Abstract
A composite ceramic membrane was synthesised in situ by forming a layer of pure zeolite on a ceramic disk as substrate. Analysis with XRD, SEM, and optical microscopy reveal pure silicalite crystals which have intergrown into a dense, thin film. After calcination, the permeability of N2 is 1-4 cubic m/square m -hr -bar at 20 Grad C. The ideal selectivity, calculated from the ratio of single gas permeabilities, is 2.81 for He over N2, 47.7 for N2 over n-butane, and 6.2 for n-butane over i-butane, which are all well beyond the range of Knudsen diffusion. The influence of zeolite pores and defect pores on these results is briefly discussed. MacMillann