The conversion of atmospheric nitrogen into valuable compounds, that is, so-called nitrogen fixation, is gaining increased interest, owing to the essential role in the nitrogen cycle of the biosphere. Plasma technology, and more specifically gliding arc plasma, has great potential in this area, but little is known about the underlying mechanisms. Therefore, we developed a detailed chemical kinetics model for a pulsed-power gliding-arc reactor operating at atmospheric pressure for nitrogen oxide synthesis. Experiments are performed to validate the model and reasonable agreement is reached between the calculated and measured NO and NO yields and the corresponding energy efficiency for NO formation for different N /O ratios, indicating that the model can provide a realistic picture of the plasma chemistry. Therefore, we can use the model to investigate the reaction pathways for the formation and loss of NO . The results indicate that vibrational excitation of N in the gliding arc contributes significantly to activating the N molecules, and leads to an energy efficient way of NO production, compared to the thermal process. Based on the underlying chemistry, the model allows us to propose solutions on how to further improve the NO formation by gliding arc technology. Although the energy efficiency of the gliding-arc-based nitrogen fixation process at the present stage is not comparable to the world-scale Haber-Bosch process, we believe our study helps us to come up with more realistic scenarios of entering a cutting-edge innovation in new business cases for the decentralised production of fertilisers for agriculture, in which low-temperature plasma technology might play an important role.

Low-temperature plasmas are gaining a lot of interest for environmental and energy applications. A large research field in these applications is the conversion of CO into chemicals and fuels. Since CO is a very stable molecule, a key performance indicator for the research on plasma-based CO conversion is the energy efficiency. Until now, the energy efficiency in atmospheric plasma reactors is quite low, and therefore we employ here a novel type of plasma reactor, the gliding arc plasmatron (GAP). This paper provides a detailed experimental and computational study of the CO conversion, as well as the energy cost and efficiency in a GAP. A comparison with thermal conversion, other plasma types and other novel CO conversion technologies is made to find out whether this novel plasma reactor can provide a significant contribution to the much-needed efficient conversion of CO . From these comparisons it becomes evident that our results are less than a factor of two away from being cost competitive and already outperform several other new technologies. Furthermore, we indicate how the performance of the GAP can still be improved by further exploiting its non-equilibrium character. Hence, it is clear that the GAP is very promising for CO conversion.

For the first time an extensive experimental and computational study was performed on the effect of N2on CO2splitting in a dielectric barrier discharge plasma.

A chemical kinetics model is developed for a CO 2 /N 2 microwave plasma, focusing especially on the vibrational levels of both CO 2 and N 2 . The model is used to calculate the CO 2 and N 2 conversion, as well as the energy efficiency of CO 2 conversion, for different power densities and for N 2 fractions in the CO 2 /N 2 gas mixture ranging from 0 till 90%. The calculation results are compared with measurements, and agreements within 23% and 33% are generally found for the CO 2 conversion and N 2 conversion, respectively. To explain the observed trends, the destruction and formation processes of both CO 2 and N 2 are analyzed, as well as the vibrational distribution functions of both CO 2 and N 2 . The results indicate that N 2 contributes in populating the lower asymmetric levels of CO 2 , leading to a higher absolute CO 2 conversion upon increasing N 2 fraction. However, the effective CO 2 conversion drops, because there is less CO 2 initially present in the gas mixture, and thus also the energy efficiency drops with rising N 2 fraction.