OXYGEN PATHWAYS AND CARBON-DIOXIDE UTILIZATION IN METHANE PARTIAL OXIDATION IN AMBIENT-TEMPERATURE ELECTRIC-DISCHARGES

This methane conversion work studies a plasma reaction system for the production of organic oxygenates. The reactor consists of a glass diel ectric interposed between the metal electrodes and a flowing gas strea m through which kilovolt ac power with frequencies in the range of 100 -200 Hz is applied. The geometry for this amounts to an annular system in which gas flows axially between the electrodes, with one electrode covered by a glass plate. The effect of the glass dielectric is to di stribute the microdischarges across the entire electrode area and limi t the duration of each microdischarge. The partial oxidation studies i n this configuration produce methanol and other oxygenates (formaldehy de, formic acid, methyl formate). Selectivities for these products com bined amount to 50-65%. These are the primary products when oxygen is included in the feed to the reactor. Thus far, experiments with low me thane conversions have been conducted (up to around 25%) to minimize l iquid condensation in the reactor. Byproducts here include significant levels of CO and CO2, but it has been determined that CO2 in the feed inhibits further production of CO2 thereby eliminating net CO2 produc tion while increasing CO selectivity. These results show that oxygen a ppears to be needed in order to obtain higher methane conversions and significant oxygenated liquid organic products. CO or CO2 does not app ear to be a substitute for oxygen when trying to generate these desire d oxygenated products.