Tailored Macroporous SiCN and SiC Structures for High‐Temperature Fuel Reforming

Abstract The catalytic reforming of hydrocarbons in a microreformer is an attractive approach to supply hydrogen to fuel cells while avoiding storage and safety issues. High‐surface‐area catalyst supports must be stable above 800 °C to avoid catalyst coking; however, many porous materials lose their high surface areas below 800 °C. This paper describes an approach to fabricate macroporous silicon carbonitride (SiCN) and silicon carbide (SiC) monoliths with geometric surface areas of 10⁵ to 10⁸ m² per m³ that are stable up to 1200 °C. These structures are fabricated by capillary filling of packed beds of polystyrene or silica spheres with low‐viscosity preceramic polymers. Subsequent curing, pyrolysis, and removal of the spheres yielded SiCN and SiC inverted beaded monoliths with a chemical composition and pore morphology that are stable in air at 1200 °C. Thus, these structures are promising as catalyst supports for high‐temperature fuel reforming.