THE TRANSALKYLATION REACTION - ANALYTICAL TOOL FOR THE STUDY OF HEAVY CRUDE-OIL FRACTIONS - APPLICATION TO ASPHALTENES OF VARIOUS TYPES

We report the use of the transalkylation reaction (i.e. transfer of alkyl chains from the aromatic matrix to a light aromatic acceptor) as a tool for the analysis of different types of asphaltenes (Boscan, Arabian Light, Kirkouk, Maya and Duri). Because of the small quantity of sample available in the case of Duri asphaltenes, it was necessary to miniaturize the experimental procedure previously described. Using Boscan asphaltenes as a model, we demonstrate that in the transalkylation conditions previously retained, it is possible to obtain significant and reproducible results with a minimum amount of 25 mg of product. The results obtained, using these new conditions, from the different types of asphaltenes mentioned above are reported. A comparative study by direct pyrolysis of these asphaltenes (before and after transalkylation) proves that transalkylation is an efficient (transfer yield approximately 55%) and a selective reaction.