Effects of molecular structures on the pyrolysis and anti-coking performance of alkanes for thermal management

Abstract

Pyrolysis of normal- and iso-alkanes were carried out using a supercritical cracking experimental apparatus equipped with an electrically heated tubular reactor under supercritical conditions (3.5MPa and 700°C). The hydraulic resistance method (HRM) was applied to quantitatively evaluate the carbon deposition. Effects of molecular structures on the pyrolysis and anti-coking performance of alkanes were studied. It was found that the gas yield and heat sink (HS) increased with the increasing carbon chain length of normal alkanes. Normal alkanes with even carbon number (NPEC) exhibited better anti-coking performance than those with adjacent odd carbon number (NPOC). Compared with normal alkanes, iso-alkanes could generate higher gas yields. However, lower HS and yield of hydrogen and alkenes (⩽C4), as well as poorer resistance to carbon deposition were observed for iso-alkanes with more than two methyls. There was an optimum value of the ratio of NPEC/NPOC for the balanced HS and anti-coking performance in the design of high-performance endothermic hydrocarbon fuels (EHFs).