Overcoming Thermal Degradation during Continuous Conversion of Water into Hydrogen Peroxide in a Flexible Plasma Reactor

By control of the nanosecond pulsation, energy input, and flow, it is possible to achieve commercial-level hydrogen peroxide (H$_2$O$_2$) concentrations using only water and plasma in a continuous process while minimizing thermal degradation. Time-resolved ultrafast Optical Emission Spectroscopy was employed to observe the formation of reactive species, shedding light on the underlying mechanisms. This study also found that thermal degradation has a critical role, which was effectively managed through quenching of the plasma zone. A parametric scan of pulse duration and pulse repetition frequency of the microwave power showed a significant influence on H$_2$O$_2$ formation, whereby the mean power also plays an important role. Additionally, the H$_2$O$_2$ concentration was found to be inversely proportional to the water flow rate. A maximum concentration of 0.17 wt % was achieved with 1.2 g/kWh based on the absorbed power at a flow rate of 0.2 mL/min. This plasma reactor technology shows promise for further development as a decentralized solution for the green chemical synthesis of H$_2$O$_2$.