Nanocatalysis: Selective Conversion of Ethanol to Acetaldehyde Using Mono-atomically Dispersed Copper on Silica Nanospheres

Silica nanospheres, d∼30 nm, are prepared at elevated temperature from an Si/SiO2 mixture. Under ambient conditions, the high population of surface hydroxyl on these nanospheres, confirmed by FTIR spectroscopy, is probed by decorating the surfaces of the spheres with the metal complex copper (II) acetylacetonate: Cu(acac)2. This metal complex, known to be anchored by the surface SiOH species, is converted into the active catalyst by thermolysis of the ligands. The resulting monatomic copper distribution forms a selective catalyst whose conversion efficiency appears to be at least comparable to if not better than CuO/fumed silica. In contrast to the fumed silica, the preparation of this catalyst support is environmentally benign.