Combining CO2 conversion and N2 fixation in a gliding arc plasmatron

Industry needs a flexible and efficient technology to convert CO2 into useful products, which fits in the Carbon Capture and Utilization (CCU) philosophy. Plasma technology is intensively being investigated for this purpose. A promising candidate is the gliding arc plasmatron (GAP). Waste streams of CO2 are often not pure and contain N-2 as important impurity. Therefore, in this paper we provide a detailed experimental and computational study of the combined CO2 and N-2 conversion in a GAP. Is it possible to take advantage of the presence of N-2 in the mixture and to combine CO2 conversion with N-2 fixation? Our experiments and simulations reveal that N-2 actively contributes to the process of CO2 conversion, through its vibrational levels. In addition, NO and NO2 are formed, with concentrations around 7000 ppm, which is slightly too low for valorization, but by improving the reactor design it must be possible to further increase their concentrations. Other NO-based molecules, in particular the strong greenhouse gas N2O, are not formed in the GAP, which is an important result. We also compare our results with those obtained in other plasma reactors to clarify the differences in underlying plasma processes, and to demonstrate the superiority of the GAP.