engleski

DOSY NMR spectroscopy in the analysis of complex oil mixtures

Crude oil, its residues and products are one of the most complex compound mixtures in nature. Over the past couple of years, one of the main goals in petroleum industry has been to transfer heavy crude oil residues into light crude oil distillates. Asphaltenes, which are the heaviest and least reactive molecules in crude oils, cause many problems during transport and production. Owing to complex asphaltene structures, their characterization posts a major challenge in petroleum industry. In this research, concentration dependent diffusion measurements have been performed to determine the lowest aggregation concentration of asphaltenes and influence of magnetic field strength on aggregation process. Asphaltene components were separated by DOSY NMR technique according to their different diffusion coefficients. Their hydrodynamic radii and molecular weight were then estimated by using Stokes-Einstein equation. Changes in diffusion coefficients reflected the formation of different asphaltene types. It is expected that the presented results will contribute to better understanding of asphaltene aggregation process.

asphaltene aggregation ; diffusion coefficients ; DOSY NMR spectroscopy ;

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