First use of macroporous silicon loaded with catalyst film for a chemical reaction: A microreformer for producing hydrogen from ethanol steam reforming

Macroporous silicon with millions of parallel microchannels per square centimeter can be used as a micromonolithic support for high-speed catalysis in miniaturized systems, opening a new and exciting field of research and application. We used macroporous silicon membranes with >106 parallel microchannels with a diameter of 3.3 μm and depth/width ratio >60 as microreactors for the generation of hydrogen through the steam reforming of ethanol. The microchannels walls were coated with a thin layer of Co3O4–ZnO catalyst by a complexation–decomposition method, resulting in a specific inner surface of 105–106 m2 m−3. A constant flow of 20 μL s−1 H2 (0.054 mmol min−1 H2) was obtained from a liquid water–ethanol mixture at 773 K with a steam-to-carbon ratio of S/C = 3 and LHSV = 2 × 104 h−1 (0.1 mL min−1). The turnover frequency under these conditions was ca. 1.1 s−1, based on surface Co atoms.