Study on reaction force field simulation of pyrolysis interaction among components of oily sludge

The composition of petroleum hydrocarbons in oily sludge is complex, and it is difficult to reveal the interaction between components in the pyrolysis process only by the macroscopic analysis results of products. Five compounds, namely n-dodecane, 1-dodecene, methylcyclohexane, p-xylene, and 1-methylnaphthalene, were represented as alkanes, alkenes, cyclanes, monocyclic aromatics and polycyclic aromatic hydrocarbons in oily sludge to construct model compounds of petroleum hydrocarbon in oily sludge. The molecular dynamics simulation method based on reaction field was used to study the distribution of products and the interactions among components during pyrolysis. The results showed that the pyrolysis products of model compounds were dominated by small molecular compounds H2 and C1-3, C2H4 and C3H6 in the early pyrolysis phase, and C2H2, C3H4 and H2 in the late pyrolysis phase. Compared with the separate pyrolysis of each component in the model compound, the consumption rate of each component in the mixed pyrolysis process of petroleum hydrocarbon is obviously accelerated, and the number of pyrolysis product fragments also increases to a certain extent. According to the first-order reaction kinetic model, the apparent activation energy of petroleum hydrocarbon components in the mixed pyrolysis process decreased to different degrees, among which the apparent activation energy of alkanes, alkenes, and cycloalkanes decreased by 16.493 kJ/mol, 50.571 kJ/mol and 146.289 kJ/mol, respectively, which proved the synergistic effect of pyrolysis among petroleum hydrocarbon components of oily sludge from the level of molecular simulation. © 2021, Editorial Board of CIESC Journal. All right reserved.