Abstract
In a previous communication, it was shown that asphaltene content was increased in the presence of aluminum trichloride.
The present paper represents a further facet of a structural analysis cf the consti-tuents of asphalt and a systematic investigation into the mechanism of asphaltene increase. A detailed structural investigation by nuclear magnetic resonance spectroscopy has been made possible by introducing a new parameter, branchiness ratio (k).
The mechanism of asphaltene increase has been studied from the chemical structures within the asphalt fractions before and after the catalytic reactions in the presence of aluminum trichloride.
The following results were obtained:
1) The mechanism of asphaltene increase occurs by the following reactions:
Aromatics isomerization→disproportionation Resins (I)
n×Resins addition polymerization → Asphaltenes (II)
Resins+Asphaltenes addition polymerization→ Asphaltenes (III)
In the absence of aluminum trichloride, reaction I and II do not occur.
2) Aromatic ring systems of asphaltenes become large and highly condenced in the presence of aluminum trichloride.
3) Aromatics having comparatively high condensed aromatic ring systems are easily consumed through reaction I.
4) In spite of aluminum trichloride addition, desulfurization does not occur at temperature 180°C.
