Heterogeneous nitration of nitrobenzene in microreactors: Process optimization and modelling

Abstract

Aromatic nitration with mixed acid is an important step in the industrial synthesis of basic industrial chemicals, while the highly exothermic and heterogeneous nature of the reaction renders difficulties in achieving high safety and efficiency. In this work, a continuous flow microreactor system was developed for the nitration of nitrobenzene. Under the premise of high conversion and selectivity, the reaction time and temperature were reduced from more than 2 h and 80 ℃ in industrial operation to 10 min and 65 ℃ in microreactors, respectively. The reaction mechanism was verified that the reaction took place not only in the bulk aqueous phase but also at the phase interface. The kinetic parameters were then determined based on the assumption of pseudo-homogeneous reaction mixture. These findings may shed important insights into the high degree of controllability of nitration for a better process design and reactor optimization.