Production of organic oxygenates in the partial oxidation of methane in a silent electric discharge reactor

This study on the partial oxidation of methane in a silent electric discharge uses an annular reactor consisting of two metal electrodes separated by a gas gap and a glass dielectric covering the outer surface of the inner electrode. The reactor operates at 7000 V and 26-178 W of AC power. The frequency ranges from 100 to 200 Hz. The organic liquid oxygenates formed from the partial oxidation of methane are principally methanol, formaldehyde, methyl formate, and formic acid. This study showed that, when the oxygen partial pressure became limited in the reaction zone, the energy efficiency of the system significantly decreased. It was also shown that, with a recycle, as opposed to without, the selectivity for organic liquids was enhanced by 12%, whereas the COx selectivity decreased by 19% because the recycle had a short per-pass residence time with removal of organic liquid oxygenate products via a condenser. Finally, experimental simulations of reactors in series with intermediate oxygen additions obtained an overall methane conversion of 59%, with 35% yield in organic liquid oxygenates.