Ethylene epoxidation in a low-temperature parallel plate dielectric barrier discharge system with two dielectric layers

Abstract

Ethylene oxide, which is an important petrochemical substrate in chemical industry, is used as an intermediate in the manufacture of various useful chemicals such as polyethylene glycol, polyethylene oxide, detergents, and solvents. In commercial processes. ethylene oxide was generated by the ethylene epoxidation reaction under high temperature operation, which results in high energy consumption. The objective of this work was to determine the optimum condition for the maximum ethylene oxide selectivity by using a low-temperature parallel plate dielectric barrier discharge (DBD) system, with two glass plates as dielectric barriers under ambient temperature and pressure to produce active oxygen species prior to reacting with ethylene in order to maximize ethylene oxide production. The effects of applied voltage, input frequency, and O₂/C₂H₄ feed molar ratio, as well as ethylene feed position, on ethylene epoxidation activity were examined. The DBD system with two rough glass plates was found to provide the highest EO selectivity of 68.15 % and the highest EO yield of 10.88%, at 23 kV, 500 Hz, an O₂/C₂H₄ feed molar ratio of 1:5, and an ethylene feed position fraction of 0.5, which gave twice as much as EO selectivity in a DBD system with a single smooth dielectric glass plate.