A step toward the numerical simulation of catalytic hydrogenation of nitrobenzene in Taylor flow at practical conditions

Abstract

While computational studies on hydrodynamics of gas-liquid Taylor flow in microreactors are increasing, inclusion of mass transfer and reactions pose a challenge. Especially simulations for technically relevant reactions are lacking. This study undertakes a step in this direction by considering the hydrogenation of nitrobenzene to aniline. Physical properties are estimated from literature and a lack of data for practically relevant temperature and pressure is identified. By neglecting any feedback on hydrodynamics, the hydrogenation of nitrobenzene in a micro-channel is studied by two-dimensional numerical simulations with a volume-of-fluid method using a one-step reaction mechanism. Simulations are performed for three different bubble velocities at intermediate capillary numbers. Increase of bubble velocity enhances mass transfer and aniline production rate due to intensified recirculation in the liquid slug. Even for the channel height of 100 µm investigated here, the reaction is mass transfer limited and independent on initial concentration of hydrogen in liquid nitrobenzene.