system in advance to accelerate the subsequent crystallization process, reducing overall synthesis time from days to hours.
Solution Approach 2:
The patent changes key parameters of the synthesis process by controlling water removal and addition rates, temperature profiles, and pH conditions. By dynamically adjusting these parameters—particularly the water activity during gel drying and the controlled rehydration rate—the crystallization kinetics are enhanced, achieving faster crystal growth while maintaining quality.
2Productivity
If water is removed rapidly from the gel, then crystallization may be accelerated, but uncontrolled water removal can lead to poor crystal quality and morphology
Solution Approach 1:
The patent employs feedback control by monitoring the water removal rate and adjusting the drying conditions accordingly. The controlled water removal process maintains optimal moisture content to prevent premature cracking or deformation of the gel structure, ensuring that crystals develop with good quality and uniform morphology while still achieving accelerated crystallization.
Solution Approach 2:
The patent applies dynamics by using a controlled, dynamic water removal and addition process rather than static conditions. The water is removed at a controlled rate and then added back at a specific rate (0.5-2.0 fold the removal rate) to dynamically adjust the gel's water activity, creating optimal conditions for both rapid crystallization and high crystal quality throughout the process.
3Productivity
If the water addition rate during rehydration is too high, then the crystallization process speeds up, but the crystal morphology and quality deteriorate
Solution Approach 1:
The patent optimizes the water addition rate parameter during rehydration to achieve the best balance between crystallization speed and crystal quality. By controlling the water addition rate to be 0.5-2.0 fold the removal rate, the process maintains optimal supersaturation levels that promote rapid yet controlled crystal growth, preserving good morphology while achieving fast production.
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 significantly reduces the crystallization time of microporous crystals, enabling the production of high-quality microporous crystal membranes within the hour time scale, aligning with polymer roll-to-roll fabrication constraints and offering a cost-effective solution for industrial applications.
Implementation Method 1
heating the gel for a first time period, whereupon a first volume of water is removed from the gel
Implementation Method 2
heating the gel for a second time period, during which a second volume of water is added to the gel
Implementation Method 3
heating the gel for a first time period, whereupon a first volume of water is removed from the gel and microporous crystal nuclei form
Data Source
AI summary
A method of making a microporous crystal material, comprising: a. forming a mixture comprising NaOH, water, and one or more of an aluminum source, a silicon source, and a phosphate source, whereupon the mixture forms a gel; b. heating the gel for a first time period, whereupon a first volume of water is removed from the gel and micoroporous crystal nuclei form, the nuclei having a framework; and c.(if a membrane is to be formed) applying the gel to a solid support seeded with microporous crystals having a framework that is the same as the framework of the nuclei; d. heating the gel for a second time period. during which a second volume of water is added to the gel; wherein the rate of addition of the second volume of water is between about 0.5 and about 2.0 fold the rate of removal of the first volume of water.