Adsorption of Virgin and Visbroken Residue Asphaltenes over Solid Surfaces. 1. Kaolin, Smectite Clay Minerals, and Athabasca Siltstone

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• 作者：Francisco Lpez-Linares ; Lante Carbognani ; Clementina Sosa-Stull ; Pedro Pereira-Almao ; Ronald J. Spencer
• 刊名：Energy & Fuels
• 出版年：2009
• 出版时间：April 16, 2009
• 年：2009
• 卷：23
• 期：4
• 页码：1901-1908
• 全文大小：361K
• 年卷期：v.23,no.4(April 16, 2009)
• ISSN：1520-5029

文摘

Adsorption of virgin and thermally cracked vacuum residue from Athabasca bitumen was recently reported, using synthetic macroporous kaolin as adsorbent. Following that work, this study addressed the adsorption properties of virgin vacuum residue from Athabasca asphaltenes and thermally cracked products from these over different solid substrates. Synthetic (macroporous kaolin) and natural reservoir materials (siltstone and montmorillonites) are the adsorbents studied. Thermally cracked asphaltenes (mild visbreaking process) were used as proxies for the organics that remain downhole after a thermally production process. Adsorption experiments were carried out with toluene solutions of the studied adsorbates, monitored via UV−vis spectrophotometry. The findings showed that asphaltene from Athabasca virgin vacuum residue and thermally cracked products derived from it interact to different extents with solid surfaces. Evidence suggested that molecular size of these fractions does not limit their adsorption over the natural materials. Relative sizes of asphaltenes were inferred from size exclusion chromatography separations. Adsorption uptake of asphaltene is not only dependent on the textural properties of the adsorbents, but also appears to be a function of the nature of the asphaltenes as indicated by results from experiments with the virgin and thermally cracked materials. Higher aromaticity and nitrogen content of the asphaltenes were observed to enhance their adsorption. It was found that adsorption is not governed by the surface area of the studied solids but depends primarily on the pore volume and pore diameter of the adsorbent, possibly indicating that adsorbed asphaltene provides a substrate for continued adsorption of like molecules until reaching either pore volume saturation or chemical equilibrium with their concentration in solution.