Synthesis of a Ni-containing porous SiOC material from polyphenylmethylsiloxane by a direct foaming technique

Idesaki, Akira; Colombo, P.*

A Ni-containing porous silicon oxycarbide (SiOC) material was synthesized from a blend of polyphenylmethylsiloxane (PPMS), azodicarbonamide and nickel(II) acetylacetonate by a direct foaming technique. Homogeneous foaming of PPMS with well-controlled macropore size distribution in the range of 0.1-0.5 mm was achieved, by controlling parameters such as the composition of starting mixture, the heating rate and the sample aspect ratio. A porous SiOC material with metallic Ni was obtained by pyrolysis below 900C in Ar. However, open porosity of the obtained porous SiOC was about only 37%. Therefore, the addition of fillers or an extraction treatment process were examined in order to obtain high levels of open, interconnected porosity. It was found that the extraction treatment of foamed PPMS by ethanol is effective in producing highly open porous SiOC ceramics. The Ni-containing porous SiOC material synthesized by this treatment possessed an open porosity of about 70% and gas permeability constant of 4.1010 for Darcian permeability constant and 3.1710 for non-Darcian permeability constant. These values are sufficiently high for its application as a catalyst material. According to the results above, the synthesis of a Ni-catalyst supported on a porous SiOC ceramic by a simple one-pot process was demonstrated.