Reaction-Induced Self-Assembly of CoO@Cu 2 O Nanocomposites In Situ onto SiC-Foam for Gas-Phase Oxidation of Bioethanol to Acetaldehyde.

A high-performance SiC-foam-structured nanocomposite catalyst of CoO@Cu2 O (i.e., 50-100 nm CoO partially covered with ca. 10 nm Cu2 O) was engineered from nano- to macro-scales in one step for the high-throughput gas-phase aerobic oxidation of bioethanol to acetaldehyde. This special CoO@Cu2 O nanostructure shows much higher activity/selectivity than other binary metal-oxide assemblies such as CuOx &CoO nano-mixtures or inverse Cu2 O@CoO nanostructures. The catalyst was facilely but exclusively obtainable by in situ reaction-induced transformation of the respective metal nitrates supported on SiC-foam into the CoO@Cu2 O nanostructure in the reaction stream. It achieved 95 % conversion with 98 % selectivity under mild conditions and was stable for at least 150 h for a feed of 20 vol % ethanol (much higher than in the literature: 1-6 vol %) at a high EtOH weight hourly space velocity of 8.5 h-1 . Abundant Cu2 O-CoO interfaces and high stability of the CoO@Cu2 O nanostructure were responsible for the high activity/selectivity and promising stability in this reaction.