Hierarchically ordered foams derived from polysiloxanes with catalytically active coatings

Pt free and Pt containing hierarchically ordered macro/micro porous foams were generated by using polysiloxanes and platinic acid as precursors and expanded polystyrene beads as templates to generate macro pores. By pyrolysis at 500 °C micro porosity and thus high specific surface areas were generated. The foams were analyzed in terms of macro- and microstructures (SEM, micro-computer tomography, TEM, BET) and catalytic properties (CO oxidation). For the crack free foams a method was additionally developed that allows the application of a thin Pt-containing layer only on the cell walls. The well known problems arising from mass transport limitation in micro porous materials can be diminished due to the generation of thin struts and this minimized Pt coating on the cell walls as demonstrated by catalytic experiments.