Highly selective SAPO 34 membrane on surface modified clay–alumina tubular support for H2/CO2 separation

The formation and growth of Silicoaluminophosphate (SAPO 34) zeolite membrane was developed on the low cost indigenous clay–alumina tubular substrate modified by cationic polymer as an intermediate layer. The amino (–NH2) and hydroxyl (–OH) groups on the backbone of polymer are responsible for hydrogen bonding between zeolite surface and support surface. Seeding of the support surface accelerates the zeolite crystallization and enhances the formation of homogenous SAPO 34 membrane layer. The seeds were synthesized by hydrothermal process and used to provide nucleation for the membrane growth. The synthesized membranes along with seed crystals were characterized by XRD, FTIR, FESEM, TEM and EDAX analysis. The performance of the membrane formed was evaluated by single gas as well as mixture gas permeation measurement for H2 and CO2. The H2/CO2 separation selectivity of the membrane increased upto 5.88 at room temperature which is more than reported values and the reproducibility towards gas permeation and selectivity of SAPO 34 membrane shows excellent result.

► SAPO 34 zeolite membranes are prepared by ex-situ hydrothermal technique. ► A cationic polymer layer increases the uniform orientation of seed crystals. ► Oriented seed layer reduces the chance of cracking during membrane formation. ► “Reduced defect” membrane will increase the selectivity of H2/CO2 gases. ► Membrane on chitosan modified support shows better results than literature value.