Preparation and characterization of SiC microtubes

Silicon carbide microtubes with medium surface area, 30–70 m2 g−1, were successfully prepared by shape memory synthesis involving the reaction between SiO vapors and low surface area, 1–2 m2 g−1, carbon microfibers. The gross morphology of the carbon microfibers was conserved during the carburization process. After calcination at 600°C in order to eliminate the unreacted carbon, hollow SiC microtubes were obtained. The pore size distribution of the material was centered around 10 nm, allowing a high accessibility of potential reactants to an active phase during catalytic reactions. The surface was covered by an amorphous layer 3 nm thick. XPS measurements revealed that this amorphous phase was composed of a mixture of SiO2 and SiOxCy. Soda treatment at 80°C allowed complete removal of this surface phase without any change in the material morphology. A similar result was also obtained after treatment with an aqua regia medium.