Fabrication of silicon carbide membranes on highly permeable supports

We have recently reported (Wangxue Deng, Xinhai Yu, Muhammad Sahimi, and Theodore T. Tsotsis, Highly permeable porous silicon carbide support tubes for the preparation of nanoporous inorganic membranes, J. Membr. Sci. 2014, 451, 192-204) on the preparation of highly permeable and mechanically strong porous SiC tubular supports via the pressureless sintering of β-SiC powders, for potential use in the fabrication of nanoporous SiC membranes. In the paper, the effect of the type of starting powders used and their composition, the sintering temperature and the amount of sintering aids utilized on the transport characteristics and the surface roughness of these supports were systematically investigated. These tubular SiC supports exhibit very high fluxes (a He permeance as high as ~6×10−5 mol m−2 Pa−1 s−1) compared to supports prepared previously by our group and others, and are also mechanically strong to withstand the pressure drops required in their use as membrane supports. In this study, we report on the use of these supports in the preparation of SiC nanoporous membranes. The task of preparing high-quality membranes using these substrates is made possible via the use of a technique that creates on the support an interlayer scaffold made of highly uniform SiC nano-powders, followed then by the deposition of the SiC precursor layers. Utilizing these newly developed highly permeable, yet mechanically strong, silicon carbide supports, nanoporous silicon carbide membranes were fabricated, with permeances which are an order of magnitude higher than membranes prepared with less permeable supports but with comparable separation characteristics.