Speros E. Moschopedis

Investigation of asphaltene molecular weights

Abstract The molecular weights of asphaltenes, as determined by vapour-pressure osmometry, vary considerably and are dependent upon the nature of the solvent as well as the temperature. The data are interpreted in terms of association (of the asphaltene units) in solvents of low dielectric constant and dissociation in solvents of high dielectric constant. Data derived by means of a viscometric method yield inconsistent values for asphaltene molecular weights, and recognition of these inconsistencies causes some revision of the theory of the physical structure of petroleums, bitumens and asphalts.

Investigation of hydrogen bonding by oxygen functions in Athabasca bitumen

Abstract A study has been made of the role played by the oxygen functions in hydrogen-bonding interactions which occur between the asphaltene and resin entities of Athabasca bitumen. The results show that hydrogen bonding occurs readily between these fractions and allows feasible representation of the manner by which the asphaltenes are peptized by the resins.

Thermal decomposition of asphaltenes

Abstract The thermal decomposition of Athabasca asphaltene at relatively low ( 350 °C) temperatures are attained.

Oxygen functions in asphaltenes

Abstract Acetylation of asphaltenes shows that 40–60% of the oxygen present in these materials is accessible to acetylation. Infrared spectroscopic examination of the products indicates that this oxygen exists as phenolic hydroxyl groups and that a considerable portion of these groups may occur as collections of two or more functions on the same aromatic ring or on adjacent peripheral sites, or sites adjacent to a carbonyl function, in a condensed aromatic system.

Oxidation of a bitumen

Abstract Oxidation of a bitumen with air or oxygen in the presence of a diluent significantly increases the asphaltene content and noticeably reduces the asphaltene solubility. It is suggested that one of the main factors influencing the solubility of the asphaltenes, aside from possible polymerization of asphaltenes and resins, is incorporation of oxygen groups, e.g. hydroxyl, into the asphaltenes, and consequent changes in polarity sufficient to influence asphaltene deposition.

Influence of metal salts on bitumen oxidation

Abstract Oxidation of bitumen with air or oxygen at various temperatures significantly alters the composition of the material and markedly reduces asphaltene solubility. Similar and, in many instances, more noticeable effects are produced in the presence of metal salts. Throughout the various processes, oxygen incorporation usually occurs into those fractions which are relatively high in hetero-atom (nitrogen, oxygen and sulphur) content. Spectroscopic examination of the products allows feasible representation of the predominant pathways of bitumen oxidation as well as possible modes of asphalt deterioration.

The effect of air blowing on the properties and constitution of a natural bitumen

Air blowing of a natural and vacuum-reduced bitumen causes marked changes in the properties and constitution of the material. The products are harder and have higher softening points than the original material and the changes in physical properties appear to be related to the asphaltene content which increases with the temperature and duration of the blowing process. Analytical data indicate that conversion of the original resins to asphaltenes and the formation of new resins from the oils occur simultaneously; the data also provide feasible representations of the pathways of bitumen maturation and asphalt deterioration.

Investigation of the carbonyl functions in a resin fraction from Athabasca bitumen

Abstract Infrared and chemical studies of the resin fraction isolated from Athabasca bitumen indicate that oxygen in these fractions exists predominantly as ester functions. Evidence for this was obtained from hydrolysis, acetylation and methylation reactions.

Use of heavy oils (and derivatives) to process coal

Results of studies to determine the effect of process parameters such as temperature, pressure, and reaction time on the extent of coal conversion and on product distribution are reported. Various solvents, e.g. Athabasca bitumen, were used to solubilize coal, and conversion yields under noncatalytic and catalytic hydrogenation conditions indicated that conversion increased from 10 to 24% in coal solvation to 30 to 40% in the catalytic hydrogenation. Conversion studies with Great Canadian Oil Sands Ltd. (GCOS) bitumen and coker gas oil showed that the conversion yield constantly increased with increasing temperature for coal/bitumen processing while reaching a maximum yield at 400/sup 0/C and then dropping dramatically to near zero conversion for coal/coker gas oil conversion. Optimum conversion conditions were established to be reaction for 60 min at 400/sup 0/C at a pressure of approximately 1000 psig. Analyses of solid, liquid, and gases are presented for samples used in studies of the different process parameters. (BLM)

The production of low-sulphur liquids and coke from Athabasca bitumen

Abstract Hydrocracking of the Athabasca bitumen using a batch process produces liquid fuel streams that are highly aromatic. The results suggest that the use of hydrogen causes stabilization of the reactive intermediates rather than saturation of the thermal products. Furthermore, the liquid products are low in sulphur and asphaltics; coke with less than 2.5% sulphur is also produced.