Preparation and evaluation of thin ZSM-5 membranes synthesized in the absence of organic template molecules

Porous alpha -alumina supports with a pore size of 100 nm were seeded with colloidal TPA-silicalite-1 crystals with a size of 120 nm. The seeded suppo rts were calcined and treated in a synthesis solution free from organic tem plate molecules to form ZSM-5 films on the supports. According to SEM image s, the films were about 2 mum thick and no defects could be found on the as -synthesized membranes. Single gas permeation data was collected and good q uality membranes (defined as having a non-detectable permeance of SF6 after drying at 100 degreesC) were further evaluated using binary/ternary gas mi xtures. The selectivity for n-butane/i-butane had a maximum value of 17.8 a t 220 degreesC. Water was selectively separated from a helium-diluted vapor ized water/ethanol azeotrope with a maximum selectivity of 12.4. (C) 2001 E lsevier Science B.V. All rights reserved.