Intensification of catalytic oxidation with a T-junction microchannel reactor for deep desulfurization

In this paper, a microreactor system is developed to enhance the oxidation of dibenzothiophene (DBT) and 4,6-DMDBT for deep desulfurization with the oxidant of hydrogen peroxide. A T-junction microchannel was applied to form the aqueous slug flow and a long PTFE (polytetrafluoroethylene) capillary with an inner diameter of 1 mm was connected directly downstream to maintain the two-phase dispersion condition. Surfactant of octadecyltrimethyl ammonium bromide (STAB) and phosphotungstic acid (TPA) were mixed in the microchannel to form the combined amphiphilic catalyst directly. The parameters affecting slug formation and DBT oxidation were investigated, including two-phase flow rates, temperature, surfactant type, and catalyst concentrations. DBT conversion of 97% was achieved with a residence time of 1.3 min at 60 degrees C. Furthermore, 4,6-DMDBT could also be effectively oxidized, and increasing the reaction temperature from 25 to 70 degrees C led to a substantial increase in 4,6-DMDBT conversions, from 57% at 25 degrees C to 97% at 70 degrees C. This T-junction microchannel reactor is far superior to the conventional equipment in terms of providing more interfacial area with much less power input.