SARA Separation and Evaluation of Seven Crude Oils from Argentina

PINZON, J.; CRAVERO, M.; REINOSO, T. ; TERNAVAZIO, R.; RIVALDI, E.; ROMERO, MARCELO; CISMONDI DUARTE, M.

Buenos Aires

Congreso; 11th World Congress of Chemical Engineering; 2023

The compositional analysis of crude oils provides information to understand the behavior of the samples, allowingbetter exploitation, establishing superior processing methods, conducting an adequate choice of catalysts, andavoiding transportation problems, among others. An initial method of separating crude oil is distillation at atmosphericpressure, which allows separating the more volatile fractions of the crude. The chemical complexity of the crude,which impedes a clean distillation,together with the repeated presence of residues during the process, impose clearlimitations to distillation as a unique separation stage.Therefore, it is normally complemented with other types ofseparations, in order to obtain more representative fractions of the crude, with varying volatility and/or polarity.The objective of this work was to analyze seven crude samples (conventional and non-conventional types), fromdifferent production fields in Argentina. This determination begins with crude dehydration (Dean-Stark Method) and isfollowed by the distillation of the crude up to a temperature of 180°C. The crude residue and also the originaldehydrated crude are investigated for asphaltenes precipitation. The method of precipitation of asphaltenes consistsof solubilizing n-alkane and crude oil in a ratio of 40/1 (v/v), the solution is left to stand for 24 h. After the product wascentrifuged, the supernatant fluid is removed and the sediment was washed with alkane three times. The product wasdried at 60 °C overnight and components were characterized by using FTIR. The supernatant liquid was separatedfrom the solid (asphaltene) and then fractionated using a chromatography column, to complete a SARA-typeseparation. The information provided by this technique gives us more information about the identity of the crude.The SARA-type separation used was by column liquid chromatography, with silica gel and alumina as stationaryphases. Several eluents with increasing polarities were added to the column obtaining different fractions. Saturatesare eluted with n-hexane, aromatics with toluene or n-hexane-dichloromethane (75:25, vol:vol), and resins withdichloromethane-methanol (95:05, vol:vol) [1]. Before fractionation, crude oil samples are characterized for somephysical and chemical properties using ASTM standards. Untreated and fractionated samples were characterized byFTIR.As a result, crude samples are thoroughly characterized, allowing better understanding and anticipating thedifferences in the behavior of different conventional and unconventional crudes.