Separation of petroleum vacuum residues and its physico-chemical characterization

摘要

The fractionation by extraction with non polar solvents of similar nature, but of different boiling points, is a separation analogous to fractional distillation which yields basically complex fractions first by boiling ranges and consequently, by molecular weight ranges (1). The amount of fractions separated depends on extent of dilution, temperature, nature of the solvents as well as the equilibrium of the system (2). The separation of residues into two fractions asphaltenes and maltenes is brough about by means of low molecular weight praffinic hydrocarbons, which have been recognized to posses selective solvency for hydrocarbon systems and is known as solvent deasphalting. Ethyl acetate has been used to eliminate both resins and asphaltenes from the oil in one step and thus improving the quality of deasphalted oil (3). Solvent deasphalting effect has been studied on the onset, composition and yield of asphaltenes (4-6), and also on volatiles, aromatics, sulfur and metal as a function of yield (7).