(695b) Preparation of Silicon Carbide Membranes Using Nanoporous Fillers

Elyassi, B., University of Minnesota
Sahimi, M., University of Southern California
Tsotsis, T. T., University of Southern California

The increased interest in the efficient production of hydrogen, and in environmentally-benign power generation, is driving current development efforts on the preparation of nanoporous, hydrogen-permselective, inorganic membranes which can be used in processes that take place at high temperatures and pressures. Due to many unique properties, such as high oxidation resistance and hydrothermal stability, silicone carbide (SiC) is a promising membrane material for such applications in harsh environments.

Previously, we used slip casting of SiC powders on tubular SiC supports to reduce defect propagation from support into the membrane layer [1,2]. However, the SiC particles used were nonpermeable. The idea of the present work is to replace the nonpermeable SiC particles with permeable structures, and to investigate their effect on the membrane performance.

To do so, using a template technique, nanoporous SiC nanofibers with high surface area were prepared and used in the slip casting solution. The supports were slip casted in a solution of nanofibers and the pre-ceramice polymer, allyl-hydridopolycarbosilane (AHPCS). Using a sacrificial interlayer based method that we recently developed [1], additional layers of the AHPCS and sacrificial polystyrene were coated on the slip-casted support and, then, the entire structure was pyrolyzed at 750 oC for 2 h. The membrane results obtained with these materials and technique are compared with those obtained the previous method in which we used nonpermeable SiC powders for slip casting.

1. B. Elyassi, M. Sahimi, T.T. Tsotsis, A novel sacrificial interlayer-based method for the preparation of silicon carbide membranes, Journal of Membrane Science, 316 (2008) 73-79.

2. B. Elyassi, M. Sahimi, T.T. Tsotsis, Silicon carbide membranes for gas separation applications, Journal of Membrane Science, 288 (2007) 290-297.