Automatic measurement and analysis of kinetics for photocatalytic reactions in continuous microflow

As photocatalysis has been demonstrated to be a powerful tool for chemical synthesis over the last decades, it is essential to acquire reaction kinetics and kinetic model for the implementation of photocatalytic reactions. However, traditional kinetic study for photocatalytic reactions has problems including low accuracy, repeatability and efficiency in measurement, and difficulty in controlling the reaction conditions. Herein, we report an automatic continuous microflow platform for kinetics measurement and analysis of homogeneous photocatalytic reactions, with accurate control of reaction conditions (species concentrations, light intensity and residence time), efficient online measurement and sophisticated data analysis. Via the automatic platform, the rate law for the homogeneous photocatalysis of 9,10-diphenylanthracene (DPA) was acquired by investigating 70 different reaction conditions in 14 h, from which the reaction orders with respect to light intensity, photocatalyst concentration and substrate concentration were determined as 0.62, 0.82 and 1.00, respectively. Subsequently, a reaction rate constant independent of species concentration, light intensity and residence time was derived (with a value of 1.00). By doing so, reaction kinetics and the influence of multiple factors manifested in the as-derived rate law in a direct and concise manner. Furtherly, the as-obtained rate law was demonstrated to make good predictions on reaction kinetics, with an average of relative deviations of 3.18%, even for a range of new reaction conditions extending that used to obtain the rate law. The automatic kinetics measurement and analysis platform and the rate law incorporating the influence of multiple factors reported in this work can pave the way towards deeper understanding and faster implementation of homogeneous photocatalytic reactions.