Asphaltene Adsorption onto Acidic/Basic Metal Oxide Nanoparticles toward in Situ Upgrading of Reservoir Oils by Nanotechnology

详细信息    查看全文

• 作者：Negahdar Hosseinpour ; Abbas Ali Khodadadi ; Alireza Bahramian ; Yadollah Mortazavi
• 刊名：Langmuir
• 出版年：2013
• 出版时间：November 19, 2013
• 年：2013
• 卷：29
• 期：46
• 页码：14135-14146
• 全文大小：606K
• 年卷期：v.29,no.46(November 19, 2013)
• ISSN：1520-5827

文摘

The effects of surface acidity and basicity of metal oxide nanoparticles on the thermodynamics of asphaltene adsorption were studied. Three different categories of metal oxides/salts with acidic (WO₃ and NiO), amphoteric (Fe₂O₃ and ZrO₂), and basic (MgO and CaCO₃) surfaces were synthesized, and their textural, structural, and acid鈥揵ase properties were characterized. Asphaltenes were extracted from a dead oil sample and characterized by X-ray powder diffraction and Fourier transform infrared spectroscopy. The acid and base numbers of the asphaltenes were measured. The nanoparticles were added to the asphaltene鈥搕oluene solutions, and the amount of adsorbed asphaltene was obtained through centrifugation followed by UV鈥搗is spectroscopy of the supernatant liquid and temperature-programmed oxidation analysis of the precipitated solid. The concentrations of organic acid and base groups in the asphaltenes are 2.75 and 12.34 mg of KOH/g, respectively, indicating that the asphaltenes are more basic in nature. Isotherms of the asphaltene adsorption onto the six metal oxides/salts fit the Langmuir model closely. The asphaltene adsorption capacity of the nanoparticles is 1.23鈥?.67 mg/m² and decreases in the order of NiO > Fe₂O₃ > WO₃ > MgO > CaCO₃ > ZrO₂, concomitant with the synergetic effects of acidity and the net charge of the surfaces. High-resolution transmission electron microscopy illustrates that the asphaltenes are spread out over the surfaces with no short-range/long-range order. The adsorption of the asphaltenes onto the six samples is exothermic and spontaneous with the Gibbs energy change of 鈭?7.80 to 鈭?8.79 kJ/mol at 25 掳C. The absolute value of the enthalpy change of the adsorption is calculated to be within the range of 5鈥?0 kJ/mol. Acid鈥揵ase interaction and electrostatic attraction seem to be the dominant forces contributing to the adsorption of the asphaltenes onto the metal oxide/salt surfaces.