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.

Automated summary

This study successfully fabricated high selective LTA zeolite membranes and demonstrated their excellent hydrothermal stability and separation performance in the dehydration of water-rich acrylamide solutions. The results revealed that acrylamide could form a protective layer on the membrane surface, effectively inhibiting the degradation of zeolite crystals by high-temperature water. Furthermore, the application of LTA zeolite membrane in the separation of other water-rich solutions could be expanded by adding a small amount of acrylamide.