Effects of synthesis parameters on the zeolite membrane morphology

The effects of synthesis parameters (i.e. [TEOS], [TPA(+)], [OH-] and dilut ion) on membrane surface morphology is investigated for zeolite membranes g rown on seeded supports (i.e. porous glass and alumina). Microstructural pa rameters including crystal size (d) and shape (M), apparent surface porosit y (R-a) and average grain boundary (G) are used to quantify the membrane su rface morphology. An empirical model that relates the length (l) and width (w) of the grain facets to the synthesis variables is derived based on the experimental data. The model gives an adequate description of membrane surf ace morphology and provides guidance for the synthesis of zeolite membranes with engineered microstructure. Helium, argon and sulfur hexaflouride gase s are used as molecular probes to investigate zeolite membranes with differ ent grain sizes (i.e. 0.6-1.1 mum) and grain morphologies (width-to-length ratio, M = 0.15-0.95). The single gas permeation experiments demonstrate th at micro-scale structural property, such as zeolite grain size and morpholo gy can affect the transport properties of the membrane. This work represent s an initial step towards the rational design of engineered zeolite membran es for separation applications. (C) 2001 Elsevier Science B.V. All rights r eserved.