Chemical Kinetics of Asphaltene Pyrolysis

This work presents a predictive and generally applicable approach to asphaltene pyrolysis modeling. Asphaltenes derived from heavy fuel oil 380 (HFO) were characterized using elemental analysis and FT-ICR MS. The structural information derived from the chemical analysis guided the formulation of five surrogate molecules. The atomic ratios of the surrogate molecules were defined to replicate the elemental composition of each data as their linear combination. This approach makes the model flexible and readily applicable to any asphaltene fraction by only knowing its elemental composition. The formulation of the kinetic model proceeded through chemistry-related considerations on the reactions most likely to take place at a given temperature for each component. The authors also used the experimental data obtained from thermogravimetric analysis (TGA) in an inert atmosphere, either reported in the literature or generated by the authors for the development of the kinetic scheme. The kinetic scheme consists of five first-order reactions. The activation energy (Ea) and Arrhenius (A) coefficient were tuned using a subset of the experimental data available and validated with the remaining data. The product distribution of the in-house-produced samples was obtained from a TGA–MS and TGA–FTIR analysis and used to adjust the stoichiometric coefficients together with experimental data reported in the literature. The model presented a satisfactory agreement with the most recent experimental data while showing some discrepancies with older data, which are discussed in the paper. The model reported in this work represents the first step of a more comprehensive project aimed to reconstruct the chemical kinetics of HFOs as a combination of their saturate, aromatic, resin, and asphaltene fractions.