Modelling the plasma chemistry of HCN formation by CH4/NH3 plasma

In this thesis, the ammonia reforming of methane to produce hydrogen cyanide (HCN) was studied using a 0D plasma kinetic model, which performed time-resolved calculations of species densities and incorporates reaction rate coefficients dependent on gas temperature and pressure. A good agreement was observed with the experimental measurements of the selectivity of both the main products, HCN and C₂NH₃.Additionally, a good conversion of NH₃ was validated. However, the model overestimated the conversion of CH₄ compared to the experimental results. Analysis of the reaction pathways from the simulation results reveals that the mechanisms responsible for the formation of different products involve CH3, N, NH2, N₂H₃, H radicals with CNH2, C2NH2, C2NH4, CN2H3 radicals. Modelling the plasma-chemical process described in this paper can be the starting point for understanding the complexity of the chemistry involving CH4 and NH3, as well as for obtaining practical information to understand and predict the plasma dynamics. Certainly, a big step towards improving this model would be the possibility of obtaining rate coefficient data currently unavailable in the literature. In the future, it would also be interesting to investigate the effect of other parameters not expressed in the experimental reference case, such as plasma volume, discharge frequency or with a different type of plasma, in order to hopefully find a value for CH₄ conversion that is more consistent with the experimental one and probably to improve the efficiency of technological applications based on this type of process.