Direct partial oxidation of ethane to ethylene oxide by plasma-catalysis: effects of ethane separate feed and Ag catalysts with Cu and Ni promoters

This study investigated the process of partially oxidizing ethane (C₂H₆) in parallel-plate dielectric barrier discharge (DBD) to generate ethylene oxide (EO) in one step. The effects of the C₂H₆ feed position, overall feed flow rate, and Ag catalysts with Ni and Cu on the performance and stability of EO production were investigated in DBD operating at ambient temperature and atmospheric pressure. A separate stream of C₂H₆ was fed into DBD at the optimum feed position (0.5), with the optimum overall feed flow rate (75 cm³/min), increasing EO selectivity and yield. The increased C₂H₆ feed position and overall feed flow rate decreased the C₂H₆ molecule residence time for electron activation and undesired reactions, decreasing the byproduct selectivities. The 0.1 wt% Ag catalyst with Ni and Cu had less sintering of the Ag particles, better dispersion of the Ag particles, and more specific surface area, significantly increasing the conversions of C₂H₆ and O₂, selectivity and yield of EO, and stability of the catalysts. This is the first time that a catalyst containing 0.1 wt% Cu and 0.1 wt% Ag has been found to have superior performance and stability in EO production from C₂H₆ due to their high electrical conductivity and ability of Cu to prevent coke formation, suppress metal agglomeration, and increase metal dispersion over time.