OSDA-Free CHA Zeolite Membrane Fabrication
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Solution Overview
Problem
The synthesis of high-performance zeolite membranes without organic structure directing agents (OSDAs) is challenging due to the high cost and energy consumption associated with conventional methods, particularly the calcination process, and the difficulty in forming small pore channels and large cavities in CHA type zeolites without OSDAs, which limits their practical application in CO2 separation.
Innovation Solution
A method for fabricating a continuous CHA type zeolite membrane using an alkali metal hydroxide without OSDAs through hydrothermal synthesis, optimizing the Si/Al ratio and hydrothermal conditions to achieve cost-effective and energy-efficient production, enabling CO2/N2 and CO2/CH4 separation comparable to conventional membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional zeolite membrane synthesis using organic structure directing agents (OSDAs) is performed, then high-performance membranes with proper pore structure are obtained, but the synthesis cost increases and energy consumption increases due to calcination process
Solution Approach 1:
The patent removes the OSDA component from the synthesis system entirely, using only inorganic reagents (alkali metal hydroxide, silica, aluminum salt) to form CHA-type zeolite membranes. This extraction of the organic additive eliminates the need for subsequent calcination to remove OSDAs, directly resolving the energy consumption contradiction while maintaining membrane performance through optimized hydrothermal synthesis conditions.
Solution Approach 2:
The patent modifies the synthesis parameters by using alkali metal hydroxide instead of OSDAs as the structure-directing component, and by optimizing the hydrothermal treatment conditions (temperature, time, pH, precursor ratios). These parameter changes enable the formation of well-crystallized CHA-type zeolite membranes with proper pore structures without requiring high-temperature calcination, thus reducing energy consumption while maintaining separation performance.
2Reliability
If conventional zeolite membrane synthesis using organic structure directing agents (OSDAs) is performed, then high-performance membranes with proper pore structure are obtained, but the synthesis cost increases
Solution Approach 1:
The patent extracts and eliminates the expensive OSDA component from the synthesis system, replacing it with inexpensive inorganic reagents. This removal of the organic structure-directing agent directly reduces material costs while the optimized hydrothermal synthesis protocol maintains the ability to form functional CHA-type zeolite membranes with proper molecular sieving capabilities.
Solution Approach 2:
The patent employs inexpensive, readily available inorganic reagents (alkali metal hydroxide, silica, aluminum salt) instead of costly organic OSDAs. These simple, cheap reagents can be easily disposed of or recycled without the complex handling and removal requirements of organic compounds, further reducing both material and processing costs while achieving the desired membrane performance.
3Use of energy by stationary object
If zeolite membrane synthesis without organic structure directing agents is attempted, then cost and energy consumption are reduced, but the formation of small pore channels and large cavities in CHA type zeolites becomes difficult
Solution Approach 1:
The patent achieves precise pore structure formation without OSDAs by carefully controlling hydrothermal synthesis parameters including pH (adjusted using alkali metal hydroxide), temperature, reaction time, and the ratios of silica to aluminum precursors. These parameter optimizations enable the spontaneous organization of CHA-type crystalline structures with well-defined small pore channels and cavities, maintaining manufacturing precision while avoiding OSDA-related costs and energy consumption.
Solution Approach 2:
The patent uses alkali metal hydroxide as an intermediary substance that facilitates the formation of CHA-type zeolite pore structures without requiring organic OSDAs. The hydroxide ions act as a mediator during hydrothermal synthesis, promoting the self-assembly of silicon and aluminum species into the characteristic CHA framework with its specific pore topology, thereby achieving precise pore structure formation through inorganic rather than organic mediation.
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 OSDA-free CHA type zeolite membrane exhibits high CO2/N2 and CO2/CH4 separation factors with moderate CO2 permeance, maintaining performance under wet conditions and demonstrating long-term stability, making it suitable for post-combustion carbon capture and bio-gas/natural gas upgrading.
Implementation Method 1
fabricating a CHA type zeolite membrane by hydrothermally synthesizing the support on which the seed layer is formed in a synthetic precursor solution containing an alkali metal hydroxide and silica
Implementation Method 2
high performance for separating molecular mixtures based on their intrinsic molecular sieving ability and/or their capability for preferential adsorption
Implementation Method 3
high performance for separating molecular mixtures based on their intrinsic molecular sieving ability and/or their capability for preferential adsorption
Data Source
AI summary
The present invention relates to a method of fabricating an organic structure directing agent-free CHA type zeolite membrane and a membrane fabricated thereby, and more particularly to a method of fabricating a continuous CHA type zeolite membrane, which exhibits CO2/N2 and CO2/CH4 separation performances comparable with those of conventional membranes, in a cost-effective manner without a calcination process by hydrothermal synthesis using an alkali metal hydroxide without using an organic structure directing agent, and to a membrane fabricated thereby.