Zeolites are microporous crystalline aluminosilicates with molecular sieving capabilities (pore size < 1.3 nm).[1±3] The use of zeolite coatings on different supports (metal substrates, porous glass, ceramic honeycombs, mesoporous materials) has recently been proposed for catalysis, adsorption, and separation.[4±8] Open-cell ceramic foams [9±15] (connected pores in the 0.1±4 mm range) are gaining interest as zeolite carriers [11±15] due to their unique properties, for the development of new reactor concepts (monolithic, catalytic wall configurations) for technical catalytic and adsorption±separation processes. [15,16] Here we present, for the first time, a novel zeolite±ceramic composite material, with a bimodal (nano-, macroscale) pore system, obtained by coating the cell walls of microcellular polymer-derived ceramic foams (cell size~8 lm) with a thin, binder-free layer of MFI-type zeolite (Silicalite-1 and ZSM-5), produced by an in-situ conventional supported hydrothermal synthesis. To our knowledge, these materials represent the smallest microreactors/separators fabricated to date.Ceramic foams, with low thermal expansion coefficients and high thermal, mechanical, and chemical stability, are suitable as zeolite supports because they provide enhanced mass and heat transfer and a low pressure drop when compared to zeolite pellets used in fixed-bed reactors. [9,10] The fabrication of ceramic foams from preceramic polymers allows tailoring of the composition and morphology, and therefore of the final properties, of the porous material. [17,18] Very recently, [19,20] we fabricated mechanically stable ceramic microcellular [21,22] foams with a homogeneous interconnected porosity and an average cell size in the range of~1±100 lm, bulk density from 0.2±0.6 g cm
±3, and cell density from~10 7 ±10 12 cells cm ±3 . The starting materials were poly(methyl methacrylate) (PMMA) microbeads, acting as sacrificial template, and a COMMUNICATIONS
