Pyrolysis of Ethanol: Gas and Soot Products Formed

Ethanol may be used in diesel-ethanol mixtures in order to decrease soot emissions. Therefore, it is important to evaluate the contribution of ethanol to soot formation. The influence of the temperature on the pyrolysis of ethanol under sooting conditions has been studied. Pyrolysis experiments were carried out in a quartz, reactor in the 700-1200 degrees C temperature range, for an inlet C2H5OH concentration of 50 000 ppm and a gas residence time in seconds of 1706/(T/K). The concentrations of the gases analyzed in the experiments are shown in this work together with simulations carried out with a literature kinetic model. Theoretical and experimental results present, generally, a good agreement in spite of the model not taking into account the soot formation. Under the studied conditions, soot formation has been observed above 1050 degrees C. With the soot samples obtained, a study of their reactivity toward O-2 and NO has been carried out, and several characterization techniques, such as elemental analysis, Brunauer-Emmett-Teller (BET) surface area, transmission electron microscopy, and X-ray diffraction have been used to study the structural properties of the collected soot samples and relate them to their reactivity. It has been observed that the soot samples formed at higher temperatures exhibit a lower reactivity toward O-2 and NO, and the characterization analyses support these results.