Mordenite Membranes: Preparation, Modification And Their Pervaporation Performance

Zeolite membrane is an important class of inorganic membranes. Zeolite membrane can be used in a wide variety of applications such as catalysis and separation processes due to their high thermal resistance, chemical inertness, high mechanical strength as well as their unique pore system. In this work, we investigated the preparation, chemical modification and pervaporation performance of mordenite membranes, as discussed below:1. Mordenite membranes were prepared on the outer surface of tubular alpha-alumina supports using seeded hydrothermal synthesis and evaluated for the separation of a water/ethanol mixture by pervaporation. The influence of seeding on the pervaporation performance of mordenite membranes was investigated. It was found that the amount of seeds on the support surface was an important factor to reproducibly obtain mordenite membranes with good water/ethanol separation factors. Mordenite membranes grown on the supports that were dip-coated on the diluted seed suspension (0.02 g L^-1) showed better pervaporation performance and reproducibility than those grown on the supports that were dip-coated in the concentrated seed suspensions (2.0 g L^-1 and 0.2 g L^-1).2. The effect of post-treatmentwith hydrochloric acid solution was studied on the pervaporation performance of mordenite membrane. It was demonstrated that the water/ethanol separation factor could be effectively improved upon post-treatment with hydrochloric acid under controlled conditions. Compared with the as-synthesized membranes, the mordenite membranes prepared via this technique are more water-selective and of high stability in an acidic environment, which broadens the application fields of the mordenite membranes.3. The effect of post-treatment with oxalic acid was investigated on the pervaporation performance of mordenite membranes for the separation of a water/ethanol mixture. It was demonstrated that the water/ethanol separation factors were enhanced from 6-44 to higher than 10000 after as-synthesized mordenite membranes were hydrothermally treated in an oxalic acid solution under appropriate conditions.4. The use of mordenite membrane to separate an equal molar binary p-/o-xylene mixture by pervaporation was investigated. For pure o-xylene and p-xylene, p-xylene permeates faster than o-xylene through mordenite membranes. For the p-/o-xylene mixture, o-xylene permeates faster than p-xylene.