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In the synthesis process of zeolite membranes, the zeolites crystals are crystallized and grow during crystallization period to form polycrystalline film.Secondary growth method is an effective method to synthesis high quality zeolite membranes which involves two main steps which are coating and hydrothermal treatment (HT) synthesis. There are several problems associated with the coating process in secondary growth method such as lack of good adherence of the seeds, rough surface of the support, and thermal mismatch between the zeolite seeds and supports during hydrothermal process. In order to solve these issues, an intermediate layer (buffer layer) could be applied between the support and the seeds layer hence to reduce the defects forms during the hydrothermal treatment (HT) synthesis process. In current study, two different types of intermediate layer were studied and results were compared in terms of zeolite seeds coverage on the surface of the support and zeolite layer formed during subsequent hydrothermal treatment (HT) to form zeolite membranes. The formed zeolite membranes were characterized with X-Ray diffraction (XRD) and scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDX).

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Zeolite membranes possess well defined pore structures which able to separate gasses with high selectivity. The separation between adsorptive and non-adsortive gasses depends on the affinity of permeating gas molecules with the zeolites structures whereby different types of cations resides in the zeolitic framework will affect the permeselectivity of the membranes. Several efforts have been made to modify zeolite membranes in order to enhance their capability in gas separation by ion exchange process. Here, investigations were performed on the ion exchange process of zeolite NaY membrane with Ag+ cation at different concentrations (0.1M, 0.025M) and temperatures (ambient temperature and 80°C). The results revealed that temperature plays significant role in maintaining the morphologies of zeolite NaY membranes. Dealumination process was also observed to occur simultaneously with the ion exchange process. Overall, CO2/CH4 selectivity of the cation-exchanged NaY zeolite membranes increased by 100% with less CO2 flux reductions were recorded by samples which had been ion exchanged with less concentrated ion exchange solution i.e. 0.0125M at ambient temperature. Nevertheless, CO2/CH4 selectivity decreased for membrane samples which had been ion exchanged at higher temperature (80°C) due to dissolution of the zeolite membranes layer.