Propylene Epoxidation in a Low-Temperature Parallel-Plate Dielectric Barrier Discharge Reactor with Two Frosted Glass Plates: Effects of Separate Propylene Feed

The epoxidation reaction of propylene (C₃H₆) for propylene oxide (PO) production was, for the first time of its kind, investigated in a low-temperature parallel-plate dielectric barrier discharge system with two frosted glass plates and a separate C₃H₆ feed under ambient condition. For the mixed feed experiments, the maximum PO selectivity was found at a feed molar air-to-C₃H₆ ratio of 0.5:1, an applied voltage of 7 kV, an input of 550 Hz, and a feed flow rate of the mixed gas of 100 cm³/min (corresponding to a residence time (RT) of 12.1 s). At the optimum operational conditions, a separate C₃H₆ feed position fraction of 1 (complete separation of C₃H₆) with total reactant feed flow rate of 100 cm³/min (corresponding to an O₂ residence time (RT) of 24.1 s), the greatest propylene oxide selectivity of 16.40% was achevied. The relatively high PO selectivity with very low selectivities for all other products and with the absence of both CO and CO₂ obseved in this studied resulted from less active of C₃H₆ due to the separate feed of C₃H₆. The C₃Hseparate feed is fundamentally responsible for the reduction in all the undesired reactions including cracking, dehydrogenation, coupling, and oxidations of C₃H₆.

Graphical Abstract