Asphaltene reaction pathways-v. Chemical and mathematical modeling

The pyrolysis of a generic, fully hydrocarbon asphaltene was simulated by combining model-compound-deduced thermolysis kinetics and pathways with asphaltene structural information. The latter was used in a Monte Carlo simulation of 10,000 prototype unit sheets, whose ensemble average conformed with the distribution and averages of structural probability density functions. Asphaltene reactions were thus mathematically equivalent to changes in the distributions and average of asphaltene structural information. The model-coumpound-based reaction pathways and kinetics of the unit sheet provided the temporal variations of the structural information, and the mathematical model was thus truly a priori with respect to asphaltene prolysis kinetics. Reaction products were assembled using the same Monte Carlo method as for the reactant but with reaction-altered distribution functions. Average structural parameters predicted by the model for the reactant asphaltene were consistent with literature values, and the temporal variation of the yields of solubility-based products fraction from simulated pyrolyses were in good accord with experimental result. These observations demonstrate that reaction engineering data derived from model compounds can be used to provide reasonable estimates of the reactivity of complex substrates such as petroleum asphaltenes.