STABILIZATION OF ASPHALTENES IN ALIPHATIC SOLVENTS USING ALKYLBENZENE-DERIVED AMPHIPHILES .1. EFFECT OF THE CHEMICAL-STRUCTURE OF AMPHIPHILES ON ASPHALTENE STABILIZATION

Stabilization of crude oil asphaltenes in apolar alkane solvents was i nvestigated using a series of alkylbenzene-derived amphiphiles as the asphaltene stabilizers. In this paper (i.e., part 1), we present the s tudy on the influences of the chemical structure of these amphiphiles on the effectiveness of asphaltene solubilization and on the strength of asphaltene-amphiphile interaction using both UV/vis and FTIR spectr oscopies. The results showed that the amphiphile's effectiveness of as phaltene stabilization was primarily controlled by the polarity of the amphiphile's head group and the length of the amphiphile's alkyl tail . Increasing the acidity of the amphiphile's head group could promote the amphiphile's ability to stabilize asphaltenes by increasing the ac id-base attraction between asphaltenes and amphiphiles. On the other h and, although decreasing the amphiphile's tail length increased the as phaltene-amphiphile attraction slightly, it still required a minimum t ail length (six carbons for p-alkylphenol amphiphiles) for amphiphiles to form stable steric layers around asphaltenes. We also found additi onal acidic side groups of amphiphiles could further improve the amphi phile's ability to stabilize asphaltenes. The effect of the molecular weight of alkane solvents on the amphiphile's ability to stabilize asp haltenes was also studied. The successive decline of the effectiveness of p-alkylphenol amphiphiles on asphaltene stabilization from dodecan e to pentane could be explained in art by the reduction of the asphalt ene-amphiphile attractive interaction. On the contrary, the extremely strong ability of p-alkylbenzenesulfonic acid amphiphiles to associate both asphaltenes and themselves made their effectiveness on asphalten e stabilization decrease with increasing molecular weight of alkanes.