Extremely Low Temperatures for the Synthesis of Ethylene Oxide

The partial oxidation of ethylene in a methane atmosphere by pure oxygen is the most important industrial process for the synthesis of ethylene oxide. However, due to the high reactivity and exothermicity of the reaction system, the overall production is limited by kinetic and safety issues. The shift toward mild operative conditions can support the management of undesirable side reactions, enhancing the performance of the whole process. In the future, the direct use of liquefied ethylene and oxygen-enriched air, a low-cost waste in membrane-based nitrogen production, can provide convenient sources for heat removal as well as promote the use of innovative and more sustainable solutions. This work is focused on the experimental and numerical characterization of the oxidation of ethylene/methane/nitrogen/oxygen mixtures at different operative conditions, including extremely low temperatures, and oxidant compositions. To this aim, the laminar burning velocity and flammability limits were first measured utilizing the heat flux burner and compared with detailed kinetic mechanisms and experiments retrieved from the current literature. The reported data were adopted to identify the operational limits for innovative processes, paving the way to unlocking the potential of innovative chemistry at extreme conditions. Eventually, key performance indicators accounting for kinetic and safety aspects were defined to identify the most sustainable and convenient operative conditions.