Synthesis and Characterization of Thin-layer SAPO-34 Membrane on Disk-Shaped Mullite Support for Natural Gas Sweetaning

High reproducibility SAPO- membranes were fabricated on microporous mullite supports via the secondary growth method for the first time. The ceramic supports were prepared via calcination of kaolin powder, followed by a leaching post-treatment. Influence of synthesis temperature on formation of nanoporouse SAPO investigated at three levels: 185,195 and 220 °C. Morphology and crystalline structure of the synthesized membranes were characterized by SEM and XRD, respectively. It was found out that chemical nature of the support and synthesis temperature have significant effects on the nucleation process. The more regular in shape and the less intergrown crystals on the membrane surface layers were observed at higher synthesis temperature. Gas permeation experiments were conducted to characterize the membranes separation ability. Effects of synthesis temperature were also investigated on single permeances of CO2and CH4 and CO2/CH4 ideal selectivity.It was observed that increasing synthesis temperature increases the zeolite layer thickness and eventually decreases the single gas permeances, however, CO2/CH4 ideal selectivity increases as a result of better membrane surface coverage with SAPO-34crystals as confirmed with the SEM results.According to the results of conducted experimental design and at1bar feed pressure, the ranges of gas permeances and CO3/CH ideal selectivities were10 -9to10 -6mol/m2 s Pa) and 5.78-17.39, respectively. Mullite as a novel, cheap and easily processable support was found as a good candidate for synthesis of SAPO-34membranes in separation of CO2 from CH 4.

Keywords:

SAPO-34 membranes , Mullite support , Synthesis temperature , Gas separation , CO2permeance