Research on the pyrolysis characteristics and kinetics of two typical inferior heavy oils

Abstract

• Isoconversional methods and DAEM were used to calculate kinetic parameters. • Major weight loss of heavy oil pyrolysis occurred in active pyrolytic stage. • DAEM method had a high applicability to the pyrolysis of heavy oil. The present study deals with the pyrolysis characteristics of two typical inferior heavy oils slurry oil (SO) and deoiled asphalt (DOA) based on thermogravimetric data at multiple heating rates of 5, 10, 15 and 20 °C/min. Three isoconversional methods (Friedman, FWO and KAS) and distributed activation energy model (DAEM) method were used to evaluate the kinetics. The results showed that major mass loss of SO and DOA occurred in active pyrolytic stage, at which the mass loss rate reached up to 90.9 wt% (SO) and 55.5 wt% (DOA), respectively. The emissions of CH 4 , H 2 O, CO and CO 2 in the temperature range 400–600 °C contributed to the mass loss of DOA, whereas the mass loss of SO was ascribed to the cracking and condensation. The average activation energy ( E ) of SO and DOA were 101.48 and 219.32 kJ/mol for Friedman, 89.51 and 191.90 kJ/mol for FWO, 82.05 and 190.07 kJ/mol for KAS, respectively. DAEM method had a high applicability to the pyrolysis process of SO and DOA. The calculated peak proportions of four independent hypothetical components basically conformed to the fraction proportions of SO and DOA. The weighted E of DAEM method was higher than the average E of three isoconversional methods, explaining the four components of heavy oil was not single chemical reactions during pyrolysis, but interactive reaction.