Preparation of chabazite zeolite membranes by a two-stage varying-temperature hydrothermal synthesis for water-ethanol separation

Abstract

Pure and thin chabazite zeolite membranes were successfully prepared on macroporous symmetrical stainless steel supports by a two-stage varying-temperature hydrothermal synthesis. The morphologies and pervaporation properties of chabazite zeolite membranes were greatly influenced by synthesis times and temperatures at each stage. XRD and SEM characterization results showed that a high temperature at the first stage could effectively avoid the formation of MER impurity phase. The optimal crystallization condition was 150 °C for 10 h at the first stage and 100 °C for 5 h at the second stage. Pervaporation results presented that the precursor gel containing a certain amount of chabazite seed crystals was beneficial to prepare high-performance chabazite zeolite membranes. Well reproducible chabazite zeolite membranes displayed an average permeation flux of 6.25 kg m−2 h−1 and an average separation factor of 1950 for a water/ethanol (10/90 wt%) mixture at 75 °C. Besides, as-synthesized membranes had a good stability for separation of a water/ethanol (30/70 wt%) mixture at 75 °C for 10 d test period, indicating that chabazite zeolite membranes had a promising dehydration application even in water-rich organic solvents.