Large hydrocarbons, pyrolysis aromatics

These different mechanisms and prodnct distribntions, to some extent, are related to the bond dissociation energies, the chain defects of the polymers, and the degree of aromaticity, as well as the presence of halogen and other heteroatoms in the polymer chains. Large amount of styrene monomers can be obtained by pyrolysis of PS, while a wide range of hydrocarbons are prodnced by random degradation of PE and PP [3, 59, 60]. 

In terms of carbon-residue formation (Table II), heat-resistant polymers containing aromatic and heterocyclic units such as polyquinolines and po-lyquinoxalines have a strong tendency to form large condensed systems during pyrolysis and will finally carbonize (36). Formulas that include the occurrence of smaller polynuclear aromatic hydrocarbon systems in asphaltenes are consistent with such behavior when the majority of the nitrogen, oxygen, and sulfur species accumulate in the nonvolatile residue. 

Despite the risks involved, QAPCO took the view that this was an opportunity to recoup more effluent hydrocarbon, which contains propane and butane, and pyrolysis gasoline which contains a large portion of benzene, toluene and xylene aromatics, of use to industrial consumers. 

Crude heavy oils are composed by a large variety of compounds, mostly aromatics and alkylated aromatics with a carbon number from 14 to 25. These heavy aromatic hydrocarbons are very difficult to characterize, the heavier fractions like asphaltenes being impossible to characterize in any way. Because of these complexities, it is very difficult and inaccurate to select one or several pseudo-components to represent the original heavy oil for the purpose of kinetic modelling. A combination of theoretical and experimental methods must be considered to develop a suitable kinetic scheme for heavy oil pyrolysis. The approach followed by Tan et al. 

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