Cold Plasma Partial Oxidation of Methane to Higher Value Products

The market for syngas, an important intermediate for the synthesis of methanol, hydrogen, ammonia, and synthetic petroleum fuels, is expected to grow globally at a compound annual growth rate of more than 14% by 2020. The most widely used process for making syngas is steam reforming of methane; however, the process is energy intensive and is more expensive than the DOE’s cost targets for the production of hydrogen. Syngas production through partial oxidation of methane is not as common as steam reforming but does have reduced energy costs. Short contact time partial oxidation of methane has been shown to have promise on the bench scale; however, achieving partial oxidation in practice is difficult due to the tendency to completely oxidize methane to CO2 and water. Reactive Innovations proposes to use the technology developed in Phase I to limit the oxygen delivery to a short contact time reactor for the selective production of syngas. During this Phase I program, a permeable, conductive oxygen conduit was developed for the plasma activated partial oxidation of methane. Use of these conductive conduits limited the oxygen delivery to the plasma zone and enabled the conversion of methane with high selectivity into desired products of hydrogen and hydrocarbons while limiting the over-oxidation to CO2 and water. Adding catalyst to the system increased product selectivity. Similar results for controlled partial oxidation of methane were seen when applying the oxygen conduit to the thermally activated process. The main focus of the Phase II program is to optimize the oxygen conduit and apply it to a high temperature process for the conversion of methane into syngas. This program will optimize the conversion efficiency, optimize the single channel oxygen conduit design, and develop/evaluate a multi-channel reactor system. A sub-task will be aimed at examining the use of the optimized oxygen conduits in a plasma-based process so that results can be compared to the thermal process. The benefits of the technology will be a more efficient method to react natural gas into valuable products such as syngas and other value added products. The use of a controlled oxygen delivery system also mitigates the need for a large O2/CH4 co-feed which becomes an explosion hazard when used on an industrial scale. In addition, the O2 delivery system allows for catalyst regeneration in-situ if necessary as it can deliver oxygen right to a deactivated catalyst surface.