Improved hydrothermal stability of LTA zeolite membrane by forming an acrylamide protective layer for pervaporation dehydration of water-rich acrylamide and ethanol solutions

It is a great challenge to maintain the hydrothermal stability of LTA zeolite membrane in pervaporation (PV) dehydration of water-rich solutions at high temperatures. In this work, high selective LTA zeolite membranes fabricated on coarse alpha-alumina supports were successfully applied for dehydration of water-rich acrylamide (AM) solutions. For dehydration of a 70 wt% AM/H2O solution at 353 K, the LTA zeolite membrane exhibited incredibly superior hydrothermal stability for running 240 h. The membrane exhibited a superb permeation flux of 7.96 kg m- 2 h-1 and a high separation factor of more than 3800. The mechanism of stable existence of membrane crystals in the water-rich solutions was further investigated in detail. The results demonstrated that AM dynamically formed a new protective layer on LTA zeolite membrane surface, which effectively inhibited the degradation of zeolite crystals by high-temperature water. Importantly, the application of LTA zeolite membrane in the separation of other water-rich solutions could be further expanded by adding a small amount of AM. This study provides a new and simple method to improve the hydrothermal stability and application of LTA zeolite membranes in water-rich solutions at high temperature, which could expand the scope of industrial application and extend membrane lifetime.