a b s t r a c tOxygenated compounds have gained interest in the last few years because they represent an attractive alternative as additive to diesel fuel for reducing soot emissions. Although dimethyl carbonate (DMC) seems to be a good option, studies about its propensity to form soot, as well as the knowledge of the characteristics of this soot are still missing. For that reason, this paper focuses on the potential of DMC to form soot, as well as on the reactivity and characterization of this soot. Results from pyrolysis experiments performed in an atmospheric pressure flow reactor at different temperatures (1075-1475 K) and inlet DMC concentrations (approximately 33,333 and 50,000 ppm) show that both soot and gas yields are affected by the pyrolysis temperature, while an increase in the inlet DMC concentration only affects slightly the soot yield, without notable influence on the gas yield. DMC shows a very low tendency to produce soot because the CO/CO 2 formation is favoured and thus few carbon atoms are available for soot formation. A chemical kinetic model developed, without incorporating soot particles dynamics, can predict well the gas-phase trends. The comparison of the soot amount profile obtained with the PAH amount profile determined by the model suggests a good first approach toward a model including soot formation. The soot reactivity study toward O 2 (500 ppm) and NO (2000 ppm) at 1475 K, as well as its characterization, show that the higher the temperature and the inlet DMC concentration of soot formation, the lower the reactivity of the soot.

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a b s t r a c tIgnition delay times of dimethyl carbonate DMC were measured using low-and high-pressure shock tubes and in a rapid compression machine (RCM). In this way, the effect of fuel concentration (0.75% and 1.75%), pressure (2.0, 20, and 40 atm) and equivalence ratio (0.5, 1.0, 2.0) on ignition delay times was studied experimentally and by model ing. Experiments cover the temperature range of (795-1585 K). Several models from literature were used to perform simulations, thus their performances to predict the present experimental data was examined. Furthermore, the effect of the thermodynamic data of the CH 3 O(C = O) Ȯ radical species and the fuel consumption reaction CH 3 O(C = O)OCH 3 CH 3 O(C = O) Ȯ + CH 3 , on the simulations of the ignition delay times of DMC was analyzed using the different models. Reaction path and sensitivity analyses were carried out with the final model to present an in-depth analysis of the oxidation of DMC under the different conditions studied. The final model used AramcoMech 2.0 as the base mechanism and included a DMC sub-mechanism available in literature to which the reaction CH 3 O(C = O)OCH 3 CH 3 O(C = O) Ȯ + CH 3 was modified. Good agreement is observed between calculated and experimental data. The model was also validated using available experimental data from flow reactors and opposed flow diffusion and laminar premixed flames studies showing an overall good performance. To this end, studies addressing the thermal decomposition [4-6] , 17 photolysis [7] and oxidation of DMC have been reported in the lit-18 erature. 19 Sinha and Thomson [8] measured species concentrations across 20 DMC/air and propane/DMC/air opposed flow diffusion flames.

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The many simultaneous processes occurring within in a diesel engine make difficult a thorough understanding of the mechanisms responsible for reduction of soot and/or NO X when an oxygenated compound is added to diesel fuel. Thus, in order to explore the use of oxygenated compounds as biofuels/additives, it is interesting to study their conversion under well-controlled laboratory conditions, together with kinetic studies that help to interpret and understand the reaction schemes that occur during such processes. The aim of this work has been to contribute to the knowledge of the dimethoxymethane (DMM) pyrolysis, one of the oxygenated compounds proposed in literature as alternative fuel. In this way, the influence of pyrolysis temperature (1075-1475 K) and inlet fuel concentration (33,333 and 50,000 ppm DMM) on the sooting propensity of DMM, soot reactivity and its properties is analyzed. Therefore, this work includes pyrolysis experiments under different experimental conditions, focusing on the gas-phase analysis and the soot formation, together with a gas-phase model. Additionally, the interaction of soot with O 2 and with NO has been studied, and since soot properties are important on the oxidation rate, selected soot samples have been characterized by different instrumental techniques (elemental analysis, physical adsorption with N 2 , Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), and Raman spectroscopy).