Tailored Surface Properties of Ceramic Foams for Liquid Multiphase Reactions

Open cellular ceramic foams are prepared using the replica method. In a second step, these foams are coated with a pre‐ceramic or polymer‐derived ceramic coating, respectively. Polymer‐to‐ceramic transformation is studied by SEM with respect to the microstructure, functional groups are characterized by Raman microscopy, density and porosity are determined by pycnometer measurements as well as the surface free energy by means of contact angle measurements. By pyrolysis at different temperatures between 403 and 1273 K, the surface wettability is adjusted in a wide range from hydrophilic to hydrophobic due to the release of organic groups from the pre‐ceramic polymers in terms of polymer‐to‐ceramic transformation. Coated foams are tested in a new potential application: as reactor internals to increase the liquid–liquid interface area in a homogeneously catalyzed multiphase system. As model reaction, a reactive extraction of an organic dye was used and the influence of the surface energy of the foam on the phase dispersion/reaction rate is discussed. The coated foams are able to increase the reaction rate to an extent depending on the surface wettability.