The goal of this work is to provide characterization and a unified framework for understanding asphaltenes in crude oil. A fractionation technique that divides an asphaltene sample into different components based on polarity was developed. The morphology of the fractions varied from dense, shiny black particles that displayed a crystalline microstructure under SEM examination (the most polar fraction) to porous, dull-brown powders of a completely amorphous nature (the least polar fraction). Extensive studies using gel permeation chromatography, FTIR spectroscopy, and elemental analysis revealed no apparent structural differences between various fractions. However, substantially different dissolution characteristics were displayed by the fractions in a differential reactor with both toluene and an amphiphile/alkane micellar solvent. Fractions of higher polarity displayed lower dissolution rate constants and dissolved to a lesser extent than the lower polarity fractions. Analysis of asphaltene samples from eight different crude oils indicate that the fractionation technique may be a powerful tool for predicting the dissolution rate constant of an asphaltene sample and subsequently its difficulty of remediation. Further analysis of the fractions using ICP-90 and X-ray flourescence suggests that heteroatom content (especially metals such as iron, nickel, vanadium, aluminum, and nonmetals such as chlorine) plays a major role in determining the high polarity of asphaltenes. Treatment of the highest polarity fraction with the salt form of ethylenediamine tetraacetic acid (EDTA; a powerful metal-chelating agent) significantly increased dissolution rates when dodecyl benzene sulfonic acid (DBSA) was used in a heptane solution, suggesting that metal content may have a direct effect on dissolution rates. A slight increase in dissolution rate was observed with toluene as the solvent.

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Hydrocracking of Athabasca vacuum residue (AVR) was carried out in an autoclave using particle and fiber forms of NiO-WO3 zeolite-supported catalyst. AVR hydrocracking was performed at 400 °C at low and high H2 pressure of 70 and 365 psi, together with the corresponding control thermal cracking runs. The yield of the different products and the quality of the upgraded liquid was used to assess the catalyst performance. Similarity among energy consumption for the different samples suggested major thermal cracking endothermic reactions. In general, the catalytic runs provided better quality maltene product, whereas better quality product oil was only attained at high pressure. The catalytic runs at low H2 pressure gave the highest yield of combined asphaltenes and toluene insolubles. This yield, on the other hand, was the lowest for the fiber form at high H2 pressure. Simulated distillation results captured the superior performance of the fiber catalyst at high H2 pressure and showed ∼50% conversion of the residue. On the other hand, the zeolite particles showed poor performance at high pressure with only ∼30% residue conversion.

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