Structural Evolution during Conversion of Polycarbosilane Precursor into Silicon Carbide-Based Microporous Membranes

Abstract

Silicon carbide-based microporous ceramic membranes for hydrogen separation were prepared via pyrolysis of polycarbosilane as a polymeric precursor. To prepare membranes with excellent hydrogen separation performance, effects of hydrosililation cross linking, addition of thermally-labile polymer as well as pyrolysis conditions on the structural evolution during conversion of the polycarbosilane precursor into the silicon carbide-based microporous membranes, have been investigated. The results of the activation energy for possible reactions, change in functional groups, and nitrogen adsorption and gas permeance measurements suggested that the cross-linking reaction between triple bond and Si-H bond gave three dimensional networks, resulting in smaller micropore and larger surface area. The size of the gases evolved during pyrolysis was also suggested to have relationship with the micropore structure.