Direct synthesis of liquid oxygenates in a nonequilibrium plasma microreactor

A flow-type nonequilibrium plasma microreactor has been developed for direct synthesis of liquid oxygenates from partial oxidation of methane near 0 °C at atmospheric pressure. Plasma microreactor provides extreme quenching environment with condition created to stimulate the condensation of oxygenates on the walls and later removed by water injection to prevent full oxidation. The removal of incomplete oxidation products prevents further oxidation with excited species in the discharge region. One-pass 15 % liquid oxygenate yield has been obtained with main components of methanol, formaldehyde and formic acid. Hydrogen peroxide has been found as key component which oxidizes post-discharge product as well as increasing liquid oxygenate yield if injected into discharge. Reaction mechanism, role of water and hydrogen peroxide injections have been largely clarified from experiments with D₂O and D₂O₂ isotopes.