Towards more efficient hydroformylation of long-chain alkenes in aqueous biphasic system using microbubbles

Microbubbles were applied for the first time to enhance the aqueous biphasic hydroformylation of long-chain alkenes. The gas–liquid–liquid multiphase hydroformylation was carried out using 1-dodecene as model higher olefin and dihexadecyl dimethyl ammonium bromide (DDAB) as surfactant. The increasing liquid temperature resulted in the increased mean bubble size and total bubble number, but this trend became inapparent at high temperatures due to the reduced liquid viscosity. The increasing gas flow rate was favorable to increase the multiphase interfacial area, thus leading to the increasing mass transfer coefficient K L a . The conversion of 1-dodecene reached maximum 95% in the three-phase microemulsion system, and at a gas flow rate of 40 ml min −1 . Further increasing the gas flow rate to 80 ml min −1 decreased the conversion, which was attributed to the destroyed flow field, as observed in micro-PIV. Owing to the increased multiphase mass transfer efficiency, the application of microbubbles allowed to intensify the hydroformylation reaction with reduced reaction pressure, higher chemoselectivity, and increased turnover frequency (TOF).