A SOLVENT RESID PHASE-DIAGRAM FOR TRACKING RESID CONVERSION

A plot of molecular weight versus hydrogen content is capable of representing solvent-separated pseudocomponents of petroleum resids and their thermal conversion products by unique areas that are independent of the resid. This solvent-resid phase diagram enables one to track the path of chemical changes that do not convert a molecule completely from one solubility class to others. In this study petroleum resids and the thermal conversion products of the resids and of resid fractions were separated by solubility and clay adsorption into five pseudocomponents: saturates, aromatics, resins, asphaltenes, and coke. The combination of this solvent fractionation and the solvent-resid phase diagram shows how the solubility classes of decreasing solubility evolve during thermal conversion either by increasing aromaticity or by molecular weight growth of low-volatility fragments.