Effects of the mixing ratios of n-decane/methylcyclohexane binary fuel on the thermal cracking and carbon deposition propensity

Abstract

The development of high-performance fuels for high-speed vehicles requires attention to the effects of interactions between different components of the fuels as coolant on cracking and carbon deposition. Pyrolysis and coking of n-decane and methylcyclohexane (MCH), which represent the n-alkane and cycloalkane classes, respectively, were conducted with electrical heating under supercritical conditions. The gas and liquid products were analyzed by GC–MS, while the coking properties were obtained by characterization methods including programmed temperature oxidation (TPO), scanning electron microscopy (SEM), and Raman spectroscopy. The results demonstrate that at the mixing ratio of 8:2, the gas yield is highest reaching about 41.8 % at 700 °C, while a smaller amount of coking precursors are produced, exhibiting excellent anti-coking performance. Meanwhile, the coke is gradually transformed from filamentous carbon to spherical carbon with a lower graphitization degree and higher oxidation activity. The addition of MCH mainly promotes the generation of ethylene to improve the degree of cracking of the fuel while reducing the generation of propylene and 1,3-butadiene, thereby reducing coke deposition. The regulation of fuel composition can achieve the effect of increasing the cracking depth and inhibiting coking simultaneously. The results can provide theoretical guidance for the adjustment of advanced fuel composition.