Canadian Journal of Chemical Engineering, Vol.98, No.5, 1139-1147, 2020
Determination of kinetic parameters of homogenous continuous flow esterification of monobutyl chlorophosphate in a microreactor
Synthesized by phosphorus oxychloride and n-butanol, tri-n-butyl phosphate from a three-step esterification reaction has an extensive range of applications in industrial processes. Similarly, monobutyl chlorophosphate can be obtained rapidly by mixing n-butanol and phosphorus oxychloride. In view of this, we investigated the kinetics of esterification of monobutyl chlorophosphate with a microchannel system composed of micromixer and coiled capillaries. The reaction started from mixing the phosphorus oxychloride solution and n-butanol solution in a micromixer, with temperature and residence time in a delayed loop controlled, and then quenching the solution in a container with magnetic agitation. The rate constants for the esterification reaction of monobutyl chlorophosphate were determined to be within a temperature range of 298-318 K. It was found that the reaction kinetics is second order with respect to monobutyl chlorophosphate concentration and first order to n-butanol concentration. In our research, a kinetic model was established, the values of the pre-exponential factor and the activation energy of the reaction were obtained. The reaction kinetic model can interpret the synthesis mechanism of phosphate esters well, thus playing a guiding role in process intensification of phosphate esters synthesis in the future. Additionally, our model is also valuable because it contributes to the establishment of a reaction kinetics network model for the cascade reaction to synthesize phosphate esters.