Abstract:

In order to synthesize H₂O₂ in a green，sustainable，and convenient manner，the intensified study on the synthesis of H₂O₂ from benzyl alcohol （BA） under photoexcitation using a coiled flow inverter microreactor（CFIMR） was conducted.The effects of the residence time，light intensity，and cumulative residence time on the efficiency of H₂O₂ synthesis from BA under photoexcitation in the CFIMR photoreaction system were systematically investigated，and further optimization was carried out through methods such as reaction-extraction coupling and enhancement of gas-liquid two-phase flow.The results of the study showed that in the CFIMR，at the optimal single residence time of 50 s，the average synthesis rate of H₂O₂（r） was 0.563 3 mmol/（L·min）.Under the optimal irradiation conditions，when the cumulative residence time of the BA single phase reached 200 s，the concentration of H₂O₂ in the BA phase reached as high as 1.762 3 mmol/L.By introducing reaction-extraction coupling optimization techniques to simplify the process，r was 0.376 2 mmol/（L·min）.Under acidic conditions at pH=1.0，the highest r reached was 1.204 1 mmol/（L·min）.The r under the optimal H₂O/BA volume flow rate ratio was 0.458 0 mmol/（L·min）.Through the employment of gas-liquid two-phase flow intensification methods，the maximum value of r reached 0.883 2 mmol/（L·min）.In the CFIMR，the synthesis rates（r） of BA single-phase flow，H₂O-BA two-phase flow，and air-BA two-phase flow reached 151.06%，100.88%，and 236.85%，respectively，compared to conventional photoexcited BA synthesis of H₂O₂.It demonstrated the operational flexibility and high efficiency of photochemical synthesis of H₂O₂ inside the CFIMR，which was attributed to its high photon flux density and excellent mixing and mass transfer performance.

Key words: coil, microreactor, photochemical synthesis, H₂O₂, benzyl alcohol