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

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 10 5 to 10 8 m 2 per m 3 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.

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