Judy Kung

Adsorption of Pentane Insoluble Organic Matter from Oilsands Bitumen onto Clay Surfaces

Abstract The effectiveness of commercial oilsands separation processes relies on the water wettability of the solids. Consequently, the interaction between the mineral and organic matter types present in oilsands is of interest. In this work, we report results related to the adsorption of a pentane insoluble fraction from bitumen on kaolinite and illite, the major clay types present in oilsands. We determined adsorption from toluene solution by illite and kaolinite and use a combination of spectroscopic techniques to probe the organic coated clay surfaces to different depths. The results are compared with similar data for equivalent natural fractions from oilsands.

A benchmark assessment of residues: comparison of Athabasca bitumen with conventional and heavy crudes

Abstract Compared to benchmark crude oils, bitumen does not respond well to conventional upgrading processes. In order to improve our understanding of this problem, we compare the chemical and physical properties of fractions from super critical fluid extraction of bitumen pitch with the corresponding fractions of residua from Venezuelan heavy oil, a Saudi Arabian light crude and a Chinese Daqing conventional crude. Relatively minor differences in chemical structure were observed between the corresponding residua fractions from Athabasca bitumen, Venezuelan heavy oil and Saudi Arabian light crude. Only the Chinese Daqing showed significant variance; this sample is much more aliphatic and has greater geometrical dimensions than the corresponding samples from the other residua. The end-cut from Athabasca bitumen pitch contained ultra-fine solids together with much higher levels of nickel, vanadium and nitrogen than the conventional crude end-cuts. These components are among the most intractable in upgrading and could be responsible for the problems encountered in bitumen upgrading, especially by catalytic processes.

Colloidal Clay Gelation: Relevance to Current Oil Sands Operations

Abstract Ultrafines are predominantly delaminated colloidal clays with dimensions <0.3 μm that exist naturally in oil sands and are released during conditioning of surface-mined ores. Critical concentrations of these ultrafines and the cations present in process water are capable of forming flocculated structures with a very high water holding capacity. During primary separation of bitumen these ultrafines are detrimental to recovery as a result of increased slurry viscosity as well as through slime coating of released bitumen. Disposition into tailings ponds eventually produces mature fine tailings (MFT) as a result of thixotropic gel formation that entraps coarser solids. The ultrafines concentration of ~3 wt% observed in MFT coincides with the critical gelation concentration determined for suspensions of ultrafines in salt solutions with cationic concentrations representative of that in pond water. This observation accounts for 100% of the water holding capacity of MFT and also explains why virtually no water is released once an MFT gel state has been formed. Here, we review earlier research in this area and identify the harmful effects of ultrafines in some current problematic ores.

The Comparison of Bitumens from Oil Sands with Different Recovery Profiles

Abstract It has been proposed that, regardless of origin, the recovery of bitumen from oil sands is related to its viscosity. Asphaltene and resin contents are known to affect the viscosity of bitumen. In this article we compare the composition of solvent-extracted bitumens from several Athabasca oil sands with very different recovery profiles. After careful removal of any associated mineral matter by ultra-centrifugation, each bitumen sample was separated into saturate, aromatic, resin, and asphaltene (SARA) fractions by an enhanced SARA technique. The individual components were then characterized by several complementary analytical techniques, including carbon, nitrogen, nitrogen, sulfur, size exclusion chromatography molecular weight (MWn) plus proton and 13C nuclear magnetic resonance spectroscopy. Based on this comparison, we see no correlation between the recovery of bitumen and its composition.

Production of Activated Carbon from Athabasca Oilsands Bitumen

Abstract The carbonization process of the pentane insoluble (end-cut) fraction from Athabasca oilsands bitumen in the presence NaOH has been investigated. Chemical activation produced carbon with a well-developed mesoporous structure and a much reduced sulfur content. The yield of the activated carbon increased, whereas sulfur content decreased with an increase in the NaOH load. Physical activation with carbon dioxide resulted in significant improvement in surface area. The properties of an activated carbon produced from end-cut were compared with those for carbon derived from fluid coke. Compared to fluid coke, end-cut is more suitable in the preparation of the carbon with low sulfur content and high mesopore surface area.

Characterization of a Gas Oil Fraction and Its Hydrotreated Products

Abstract In this work we explore the chemistry of a gas oil fraction in the mid-boiling range (433–483°C) and its products after hydrotreating at 375, 385, and 400°C. Each sample was fractionated by high performance liquid chromatography (HPLC) based on the elution times for saturate, mono-, di-, and poly-aromatic standards. The HPLC saturate fraction is practically free of aromatic components. The nominal mono- and di-aromatics fractions differ in that the former has a higher molecular weight and H/C ratio cbut lower aromaticity and heteroatom content. The H/C atomic ratios, aromaticities, and average structural parameters of the HPLC poly-aromatic subfractions are virtually the same. Regardless of their structural resemblances they differ substantially in their HPLC elution behavior. This can be attributed to the differences in their oxygen and, especially, nitrogen contents. Hydrogenation produced a significantly greater amount of saturate material having a higher H/C ratio than the original feed. A large part of this increase must result from dealkylation, saturation, or opening of aromatic molecules. This mechanism also produced nominally mono-aromatic compounds from the poly-aromatic species originally present. The effect of hydrogenation on heteroatoms was mixed. While the overall amount of nitrogen was reduced, its concentration in the poly-aromatic fractions actually increased. Overall, oxygen concentration in the product was not much affected by hydrogenation, except that its distribution became skewed towards the more easily eluted HPLC front-fractions. Both thiophenic and sulphide sulphur were significantly reduced in all of the separated fractions.