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Handbook of Size Exclusion Chromatography and Related ...

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Table 2 Elemental Characterization <strong>of</strong> Corbett Fractions<br />

Average number <strong>of</strong> atoms per molecule in<br />

Naphthene Polar<br />

Element Saturates aromatics aromatics Asphaltenes<br />

Carbon<br />

Paraffin chain 31 21 24 85<br />

Naphthene ring 14 17 18 29<br />

Aromatic ring 0 13 25 115<br />

Hydrogen 85 94 105 350<br />

Sulfur 0 0.5 1 4<br />

Nitrogen 0 0 1 3<br />

Oxygen 0 0 1 2.5<br />

Average molecular weight 625 730 970 3400<br />

Source: Ref. 99.<br />

betweenpolararomatics,whichthenmaybecomeasphaltenes(23,103–106).This<br />

association strongly impacts attempts to measure molecular size by SEC or<br />

colligative properties.<br />

There is considerable evidence that, contrary to the data in Tables 1<strong>and</strong> 2<br />

<strong>and</strong>muchpublisheddata,thesingleasphaltenemoleculeisactuallynolargerthan<br />

those<strong>of</strong>otherfractions.Figure1showsanSECchromatogram<strong>of</strong>abadlyoxidized<br />

Table 3 Distribution <strong>of</strong> Functional Groups in Fractions from Corbett Separation a<br />

Whole<br />

Concentration in fraction (M)<br />

Naphthene Polar<br />

asphalt Saturates aromatics aromatics Asphaltenes<br />

Ketones 0 0 0 0.11 Trace<br />

Carboxylic acids 0.027 0 0 0 0.034<br />

Anhydrides 0 0 0 Trace Trace<br />

2-Quinolone types 0.021 0 0 0.023 0.046<br />

Sulfoxides 0.019 0 Trace 0.12 0.09<br />

Pyrrolics 0.17 0 0 0.21 0.23<br />

Phenolics 0.035 0 0 0.055 0.075<br />

a Yield <strong>of</strong> fractions based on whole asphalt were saturates, 9.9%; naphthene aromatics, 25.3%; polar<br />

aromatics, 38.1%; asphaltenes, 21.6% loss (which should be added to polar aromatics), 5.1%.<br />

Source: Ref. 101.<br />

© 2004 by Marcel Dekker, Inc.

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