Effects of endothermic hydrocarbon fuel composition on the pyrolysis and anti-coking performance under supercritical conditions

N-dodecane (C12) and decahydronaphthalene (DHN) were considered as the model compounds of alkanes and cycloalkanes, respectively. Pyrolysis of C12, DHN and C12-DHN binary fuels with different mass ratios of C12/DHN was performed on a supercritical cracking experimental apparatus equipped with a tubular reactor under supercritical conditions (3.5 MPa and 700 °C). The coke amount deposited on the inner surface of the tubular reactor was determined by weight method using an electronic analytical balance with a high measurement precision. Effects of EHF composition on the pyrolysis and anti-coking performance were studied. It was observed that there were reciprocal inhibition and competition effects during the co-pyrolysis of C12 and DHN. The increasing ratio of C12/DHN exerted a positive effect on gas yields of EHFs, but hardly on selectivities of H2 and alkenes (≤C4). Heat sink of EHFs depended largely on the gas yields representing thermal cracking level. C12/DHN ratio greatly affected the coke amount and morphologies of EHFs. Proper ratios of alkanes/cycloalkanes for advanced EHFs should not be less than 3/7 in terms of anti-coking performance. Inherent consistency could be obtained among carbon deposition, coking precursors, elements distribution and morphologies of coke. The results could provide a significant guidance on the design and development of advanced EHFs.