Development of high-performance sub-nanoporous SiC-based membranes derived from polytitanocarbosilane

The separation of azeotropic mixtures such as methyl acetate and methanol via a membrane is an interesting and challenging issue, since the membrane must be able to withstand these harsh solvents and provide good flux and selectivity. SiC-based membranes have attracted a great deal of interest due to their high mechanical strength, structural stability, and corrosion resistance at elevated temperatures. Herein, we describe the first use of polytitanocarbosilane (TiPCS), which is known as a precursor of continuous Si-Ti-C-O fibers (Tyranno), in the preparation of Ti-incorporated SiC-based membranes for the pervaporation (PV) removal of water or methanol, and describe the evaluation of hydrothermal stability. For this study, the physical and chemical properties of TiPCS-derived materials during pyrolysis were characterized via TG-MS, ATR-FTIR, XPS, XRD, and N-2 adsorption-desorption isotherms. The pore characteristics and surface areas of TiPCS-derived ceramic powders revealed that the titanium components in TiPCS inhibit and/or reduce the densification of the network structures at elevated temperatures. The network structure of TiPCS-derived, SiC-based membranes showed trends similar to those of TiPCS-derived ceramic powders. The membrane prepared at 750 degrees C featured reproducibility and attractive selectivities for the PV removal of water or methanol from liquid mixtures.