Mechanism and kinetics of the aerobic oxidation of benzyl alcohol to benzaldehyde catalyzed by cobalt porphyrin in a membrane microchannel reactor

• Published in: Chemical engineering science Vol. 245; p. 116847
• Main Authors: Han, Qi, Zhou, Xian-Tai, He, Xiao-Qi, Ji, Hong-Bing
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 14.12.2021
• Subjects: Benzyl alcohol; Cobalt porphyrins; Kinetics; Mechanism; Membrane microchannel reactor; Oxidation; Membrane microchannel reactor; Oxidation; Benzyl alcohol; Kinetics; Cobalt porphyrins; Mechanism
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2021.116847

[Display omitted] •Benzyl alcohol oxidation was achieved in a membrane microchannel reactor.•Mechanism involving free radical and high-valence species was demonstrated.•Benzyl alcohol oxidation exhibited the features of Michaelis–Menten kinetics. The highly efficient selective aerobic oxidation of benzyl alcohol to benzaldehyde catalyzed by cobalt porphyrin was achieved in a membrane microchannel reactor. The efficiency of benzyl alcohol oxidation was remarkably improved in the micro-structured chemical system, achieving a conversion and benzaldehyde selectivity of 82% and 98%, respectively, in 6.5 min. The classification and transfer of free radicals, as well as the oxygen-transfer mechanism, were determined by in situ EPR (electron paramagnetic resonance) and in situ UV–visible spectroscopy. Further kinetic studies revealed that the oxidation of benzyl alcohol follows the Michaelis–Menten kinetics, with Km = 0.133 mol/L.A mathematic kinetic model was proposed, and the kinetic model fitted the experimental data well. The mathematical model can predict the reaction process at a wide range of benzyl alcohol concentrations, which is beneficial for the process optimization and reactor design.