Synthesis of inorganic and polymeric membranes with sapo-44 zeolite for gas separation
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Date
2015-09-01
Authors
Siti Nadiah Mustafa Kamal
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Abstract
In the present research, inorganic and polymeric membranes involving SAPO-44 application were studied. Inorganic membranes were synthesized on α-alumina disc support by secondary growth method and the effect of calcination temperature of inorganic membrane was investigated. Meanwhile in polymeric membrane study, polyethersulfone (PES) membranes filled with SAPO-44 zeolite particles were fabricated via phase inversion method. The effects of PES membrane synthesis parameters, which are types of co-solvents, PES concentration (17-27 wt%), evaporation time (30 - 2700 s) and polydimethylsiloxane (PDMS) concentration (1 - 5 wt%) were investigated in order to study the changes in membrane morphology and gas performance before adding SAPO-44 particles. Then, the effects of SAPO-44 loading (3 - 10 wt%) were studied. The inorganic membranes were tested for single gas permeation of CO2 and N2, while for polymeric membrane, additional CH4 and H2 permeation tests were also conducted. Calcination temperature conducted at 375°C formed defect-free SAPO-44 membrane with CO2 displayed more permeable through the SAPO-44 zeolite membrane compare to N2 (CO2/N2 selectivity of 1.07). At the higher temperature, the crystallinity of SAPO-44 zeolite was lost due to the disorganization of zeolite. In contrast, the addition of co-solvent into the PES polymer solution decreased the dope viscosity and delayed liquid-liquid demixing during phase inversion. The microvoids were formed on top of substructure layer and the microvoids layer became thicker due to the increasing of solvent evaporation time. The PDMS coating on the PES membrane formed a dense skin layer and exhibited higher selectivity compared to the uncoated membrane. 20PT-3 is the optimum membrane among other fabricated polymeric membranes in this work with CO2 permeance of 44.86 GPU. The CO2 permeance was increased about four times when adding 10 wt% of SAPO-44 in PES/PDMS membrane.