Synthesis regularity of NaA zeolite membrane in microwave field

Zeolite membrane has the potential advantages in a number of applications such as separation and catalysis, chemical sensors, electrode, acoustic wave devices and optics devices. The paper reports a novel method for continuous NaA zeolite membrane deposited on porous aluminum substrate by microwave heating at ambient pressure and under reflux. The effects of placement manners, alkalinity, Na+ concentration and synthesis times on zeolite membrane formation were investigated. XRD and SEM results show that high alkalinity and high Na+ concentration don't benefit to form continuous membrane, whereas dissolve membrane layer. Among three placement manners, vertical placement and horizontal placement manners show better effects on zeolite membrane formation. In order to improve membrane quality, employing multi-stage synthesis is necessarily, which is prone to restrain transformation of NaA zeolite and increases intergrown degree of membrane in gel reactant system for short synthesis time.