Effect of microwave heating on the performance of catalytic oxidation of n-butane in a gas-solid fluidized bed reactor

Abstract

Catalytic oxidation is widely acknowledged as the most promising technology for the conversion of hydrocarbon feedstocks to a variety of bulk industrial chemicals. The formation of undesired by-products through secondary gas-phase reactions has been underscored as the limiting step for this technology. In this study, microwave heating is proposed to challenge the evolution of undesired by-products based on the exclusive selective heating mechanism. This task is accomplished through a significantly higher solid (as microwave receptors) temperature compared to the gas phase temperature according to the principles of microwave irradiation approach. In order to highlight the influence of microwave heating on the overall performance of a gas-solid fluidized bed reactor, a simulation study was attempted for a model reactive system. Thus, catalytic oxidation of n-butane over the fluidized vanadium phosphorous oxide catalyst to produce maleic anhydride was selected as the model reaction. The bed hydrodynamics was described by a dynamic two-phase flow model while a kinetic model, adopted from the available literature, represented the reaction feature of the reactor. The original experimental data from a lab-scale microwave-heated fluidized bed reactor and the respective energy balance modeling were employed to describe the temperature distribution between bulk, solids, and gas segments of the simulated bed for the microwave heating scenario. The simulation study indicated that when competitive gas and solid phase reactions are occurring in a gas-solid fluidized bed reactor, the application of microwave selective heating approach can significantly enhance the overall performance of the reactor in comparison with the conventional heating, where solids, bulk, and bed temperatures are identical. Consequently, the application of microwave heating has been proposed as a promising approach to promote catalytic selective oxidation of hydrocarbons.