Synthesis of ZIF-8 tubular membrane via solvent evaporation seeding coupled with microwave assisted heating method for separation of small molecule gases.

In this work, we systematically study the performance of tubular ZIF-8 membranes in the separation of small molecules including H2, CO2, N2 and CH4. The tubular ZIF-8 membranes were synthesized on α-alumina support via novel dual approach known as solvent evaporation seeding coupled with microwave assisted growth. The durations for the growth of the seed layer through solvent evaporation and membrane layer via microwave heating were varied. The crystallinity and morphology of the resultant membranes were evaluated by using XRD, SEM and IFM analyses. The performance of the resultant tubular ZIF-8 membranes was assessed for small molecule gases permeation at various pressures and temperatures. Highest flux ranging from 0.02 to 0.61 mol/m2s were obtained for gases CO2, CH4, N2, and H2 at feed pressure of 10 bar, whereas highest ideal selectivity of 12.4, 9.3 and 6.9 were obtained for H2/CH4, CO2/CH4, N2/CH4, respectively, at feed pressure of 10 bar and temperature of 30 °C. This work reveals that the tubular ZIF-8 membrane can be synthesized via a feasible and reproducible solvent evaporation seeding coupled with microwave assisted growth method, which can be further explored for the upscaling of the ZIF-8 tubular membrane in pilot scale for gas separation application.

Biomethane generation from biogas upgrading by means of thin-film composite membrane comprising Linde T and fluorinated polyimide: optimization of fabrication parameters.

Generation of biogas from organic substances is an attractive evolution of energy generation from fossil-based energy supply to renewable resources. In order to exhibit viability in terms of technical execution while being economically feasible, successful purification strategies for biomethane formation must be applicable to industrial gas streams at realistic pressures and temperatures. Membrane-based upgrading technologies have great potential to promote biogas processes because they involve less energy and low maintenance. However, the development of membranes with good polymer-filler contact and minimum defects remains a great challenge. Hitherto, researchers have been making many attempts at developing an established route to fabricate thin-film composite membranes. In the present work, an innovative coupling between Linde T and fluorinated polyimide was employed for biogas upgrading. A facile technique for membrane fabrication was proposed via optimization of the fabrication parameters. The results indicated that composite membrane fabricated with 2 hours of total dispersion duration demonstrated a homogeneous distribution of Linde T particles in the fluorinated polyimide matrix and improved the separation characteristics by up to 172% in upgrading biomethane quality. Thus, the fabricated membrane is feasible to be employed for large-scale and lucrative production with enhanced performance in biogas purification via the feasible fabrication method employed in this work.