Tuning the Si/Al ratio in CHA zeolite membranes for highly efficient dehydration of acetic acid by vapor permeation

Abstract Vapor permeation (VP) represents an energy‐efficient separation technology for acetic acid dehydration, characterized by minimized salt fouling and enhanced flux. However, this technique imposes stringent requirements on membrane materials regarding acid resistance and hydrophilic properties. In this work, the silicon‐to‐aluminum ratio (SAR) of chabazite (CHA) zeolite membranes was precisely regulated from 3.8 to infinite for VP separation of a water/acetic acid mixture for the first time. Membrane stability was evaluated based on separation performance and comprehensive characterization techniques, including scanning electron microscopy, x‐ray diffraction, and energy dispersive x‐ray analyses before and after VP testing. Single‐gas permeation and the effects of operation parameters (temperature, feed concentration, and flow rate) were systematically investigated. At 413 K, a typical high‐silica CHA zeolite membrane achieved superior separation performance: water flux of 9.34 kg m−2 h−1, water permeance of 7.08 × 10−7 mol m−2 s−1 Pa,−1 and selectivity of ~1000 in a 30/70 wt% water/acetic acid mixture, surpassing that of reported membranes.