An experimental and kinetic modeling study of NH3 oxidation in a Jet Stirred Reactor

The increasing interest towards renewable, and more sustainable energy sources imposes a widerange analysis of the underlying chemistry, in order to maximize the efficiency of combustion devices and reduce pollutant emissions. In this context, ammonia chemistry has recently gained major attention: it is present in biogas and bio-oil, in trace amounts. Investigating ammonia chemistry can benefit from several studies carried out in the past decades on its pyrolysis and oxidation behavior. However, scarce literature is available on the conditions of interest previously mentioned, since the presence of ammonia in trace amounts results in superoxidative conditions. The available kinetic models of ammonia have been built up by mostly relying on hightemperature data, obtained in ideal reactors. On the other side, few work has been carried out to investigate its oxidation at lower temperatures. In order to further investigate this topic, and to provide a stronger support for kinetic model validation, in this study the oxidation of ammonia in diluted conditions, at relatively low temperatures (T < 1200 K) and a pressure close to atmospheric, is investigated by using a Jet Stirred Reactor. In addition to ammonia conversion, the formation of Nitrogen Oxides (NOx) is also analyzed. At the same time, a detailed kinetic mechanism for ammonia oxidation is developed by leveraging the most recently available kinetic data on experimental and theoretical reaction rates, and is used to analyze the obtained data, after being validated against the literature data in similar conditions

Study of oscillations during methane oxidation with species probing

Biogas has been considered as a renewable energy source with respect to fossil fuels due to its sustainability, security supply, and environmental friendly potential [1-4]. Methane occupies a large part in biogas. It is of great value to review the methane oxidation for a primary understanding of the features associated with biogas combustion. It was found that dynamic behavior in terms of methane oxidation occurred under specific conditions. The first methane oxidation oscillation experiments were conducted by [5] in a jet-stirred reactor (JSR) and were extended to a higher inlet temperature [6]. The map of dynamic behavior was drawn in terms of various C/O ratios and temperatures ranging from 1025-1275 K at a fixed 90% nitrogen bath gas. Recently, Lubrano Lavadera et al. [7] investigated the main parameters, such as, equivalence ratios (0.5-1.5), residence time (1.5-2 s), various bath gases (N2, CO2, He, H2O), on the oscillatory behavior of methane oxidation. However, to our best knowledge, studies of dynamic phenomenology with species probing have never been reported. Because of the heat release in terms of the exothermic or endothermic reactions, the temperature and species oscillations are strongly coupled during fuel oxidation. In order to put emphasis on species dynamic behavior, very diluted conditions are needed to decouple as much as possible temperature and species oscillations. The purpose of this work is to investigate the effects of various parameters: inlet mole fraction of methane (0.1-0.5%), stoichiometric condition (=1) and reactor temperatures (950-1200 K), on the species oscillations during methane oxidation. A detailed kinetic mechanism (POLIMI) [8] is selected to interpret the experimental data

Experimental and modelling study of the oxidation of methane doped with ammonia

The oxidation of methane doped with ammonia was experimentally and theoretically studied in order to better understand the interactions between these two molecules in combustion processes fed with biogas. Experiments were carried out in a jet-stirred reactor. Several diagnostics were used to quantify reaction products: gas chromatograph for carbon containing species, a NOx analyzer for NO and NO2, and continuous-wave cavity ring-down spectroscopy for ammonia. Experimental data were satisfactorily compared with data computed using a model developed by Politecnico di Milano

Experimental and Modeling Study of the Oxidation of Benzaldehyde

The gas-phase oxidation of benzaldehyde has been investigated in a jet-stirred reactor. Benzaldehyde is an aromatic aldehyde commonly considered in bio-oils surrogates or in the oxidation of fuels such as toluene. However, its oxidation has never been previously investigated experimentally and no product formation profiles were reported in the few pyrolysis studies. In this study 48 species, mainly CO, CO2 and phenol were detected using gas chromatography, which indicate a rapid formation of phenyl radicals. This was confirmed by a kinetic analysis performed using the current version of the CRECK kinetic model, in which reactions have been updated