High pressure ammonia oxidation in a flow reactor

•Ammonia oxidation at high pressure is studied.•Increasing pressure shifts ammonia conversion to lower temperatures.•Increasing oxygen concentration shifts ammonia conversion to lower temperatures.•Main product of NH3 conversion is N2, with negligible formation of NO, NO2 and N2O.•Experimental results were simulated with a literature compiled kinetic mechanism. The present work deals with an experimental and modeling analysis of ammonia oxidation at high pressure (up to 40 bar), in the 600–1275 K temperature range using a quartz tubular reactor and argon as diluent. The impact of temperature, pressure, oxygen stoichiometry and presence of NO has been analyzed on the concentrations of NH3 and N2 obtained as main products of ammonia oxidation. The main results obtained indicate that increasing either pressure or stoichiometry results in a shift of NH3 conversion to lower temperatures. The effect of pressure is particularly significant in the low range of pressures studied. The main product of ammonia oxidation is N2, while NO, NO2 and N2O concentrations are below the detection limit for all the conditions considered. The experimental results are simulated and interpreted in terms of a literature detailed chemical kinetic mechanism, which, in general, predicts satisfactorily the experimental results.