Simultaneous generation of hydrogen and carbon monoxide using a wet-type plasma reactor

Nonthermal plasma enables the conversion of carbon dioxide (CO 2 ) into carbon monoxide (CO), which can be used as a reducing agent or synthesis gas fuel. Additionally, wet-type plasma reactors can produce hydrogen (H 2 ) from liquid water (H 2 O). The objective of this study is to use a wet-type plasma reactor to simultaneously generate H 2 and CO from liquid water and CO 2 . The effects of water flow rate, α-alumina pellets packing, discharge wire diameter, and discharge frequency on product generation are evaluated. The maximum average H 2 and CO concentrations are 632 and 750 ppm, respectively, in the wet-type packed-bed plasma reactor at a water flow rate of 50 mL/min, discharge wire diameter of 2 mm, and pulsed frequency of 420 Hz, whereas the wet-type plasma reactor without pellet packing achieves concentrations of 2221 and 2086 ppm, respectively, at the same water flow rate with a wire diameter of 10 mm and pulsed frequency of 840 Hz. These results suggest that a wet-type plasma reactor without pellet packing is more favorable for the simultaneous production of H 2 and CO, as it promotes efficient electron-induced dissociation of H 2 O and CO 2 while suppressing •OH-related secondary reactions. This reactor demonstrates an H 2 generation performance equivalent to or better than that of conventional humidified gas-phase plasma systems in the simultaneous generation of H 2 and CO. These results indicate that the direct interaction of plasma with liquid water is effective for the simultaneous generation of H 2 and CO from CO 2 and water.