Optimisation of greener and more efficient 1,7-octadiene epoxidation catalysed by a polymer-supported Mo(vi) complex via response surface methodology

Abstract

In this study, a greener and more efficient alkene epoxidation process has been developed using a heterogeneous polybenzimidazole supported Mo(VI) catalyst and tert-butyl hydroperoxide (TBHP) as an oxidising reagent. Polybenzimidazole supported Mo(VI) complex, i.e., PBI·Mo has been prepared, characterised, and evaluated successfully. Batch epoxidation experiments have been carried out in a jacketed stirred batch reactor to evaluate the catalytic activity and stability of PBI·Mo catalyst for the epoxidation of 1,7-octadiene. The suitability and efficiency of the catalyst have been compared by studying the effect of four independent factors such as reaction temperature, the feed mole ratio of 1,7-octadiene to TBHP, catalyst loading, and reaction time on the yield of 1,2-epoxy-7-octene for optimisation of reaction conditions. Response surface methodology (RSM) using Box–Behnken design (BBD) was employed for designing experimental runs and studying the interaction effect of different variables on the reaction response. A quadratic regression model has been developed representing an empirical relationship between reaction variables and response. To determine the adequacy of the predicted model, numerous statistical validation techniques including analysis of variance (ANOVA) have been applied at a 95% confidence level. The numerical optimisation technique concluded that the maximum yield that can be reached is 66.22% at a feed molar ratio of 7.97 : 1, reaction temperature of 347 K, 0.417 mol% catalyst loading, and reaction time of 218 min. The predicted optimal conditions have been validated experimentally with a 1.92% relative error.