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Thesis (Ph. D.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on June 18, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemical Engineering, Department of Chemical and Materials Engineering, University of Alberta. Includes bibliographical references.

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The demand for a new solvent to treat oilsands was behind the purpose of this project; molecular dynamics simulation was used in this study. Supercritical water, supercritical carbon dioxide and other selected organic solvents in their supercritical state were studied. Meso-tetraphenyl porphyrin (H2TPP) and Octaethyl porphyrin (H2OEP) are the porphyrin model compounds and, 4-Bis-(2-pyren-1-yl-ethyl)-[2, 2] bipyridinyl (PBP) is the asphaltene model compound. A solubility parameter approach was used to infer the solubility of model compounds in the supercritical fluids. First, the solubility of water, carbon dioxide, 4 selected organic solvents, and the three model compounds were computed using molecular dynamics simulation and compared with experimental results. The computed solubility parameters showed that the model compounds would dissolve in supercritical water (22.5 MPa and 645-655 K) but exhibited no solubility in supercritical carbon dioxide. / Chemical Engineering

Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on May 20, 2010). Includes bibliographical references.

In this work, different optical techniques have been explored to study and characterize crude oil and its asphaltene. Crude oil is extremely complex fluid used to produce fuel for a wide range of applications. The characterization of this fluid is key for optimum operations in the oil and gas industry. First, we demonstrate the application of gold nanorods in characterizing a different set of crude oils. We utilize the high sensitivity of the Localized Surface Plasmon Resonance (LSPR) of the nanorods to the surrounding environment to measure the crude oil refractive index. We immobilized the nanorods on a glass substrate and took the measurement in a reflection configuration. The setup and the nanorods were calibrated using different fluids with known refractive index, and a sensitivity of 247 nm/RIU and a resolution of 0.013 RIU have been achieved. In addition to the simplicity of this approach, it has eliminated the absorption issue and made it possible to measure high optical density crude oils with typical Visible-NIR wavelengths. Surface-Enhanced Raman Spectra (SERS) can also be measured. SERS can provide additional useful information, especially to some applications such as downhole fluid analysis, where confirmation of the hydrocarbons presence is necessary. In the second part of this work, we used Terahertz Time-Domain Spectroscopy (THz-TDS) to study the asphaltene in three different crude oils. THz-TDS has a feature of measuring the amplitude and time delay and consequently the refractive index and absorption coefficient spectra simultaneously. Our approach is based on measuring the THz signal from neat crude oil samples and comparing it with the THz signal after removing the asphaltene from the samples (maltene). The results show that the difference in the time delay and the peak amplitude between the neat oil and the maltene have a linear relation with the asphaltene content. The refractive index spectra of different asphaltenes show variation in the low THz frequencies and comparable spectra in the higher frequencies. The absorption of asphaltene was mild and no distinctive absorption feature was observed except for some narrow absorption peaks that we attributed to water molecules adsorbed on the asphaltene. / Graduate

Microfluidic H-cells and surface enhanced Raman spectroscopy are capable of analysing the asphaltene content of petroleum. An H-cell is a microfluidic device that exploits the non-turbulent flow of fluids within a micrometre-dimensioned channel. Diffusive separation in an H-cell permits a liquid that is miscible with the sample matrix to be used as an extractant. It was demonstrated that n-hexane can be used as extractant to obtain an asphaltene-free fraction of oil. The difference between the UV-Vis adsorption spectra of the asphaltene-free oil and the oil sample can then be used to estimate its asphaltene content. This has been demonstrated for a range of oils with asphaltene content between 1-30% and API gravity values between 40-10°, thus liquid petroleum and bitumen can be rapidly assayed by an H-cell; similarly, asphaltene and carboxylic acid content of oil can be determined simultaneously when methanol is used as extractant. The results were shown to be comparable to assays achieved via the ASTM D4124 and ASTM D974 methods respectively. For the first time it was demonstrated that surface enhanced Raman spectroscopy, using a gold substrate and illumination at 514 nm, can detect extremely low concentrations of asphaltene. This was shown to be achievable for asphaltene and related materials at concentrations of 0.001 ppm. In addition, data also demonstrated that the core of the Raman-responsive units within asphaltene have crystallite sizes equivalent to the Raman-responsive units in kerogen (~3 nm). Both methods provide technological advances because they make it possible to detect asphaltene in small sample volumes, using smaller footprint instrumentation. The H-cell method would be extremely useful for appraising oilfield potential, record the attenuation of oil-spills and provide frequent geochemical data that can monitor these at point of need. Similarly, the SERS technique widens the field of application into areas previously inaccessible to current techniques such as the effect of low concentrations of asphaltene-like materials in ecological and living systems.

A Surface Forces Apparatus (SFA) was used in this study to investigate the fundamental surface forces in oil sand processing research. Asphaltene coated surfaces were chosen as the research topic due to the critical role of asphaltenes in oil sands processing, from bitumen extraction, froth treatment to tailings treatment. To mimic the real surface state in industry processing, dip-coated asphaltene surfaces were prepared for surface force experiments. In this study, a SFA 2000 was used to determine intermolecular and surface forces of asphaltene in organic solvents (toluene and heptane). The force vs. distance curves, or so-called force profiles obtained provide valuable information on local material properties such as interaction energies, molecular conformation changes of the interacting asphaltene surfaces or films. Atomic force microscopy (AFM) was used to provide complementary information on the surface morphology of the prepared asphaltene surfaces. / Chemical Engineering

Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Dec. 11, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Chemicals and Materials Engineering, University of Alberta." Includes bibliographical references.