Incorporation of aluminosilicate into ZIF-activated carbon membrane for H₂/CO₂ and CH₄/CO₂ separation

For the purification of gases, distillation columns, pressure swing adsorption processes, and membrane technologies have been used. The separation selectivities and permeability’s of gases through membrane technologies are improving day by day. In this study, we developed the zeolitic imidazolate framework (ZIF) membrane with the incorporation of activated carbon (AC) and aluminosilicate (AS). For the preparation of activated carbon, H₃PO₄ is used as an activator agent to create an abundant pore structure. AC acts as an adsorbent and has the ability to store hydrogen gas. As a uniform mixing of AC with ZIF-8 and AS was required therefore powdered activated carbon was used. The Brunauer–Emmett–Teller (BET) surface area of activated carbon derived from red algae was 783.53 m²/g. The X-ray diffraction (XRD) analysis of aluminosilicates reveals that aluminosilicates are crystalline in structure. The surface characteristics of the modified membrane were observed by using the XRD and scanning electron microscopy (SEM) analysis. The produced membrane exhibits both particle homogeneous distribution and efficient adhesion. Single gas (H₂, CH₄, and CO₂) tests are performed at room temperature and at 100 °C. The two mixtures of gases, H₂/CO₂ and CH₄/CO₂, are tested at room temperature and 100 °C. Permeation results from the ZIF membrane reveal the permeation value of H₂ and CO₂ are 1.06 *10^–6, 5.23*10^–8 (mol/m²sPa), respectively, at room temperature. Permeation results from the ZIF-AC-AS membrane reveal the permeation value of CH₄ and CO₂ are 6.95*10^–8, and 7.78*10^–8 (mol/m²sPa), respectively, at room temperature. As the temperature rises from room temperature to 100 °C, the permeation values of CH₄ and CO₂ decrease slightly to 4.92*10^–8 and 6.82*10^–8 (mol/m²sPa), respectively.