Aggregated structure of flocculated asphaltenes

• Published in: AIChE journal Vol. 47; no. 1; pp. 206 - 211
• Main Authors: Savvidis, Theophylaktos G., Fenistein, Denis, Barré, LoïC, Béhar, Emmanuel
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.01.2001; Wiley Subscription Services; American Institute of Chemical Engineers
• Subjects: Applied sciences; Constitution and properties of crude oils, shale oils, natural gas and bitumens. Analysis and characteristics; Crude oil, natural gas and petroleum products; Energy; Exact sciences and technology; Fuels; Aggregation; Asphaltene; Crude oil; Flocculation; Deposit formation; Small angle X ray scattering; Sedimentation
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.690470120

Many petroleum processing problems are related to asphaltene flocculation. A detailed understanding of the colloidal structure of asphaltenes in oild can play a decisive role in improving processing facilities and/or operating conditions. The structure of the flocculated part of the asphaltenes of a crude oil far above the flocculation threshold was studied to understand its links with macroscopic phase separation. Asphaltene filtrations were performed using filter pore sizes from 0.025 to 10 μm. According to small angle X‐ray scattering (SAXS) spectra and density measurements, these extracted asphaltenes in toluene solutions did not have any physical differences. Measurements of nanometric sizes for the dispersed particles after dissolution in toluene show that micron‐size flocculated asphaltenes are strongly aggregated structures. Therefore, filtration experiments separate asphaltenes corresponding powders show spherically shaped aggregates of micron size. SAXS and USAXS techniques were used to investigate the internal structure of the asphaltene powder. The aggregates are clearly a compact organization of asphaltenic material. This dense structure explains why flocculated asphaltenes are subject to sedimentation, which induces the visible macroscopic phase separation.