Synthesis of micropore zeolite membranes with supercritical extraction method

Abstract

Synthesis of zeolite membrane was examined by the supercritical extraction method that is the template of zeolite being extracted with supercritical methanol and carbon dioxide mixtures. At first, ZSM-5 particles were synthesized with supercritical extraction method. The shape of zeolite particles remained itself after the supercritical extraction with methanol-carbon dioxide mixtures, whereas the particle was broken after the supercritical methanol only. The template was extracted above 250 ℃ with supercritical methanol-carbon dioxide mixture while no template was extracted with supercritical carbon dioxide carbon dioxide only, which means that the extraction of template was promoted with polar solvent such as methanol in addition to carbon dioxide. Next, ZSM-5/Silicalite composite membrane was synthesized by the supercritical extraction method with methanol-carbon dioxide mixtures. The hydrogen permeated through the membrane whose extraction temperature was above 200 ℃. The increase in extraction temperature increased the permeance. The permeance was significantly lower than the membrane obtained with calcinations of template. Further, the permeance of n-butane and isobutene for the membrane obtained with supercritical extraction method was different from those obtained with calcination of template. The supercritical extraction method for zeolite membrane achieved the formation of membrane containing a lot of template and this membrane shows distinctive properties such as permeance which was different from the membrane obtained with calcination of template.