Titanium-microfiber-supported binary-oxide nanocomposite with a large highly active interface for the gas-phase selective oxidation of benzyl alcohol

Thin-sheet sinter-locked Ti-microfiber-supported binary-oxide-nanocomposite catalysts engineered on the micro- to macroscales were developed for the gas-phase aerobic oxidation of benzyl alcohol to benzaldehyde. The catalysts demonstrated higher activity than single-oxide and noble-metal catalysts with good stability and regenerability. The catalysts were obtained by placing transient metal (e.g., Ni, Co, Cu, Mn) nitrates onto a Ti-microfiber surface by impregnation, and the supported nitrates were subsequently in situ transformed into the binary-oxide composites in the real reaction stream at 300 °C. Among them, CoO-2.5-CuO_x-2.5/Ti-fiber was found to be the best catalyst; it delivered 93.5 % conversion of benzyl alcohol (b.p. 210 °C) with 99.2 % selectivity to benzaldehyde at 230 °C. In situ induced formation of "CoO@Cu₂O" ensembles (i.e., larger CoO nanoparticles partially covered with smaller Cu₂O clusters and/or nanoparticles) was identified, which by nature resulted in a large Cu₂O-CoO interface and led to a significant improvement in the low-temperature activity. Avoiding the heat: A Ti-microfiber-supported binary-oxide catalyst of the type CoO-Cu₂O/Ti-fiber with CoO@Cu₂O ensembles is designed and tailored for the gas-phase aerobic oxidation of benzyl alcohol to benzaldehyde. The catalyst exhibits higher low-temperature activity than single-oxide and noble-metal catalysts and shows good stability and regenerability.