Oxidation of methylamine (CH3NH2)/CH4/NO mixtures in an atmospheric-pressure flow reactor

The oxidation of methylamine (CH₃NH₂) and methane mixtures has been studied by experiments in a flow reactor at atmospheric pressure and temperatures of 350–1450 K. In addition to temperature, stoichiometry (ranging from fuel-rich to fuel-lean conditions) and the presence of NO have been evaluated. Several diagnostic techniques have been used to experimentally quantify many different species: gas chromatography, Fourier Transform Infra-red spectroscopy (FTIR) and an infra-red NO analyzer. Results show a negligible influence of stoichiometry both on the conversion of MEA and CH₄ in the absence of NO, while the presence of NO acts to inhibit the conversion of CH₄ with no appreciable influence on MEA conversion. This indicates the complex interaction occurring in the MEA/CH₄/NO mixtures, for which the mechanism is not able to properly predict the conversion of CH₄ in the presence of NO, while the rest of compounds are well reproduced both in the absence and presence of NO. This fact, together with the probable formation of species containing C and N, due to the presence of additional unidentified species and the deep analysis of the mass balances carried out, supports the idea of the formation of C-N species, not clearly identified so far. The literature mechanism used in simulations has provided good results in reproducing most of the species and conditions considered. The largest discrepancy has been observed for CH₄ conversion in the presence of NO, supporting the existence of missing interactions in the mechanism.