Study on Organo-Silica-Derived Membranes Using a Robeson-like Plot.

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Industrial carbon dioxide (CO2) utilization requires concentrated CO2 streams at high temperatures.
• Membrane processes are efficient for CO2 separation, but comparability and optimization frameworks are lacking for organo-silica membranes.
• Existing organo-silica membranes for CO2/N2 separation need standardized evaluation methods.

Purpose of the Study:

• To establish a standardized framework for comparing organo-silica membranes for high-temperature CO2 separation.
• To present organo-silica membranes in a Robeson-like plot across various temperatures for comparability.
• To characterize a microporous membrane using a standard precursor and simplified sol-gel method for exemplary comparison.

Main Methods:

• Preparation of a microporous membrane layer using a 1,2-bis(triethoxysilyl)-ethane (BTESE) precursor and a simplified sol-gel method.
• Characterization of temperature-dependent single- and mixed-gas permeances to observe interactions.
• Analysis of the impact of driving forces (vacuum and concentration) on permselectivity and separation factor.
• Evaluation of support structure influence on permeability calculations at elevated temperatures.
• Development of a method for qualitative microstructure assessment via temperature dependencies of diffusion mechanisms (Knudsen, surface, activated).

Main Results:

• A standardized framework and Robeson-like plot for comparing organo-silica membranes across temperatures were presented.
• Temperature-dependent single- and mixed-gas permeances were characterized, revealing interactions.
• The study distinguished between permselectivity and separation factor based on driving forces.
• The influence of the support structure on high-temperature permeability was assessed.
• A method for qualitative microstructure assessment based on diffusion mechanism analysis was demonstrated.

Conclusions:

• The presented framework enables standardized comparability and optimization of organo-silica membranes for CO2 separation.
• Understanding temperature-dependent diffusion mechanisms provides insights into membrane microstructure.
• This work facilitates the development of efficient membranes for industrial CO2 utilization at high temperatures.