Real-time monitoring of permeation properties through polycrystalline MFI-type zeolite membranes during pervaporation using mass-spectrometry

In this study, a system for the real-time monitoring (RTM) of pervaporation performances was developed to measure the permeation behaviors under the unsteady-state condition. By using a standard gas in combination with a mass spectrometer, the permeation behaviors during pervaporation could be simply, continuously, and sensitively monitored. By applying this system to a temperature-programmed pervaporation experiment, the effect of temperature on the permeation properties could be rapidly determined. In this study, the system was also used for monitoring the permeation behavior under the unsteady-state condition. As a result, the unique permeation behavior of water occurring early in the pervaporation experiments could be observed. This monitoring result suggests that the competitive adsorption, diffusion, and permeation routes of molecules are important for the permeation and separation performances of zeolite membranes.