Characterization of Athabasca asphaltenes separated physically and chemically using small-angle X-ray scattering

• Author / Creator

  Amundarain, Jesus

• Athabasca asphaltenes were characterized using small-angle X-ray scattering (SAXS) with synchrotron radiation. Two methods were used to separate asphaltenes from Athabasca bitumen. Conventional chemical separation by precipitation with n-pentane, and physical separation realized by passing bitumen through a zirconia membrane with a 20 nm average pore size. The Athabasca permeates and chemically separated samples were dispersed in 1-methylnaphtalene and n-dodecane, with temperature and asphaltene concentration ranges of 50-310 °C and 1-8 wt. %, respectively. Two approaches were also taken in the analysis of the SAXS emissions. A model-independent approach provided radii of gyration and scattering coefficients. A model-dependent fit provided size distributions for asphaltenes aggregates assuming that they are dense and spherical. Physically and chemically separated asphaltenes showed significant differences in nominal size and structure, and their structural properties exhibited different temperature dependencies. The results challenge the merits of using chemically separated asphaltene properties as a basis for asphaltene property prediction in crude oil/bitumen.

• Subjects / Keywords

  • Asphaltenes
  • Small-angle X-ray scattering (SAXS)
  • Particle size distribution
  • Radius of gyration
  • Scattering coefficient

• Graduation date

  Fall 2010

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3B34H

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.