Influence of synthesis gel composition on morphology, composition, and dehydration performance of CHA-type zeolite membranes

CHA-type zeolite membranes with excellent dehydration performance can be prepared on a porous α-Al2O3 support tube by the secondary growth of seeds in a synthesis gel containing strontium. The permeation flux and separation factor of the membrane were 2.89 kg m−2 h−1 and >100,000, respectively, for a 50 mol% ethanol solution at 313 K. In this work, the CHA-type zeolite membranes were prepared using the gel with different compositions to discuss the influences of the synthesis gel composition on the morphology, composition, and dehydration performance of the CHA-type zeolite membrane. As a result, the CHA-type zeolite membrane could be prepared in the gel with the following compositions: SiO2/Al2O3 = 2–16; H2O/SiO2 = 65–250; H2O/(K2O + SrO) = 100–400; SrO/(K2O + SrO) = 0.10–0.85. Furthermore, the CHA-type zeolite membrane was ion-exchanged with lithium, sodium, rubidium, and cesium ions, and the dehydration performances of the ion-exchanged membranes were also determined. Based on these results, the effect of strontium for the membrane preparation was discussed in this paper.