Polymerization of polycarbosilanes in high internal phase emulsions for the synthesis of macroporous silicon carbidecatalysts (polyHIPE-SiC)

Abstract

A new method for the preparation of macroporous silicon carbide using a polyHIPE approach is presented (polyHIPE = polymerized High Internal Phase Emulsion). A liquid preceramic precursor is copolymerized with styrene and the crosslinker divinylbenzene in different ratios and two different initiators. The resulting PCS-co-Sty-co-DVB-polyHIPEs are pyrolysed at 1300 °C under argon atmosphere. Macroporous SiC-polyHIPEs are formed with specific surface areas up to 167 m² g⁻¹. Mercury porosimetry shows the presence of macropores with a pore radius between 200 and 2000 nm and total porosities between 36 and 94%. One SiC-polyHIPE is functionalized with cerium nitrate to form CeO₂-SiC-polyHIPEs with varying ceria contents. These SiC-supported ceria show catalytic activity in the temperature programmed oxidation of methane, lowering the onset temperature by 366 K.