Abstract:
Ethylene oxide (C2H4O, EO) is the valuable chemical feedstock or intermediate for many important applications, such as solvents, antifreeze, textiles, detergents, adhesives, polyurethane foam, and pharmaceuticals. Ethylene oxide is a colorless flammable gas or refrigerated liquid with a faintly sweet odor and is the simplest molecule of an epoxide. The partial oxidation of ethylene to ethylene oxide, so-called ethylene epoxidation, has been of great interest in many global research works. The objective in this work was to investigate the ethylene epoxidation performance using a parallel plate dielectric barrier discharge (DBD) system by initially producing oxygen active species prior to reacting with ethylene. The effects of various operating parameters, including ethylene feed position, oxygen-to-ethylene feed molar ratio, Ag/SiO2 catalyst existence, applied voltage, input frequency, and feed flow rate on the ethylene epoxidation activity were examined. It was found that the highest EO selectivity of 72 % was obtained when the DBD was operated at an ethylene feed position fraction of 0.5, an O2/C2H4 feed molar ratio of 0.2:1, the presence of Ag loading of 10 %, an applied voltage of 19 kV, an input frequency of 500 Hz, and a total feed flow rate of 50 cm3/min. At these optimum conditions, the power consumption to create an EO molecule was found to be as low as 16.56×10-16 Ws /molecule of E0 produced. Moreover, the presence of Ag catalyst loaded on SiO2 provided a much higher EO selectivity (%) as twice as compared with the sole plasma system.
