On the relation between solubility, chemical structure and pyrolysis of complex hydrocarbon mixtures: Experimental campaign and model

The increasing interest in upgrading residual fuels is driving fundamental research toward a deeper understanding of their properties. Residual fuels, heavy and viscous oils left after crude oil refining, are highly complex mixtures of thousands of different molecules spread over a wide boiling range. Several research efforts have attempted to characterize residual oils over the last century, resulting in the SARA (saturates, aromatics, resins, asphaltenes) analysis being the most widely adopted characterization method. This work showed that a linear combination of the SARA fractions can mimic the actual oil with good accuracy, both in terms of chemical composition and pyrolytic behavior. This is referred to as the additive property in the manuscript. In this work, the additive property was experimentally verified using different experimental techniques (CHNS-O, FT-ICR- MS, and TGA). The validity of such property suggests that neglecting interactions among the different fractions during their pyrolysis is a good approximation, thus enabling the description of the raw fuel on the basis of its main components. This result seems implicitly to confirm that also in the liquid phase large hydrocarbons pyrolyze without strong interactions with the surrounding environments, similarly to what happens in the gas phase. This finding also results in an advantage for model developments, where the pyrolysis of different fuels can be described as a linear combination of SARA-independent models.