The selective aerobic oxidation of benzyl alcohol to benzaldehyde has attracted considerable attention because benzaldehyde is a high value-added product. The rate of this typical gas–liquid reaction is significantly affected by mass transfer. In this study

CoTPP-mediated (CoTPP: cobalt (II)

meso

-tetraphenylporphyrin) selective benzyl alcohol oxidation with oxygen was conducted in a membrane microchannel (MMC) reactor and a bubble column (BC) reactor

respectively. We observed that 83% benzyl alcohol was converted within 6.5 min in the MMC reactor

but only less than 10% benzyl alcohol was converted in the BC reactor. Hydrodynamic characteristics and gas–liquid mass transfer performances were compared for the MMC and BC reactors. The MMC reactor was assumed to be a plug flow reactor

and the dimensionless variance was 0.29. Compared to the BC reactor

the gas–liquid mass transfer was intensified significantly in MMC reactor. It could be ascribed to the high gas holdup (2.9 times higher than that of BC reactor)

liquid film mass transfer coefficient (8.2 times higher than that of BC reactor)

and mass transfer coefficient per unit i

nterfacial area (3.8 times higher than that of BC reactor). Moreover

the Hatta number for the MMC reactor reached up to 0.61

which was about 15 times higher than that of the BC reactor. The computational fluid dynamics calculations for mass fractions in both liquid and gas phases were consistent with the experimental data.