A novel method for the synthesis of Silicalite-1 membrane: counter diffusion secondary growth

摘要

Silicalite-1 membranes on macroporous alumina tubes were prepared by a novel method called counter-diffusion secondary growth (CDSG), which was different from the conventional methods by having two sides of the support wall contact with two different precursors which would react when they encountered with each other. Silicalite-1 crystals with sizes of 300-400 nm, 600-800 nm and 1600-1800 nm were coated on the supports as seeds. Tetraethyl orthosilicate (TEOS) and tetra-propyl ammonium bromide (TPABr) were used as silicon source and template in the CDSG process, respectively. XRD, SEM and single-gas permeation tests were used to Characterize the final membranes. Results showed the as-prepared membranes were typical Silicalite-1 membranes with well morphologies. The hydrogen permeance and H2/SF6 ideal separation factor of the membrane prepared by optimized conditions were up to 7.5×10 -7 mol·m -2 · s -1 ·Pa -1 and 103, respectively, at room temperature under a pressure drop of 0.1 MPa.