The Properties of Asphaltenes and Their Interaction with Amphiphiles

Abstract

The functional groups on asphaltene surfaces of two kinds of Chinese residue oil were analyzed by X-ray photoelectron spectroscopy (XPS). The ζ potential and electrophoretic mobility of asphaltene solutions and residue solutions were measured through phase analysis light scattering (PALS) technique. The ability to stabilize asphaltenes of two typical ionic amphiphiles, dodecyl benzene sulfonic acid (DBSA) and dodecyl trimethyl ammonium bromide (DTAB), were investigated. Karamay asphaltenes contain large amount of carboxyl and calcium and are negatively charged; whereas Lungu asphaltenes are rich in nickel, vanadium, and pyrrolic structures and are positively charged. DBSA has good ability to stabilize Lungu asphaltenes but has no effect on Karamay asphaltenes. Differently, DTAB has good ability to disperse Karamay asphaltenes but has no obvious effect on Lungu asphaltenes. It is concluded from these results that the charges might derive from the dissociation of metal ions and the deprotonation of acid groups (such as COOH, OH, and SH) or basic groups (such as pyridinic groups) on asphaltene surface. The electric property of asphaltenes plays an important role in the interaction between asphaltenes and amphiphiles. The negatively charged asphaltenes tend to be dispersed by cationic amphiphiles, whereas the positively charged asphaltenes tend to be dispersed by anionic amphiphiles.

Characterization of asphaltene isolated from low-temperature coal tar

“…These findings are consistent with other reported results [22,23]. Nevertheless, it is difficult for XPS to make it clear whether the types are occurring in aromatic or in non-aromatic compounds [32].…”

“…This research result is in agreement with previous observations of the asphaltenes from residue and crude oil [21,22,34]. For the quaternary-nitrogen, Kelemen et al [33] considered it as protonation of pyridinic-nitrogen associated with carboxyl oxygen or hydroxyl group through a H-bridge, whether or not it is adjacent to or near the related groups.…”

“…The research results are consistent with the C 1s spectrum analysis. In contrast to this, the asphaltenes from residue oils [22] are rich in carbonyl or carboxylic acids and ester groups.…”

“…From the elemental analysis, it can be concluded that the asphaltene from LTCT contains higher heteroatoms, particularly oxygen, but slightly lower sulfur than other asphaltenes from crude oil and petroleum [8,9,11,19,22]. The analysis confirms that contents of heteroatoms (S, N and O) in asphaltenes significantly differ depending on their origins [8][9][10][11][12][18][19][20]22]. Furthermore the asphaltene from LTCT contains lower H/C ratio, which implies a higher aromatic degree even if it may be due also to its higher heteroatom contents.…”

“…The results showed that the nitrogen containing compounds were mainly of pyridinic and pyrrolic types. The carbon and atom (S, O, and N) forms of the asphaltenes from two kinds of Chinese residue oil were obtained by using the XPS technique [22]. The results indicated that C-C and C-H species were the main types in the samples.…”