Cold Lake resin fractions

Figure 7. GPC profiles of fractions of Cold Lake resins separated on anion exchange resin (IRA-904) and cation exchange resin (A-15) (a) acid fractions, (b) base fractions column and conditions same as in Figure 6...

Figures 7a and 7b are UV recordings, on the same combined columns (/i-Styragel 500 + 100 A) and at comparable concentrations, of the various resin fractions isolated in the separation of Cold Lake bitumen resins on an anion (Figure 7a) and a cation (Figure 7b) exchanger column. These curves were compared with MW measurements for these fractions by VPO from methylene chloride (Table VI). The various degrees of sample polydispersity of these fractions are noteworthy. However, these chromatograms have one striking feature that is revealed by the comparison of the base fractions from the cation exchanger with the curve of the nC5 eluent from the anion exchanger and, further, the relative positions of the acid and base curves with the MWs of these fractions obtained from VPO measurements in the same solvent.

The separations of resins and asphaltenes under comparable conditions done on the fractions from a common source—Athabasca (in some cases Cold Lake) bitumen—have confirmed a number of postulates that have appeared in the recent literature. 

Conversion (upgrading) of bitumen and heavy oils to distillate products requires reduction of the MW and boiling point of the components of the feedstocks. The chemistry of this transformation to lighter products is extremely complex, partly because the petroleum feedstocks are complicated mixtures of hydrocarbons, consisting of 10 to 10 different molecules. Any structural information regarding the chemical nature of these materials would help to understand the chemistry of the process and, hence, it would be possible to improve process yields and product quality. However, because of the complexity of the mixture, the characterization of entire petroleum feedstocks and products is difficult, if not impossible. One way to simpHfy this molecular variety is to separate the feedstocks and products into different fractions (classes of components) by distillation, solubility/insolubility, and adsorption/desorption techniques. For bitumen and heavy oils, there are a number of methods that have been developed based on solubility and adsorption. The most common standard method used in the petroleum industry for separation of heavy oils into compound classes is SARA (saturates, aromatics, resins, and asphaltenes) analysis. Typical SARA analyses and properties for Athabasca and Cold Lake bitumens, achieved using a modified SARA method, are shown in Table 1. For comparison, SARA analysis of Athabasca bitumen by the standard ASTM method is also shown in this table. The discrepancy in the results between the standard and modified ASTM methods is a result of the aromatics being eluted with a... 

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