Ignition of non-equilibrium methane dielectric barrier discharges in a multiphase plasma-liquid microfluidic device

Atmospheric pressure plasma conversion of methane is usually addressed in gas-only systems, such as dry reforming of methane. Introducing a liquid in such a system enables direct utilization of plasma-produced radicals, such as methyl (CH₃), as a reactant in the liquid. Methylation of organic liquids by this technique can lead to the sustainable production of high-value products. A dielectric-barrier-discharge (DBD) microfluidic reactor having a 500 μm × 500 μm cross-section was developed to investigate the characteristics of methane-containing atmospheric pressure plasmas in contact with organic solvents. The sensors included optical emission spectroscopy and chip surface temperature measurement to estimate and predict plasma initiation in these methane-containing systems and provide insights into the plasma-liquid interfacial behavior. Fluids having high liquid hold-up, low boiling point, and low dielectric constant have been found to have adverse effects on non-equilibrium DBD methane plasma ignition.