Mass transfer intensification and kinetics of o-xylene nitration in the microreactor

Continuous-flow synthesis of nitro- o -xylene has been widely reported. However, critical scientific challenges remain unresolved, including product selectivity optimization, process economic viability, and operational safety. Herein, continuous-flow o -xylene nitration with mixed acid in a capillary microreactor is presented. A kinetic model of the pseudo-homogeneous nitration reaction was developed, and the mass transfer process was characterised by the first Damköhler number and Hatta number. Notably, the capillary microreactor exhibited limited mass transfer efficiency, restricting conversion enhancement. To address this, a heart-shaped channel plate was integrated into the micro-reaction system. Under the M-ratio of HNO 3 to o -xylene was 3, residence time was 35 s, temperature was 303 K, the conversion rate of 100 % was achieved. The developed micro-reactor system significantly improved both the selectivity and conversion of o -xylene nitration, demonstrating substantial potential for industrial application.