Reaction-Induced Self-Assembly of CoO@Cu₂O Nanocomposites In Situ onto SiC-Foam for Gas-Phase Oxidation of Bioethanol to Acetaldehyde

A high-performance SiC-foam-structured nanocomposite catalyst of CoO@Cu₂O (i.e., 50–100 nm CoO partially covered with ca. 10 nm Cu₂O) 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@Cu₂O nanostructure shows much higher activity/selectivity than other binary metal-oxide assemblies such as CuO_x&CoO nano-mixtures or inverse Cu₂O@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@Cu₂O 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 Cu₂O–CoO interfaces and high stability of the CoO@Cu₂O nanostructure were responsible for the high activity/selectivity and promising stability in this reaction.