M. Yasar et al., Asphaltene and resid pyrolysis. 2. The effect of reaction environment on pathways and selectivities, ENERG FUEL, 15(3), 2001, pp. 504-509
Pyrolysis experiments with resids and isolated asphaltenes from Arabian Lig
ht and Arabian Heavy feedstocks were compared with previous experiments wit
h Hondo and Maya feeds to determine the effect of reaction environment on r
eaction paths, kinetics, and mechanisms. The experiments were at temperatur
es of 400, 425, and 450 degreesC for holding times ranging from 20 to 180 m
in in microbatch reactors. Reaction products were recovered as gas, maltene
, asphaltene, and coke lumps. The maltene, asphaltene, and coke product fra
ctions were collected by a solvent extraction sequence where heptane-solubl
e material was defined as maltene, toluene-soluble material as asphaltene,
and toluene-insoluble material as coke. Gas chromatography revealed the pre
sence of C-1-C-5 paraffins, C-2-C-5 olefins, isoparaffins, H2S, and CO2. Re
sults were summarized by a lumped reaction network that allowed for quantit
ative kinetics analysis. Comparison of relative kinetics and apparent activ
ation energies yielded insight into thermal reaction pathways, feedstock ef
fects, and-asphaltene environment effects. At 400 and 425 degreesC, isolate
d asphaltene reacted selectively to maltene. At 450 degreesC, asphaltene re
acted predominately to coke. Isolated maltene pyrolysis indicated that asph
altene and coke formed in series, i.e., maltene --> asphaltene --> coke.