Titre du document / Document title
Molecular origins of heavy crude oil interfacial activity. Part 2: Fundamental interfacial properties of model naphthenic acids and naphthenic acids separated from heavy crude oils
Auteur(s) / Author(s)
VARADARAJ Ramesh (1) ;
BRONS Cornelius (1) ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) ExxonMobil Research & Engineering Company, Corporate Strategic Research, 1545 Route 22 East, Annandale, New Jersey 08801, ETATS-UNIS
Résumé / Abstract
Fundamental interfacial properties were determined at the hydrocarbon-water interface for 5β-cholanic acid, abietic acid, and three crude oil naphthenic acids separated from three naphthenic-acid-containing crude oils. Observed interfacial properties were correlated to the composition and chemical structure of crude oil naphthenic acids. Crude oil naphthenic acids are a mixture of primary, secondary, and tertiary, largely cycloparrafinic, organic acids in the molecular weight range of 250-750 amu. The percentage of primary naphthenic acids and proportion of low molecular weight naphthenic acids influence interfacial activity and emulsion stability of water-in-oil emulsions. Naphthenic acid composition and chemical structure determine the nature of molecular aggregation at the hydrocarbon-water interface and impact interfacial properties and emulsion stabilization performance. Crude oil naphthenic acids containing about 80% primary acids and a higher proportion of 250-425 molecular weight species were the most effective in reducing the interfacial tension and stabilizing water-in-oil emulsions. Medium effects on interfacial properties were investigated using a model hydrocarbon, 5:1: hexadecane:toluene, and naphthenic-acid-free crude oil as the hydrocarbon phase. Crude oil naphthenic acids reduce the interfacial tension of the naphthenic-acid-free crude oil to 18.5 dyn/cm, whereas they reduce the interfacial tension of the model oil to 28 dyn/cm. The enhanced activity of the naphthenic acids in the crude oil medium is attributed to the interaction between crude oil naphthenic acids and crude oil asphaltenes.
Revue / Journal Title
Energy & fuels
ISSN
0887-0624
CODEN ENFUEM
Source / Source
2007, vol. 21, n
o1, pp. 199-204 [6 page(s) (article)] (14 ref.)
Langue / Language
Anglais
Editeur / Publisher
American Chemical Society, Washington, DC, ETATS-UNIS
(1987)
(Revue)
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Localisation / Location
INIST-CNRS, Cote INIST : 21106, 35400014331582.0260
Nº notice refdoc (ud4) : 18562696
