Electro-oxidation of benzyl alcohol to benzaldehyde in supercritical CO_2 with ionic liquid

摘要

Electro-oxidation of benzyl alcohol (BA) to benzaldehyde was conducted in homogeneous supercritical CO_2/[Bmim][PF_6]/MeCN solutions. The study of cyclic voltammetry indicates that electro-oxidation of BA in the solutions is an irreversible reaction, oxidation peak appears at a voltage of 2.7 V, and the electro-oxidation of BA is a diffusion-controlled process. Electrolysis potential, electric quantity, and pressure of the reaction system have great influences on conversion of BA, selectivity towards benzaldehyde, and Faradic efficiency. High selectivities and yields of benzaldehyde can be obtained by tuning electrolysis conditions. Our results have demonstrated that both the selectivity and the yield of benzaldehyde can reach higher than 99.8% at an electrolysis potential of 2.7 V, system pressures of 16-17 MPa and a temperature of 318.15 K.