Preparation Of Silicalite-1 Membranes And Its Separation Performances Towards Alcohol/water Mixtures

In this paper, high-performance and high-reproducibility silicalite-1 membranes were synthesized on porous silica tubes and alumina tubes. The effects of different hydrothermal synthesis conditions on the separation performance of silicalite-1 membranes were systematically investigated. By using two-step in-situ hydrothermal synthesis method, silicalite-1 membrane prepared on silica tube showed the highest flux of 0.99 kg/m2·h and separation factor of 73 towards EtOH/H2 O mixture at 60℃, while for the membrane synthesized on alumina tube at the optimal synthesis conditions, the flux and separation factor were 1.38 kg/m2·h and 62, respectively.As shown of the pervaporation, all the membranes showed high separation performance towards EtOH/H2 O mixture after synthesizing the membranes under the optimal synthesis conditions, and all the silicalite-1 membranes can concentrate the ethanol from 3% in the feed to above 60% in the permeation side with the average flux of 0.86 kg/m2·h and separation factor of 67, which showed high potential industrial applications.In order to pretreat the porous supports effectively, organics carbonization filling method was used preliminary to improve the separation performance of the as-synthesized silicalite-1 membranes. After filling the alumina tubes, the fluxes of 4 silicalite-1membranes were above 1.2 kg/m2·h with the separation factor of above 50. In order to improve the separation performance of silicalite-1membranes, carbon sedimentation method was used to modificate the membrane surface. The separation data showed that the separation selectivity can be improved effectively, but the membrane flux decreased. Therefore, a suitable filling method could be of significance for effectively improving the separation performance of silicalite-1 membranes.