Catalytically functionalized ceramic foams for exhaust gas treatment

High open porosity, network-like structure and high surface-to-volume ratio make open-celled ceramics attractive as catalyst supports. Compared to conventional honeycomb supports or fixed beds made of pellets they can provide low pressure drop at high space velocities, good heat transport as well as good lateral mixing of reaction gases. Despite many papers on the use of ceramic foams in reaction engineering have been published since 1995, ceramic foams are not widely used in real industrial applications in this field. An interesting additional property of ceramic foams for the application in heterogeneous catalysis for exhaust gas treatment is the interaction with microwaves. Due to their open structure, they provide a high degree of microwave penetration. But depending on the type of cer amics, their interaction can range from local high absorption at the struts to nearly complete transparency. In this work the catalytic combustion of waste gases from industrial processes was examined, to comply with legal regulations. Ceramic foams with different cell sizes made of different types of silicon carbide and cordierite were produced and characterised regarding their heating behaviour in microwaves. They were coated homogeneously by a special dip/spincoating procedure in a one shot process with thin layers of a mixed oxide catalyst. Their interaction and off-gas cleaning behaviour was measured using external heating as well as microwave heating.