Recent Progress in Zeolite/Zeotype Membranes

This is a comprehensive review of the recent progresses made in the field of zeolite membranes. It describes zeolitic materials and methods of membrane fabrication, followed by a summary of applications for gas separation, pervaporation and separation of liquid mixtures. Special attention is called to polymer mixed matrix membranes (MMMs) and membranes based on metal organic frame works (MOFs). In this comprehensive survey, the following trends were observed during the past 5 – 10 years. New zeolitic materials and new synthesis methods, such as hydrothermal synthesis, seeding and microwave heating, have been continuously reported in the literature. Many efforts have been devoted to the synthesis of hybrid or mixed matrix membranes (MMMs) since MMMs clearly outperformed polymeric membranes. MOFs also showed improved performance in gas separation. Many attempts have been made to develop thin (1µm) supported zeolite layers on a variety of carriers such as capillaries, fibers, tubes, etc. The assembly of nanozeolite building blocks and nanosheets is the starting point for the synthesis of thin defect free zeolite membranes. The present review presents the recent progresses made in the field of zeolite/zeotype membranes. Different types of zeolite membranes, methods of preparation and application aspects especially for separation of gases have been focused on, including the individual zeolites which are in use or are to be used as inorganic fillers in mixed matrix membranes (MMMs). Despite the enormous efforts of researchers, the commercialization of zeolite membranes has been achieved only in a limited area. The future works necessary to change the current situation are hence suggested.