Effects of reaction time and temperature on carbonization in asphaltene pyrolysis

The coke formation in bitumen-derived asphaltene pyrolysis was investigated with a molten bath reactor at 430–550 °C. Coke yield increased with reaction time to approach an ultimate level which was reduced from 47 to 41 wt.% with increasing reaction temperature from 430 to 550 °C. H/C ratio of coke decreased with increasing reaction time and temperature. The yields and H/C ratios of gas and liquid products changed accordingly. The experimental observation suggests a complex mechanism of carbonization, involving various reactions such as the dealkylation of side aliphatic chains on rings, the combination of rings radicals by polymerization, cyclization of alkyl chains, dehydrogenation and aromatization of naphthenic rings, condensation and pericondensation of aromatic rings. Various reactions play different roles in different steps of carbonization processes.