Synthesis of silicalite-1 zeolite membranes for vapor-permeation separation of dichlorobenzene Isomers

Silicalite-1 zeolitic membranes have been successfully fabricated on the porous α-Al2O3 support by templated and template-free protocol, respectively, for vapor permeation separation of dichlorobenzene (DCB) isomers. After proving the high quality of the membranes by single gas permeation (He and SF6) performance, the vapor-permeation of DCB isomers over two types of the silicalite-1 membrane was then investigated. The separation results clearly indicated that under the lower partial pressure and higher temperature, the effect of DCB isomer adsorption on the permeance could be kept at a sufficiently low level and sharp selectivity become more important. Thus, high p-DCB selectivity could be achieved. Comparatively, the template-free silicalite-1 zeolite has a much higher p-DCB selectivity due to the relatively fewer inter-crystalline gaps. Under certain separation conditions, the highest selectivity of p-DCB for p-/m-DCB and p-/o-DCB binary systems could reach 165 and 113, respectively.