Year-Dependent Change of DNP Parameters in p-Difluorobenzene Suspension with Asphaltene

Abstract

Petroleum asphaltenes are the heaviest, most aromatic and most complex component of crude oil and asphaltenes are paramagnetic. Overhauser Dynamic nuclear polarization (ODNP) were performed to study samples of asphaltene/p-Difluorobenzene at 1.53 mT. p-difluorobenzen solvent with asfalten in three different concentrations waiting five years with oxygen removed have been stuied. Dynamic nuclear polarization parameters were determined by performing ODNP experiments again. The results of our studies and the calculated parameters, especially the coupling parameter, indicates that there were dipolar interactions between nuclei and free electron spins. These dipolar interactions indicate that, at the end of five years the the asphaltene micelles in suspension agglomerated and that make the molecule movements slower. The obtained dynamic nuclear polarization parameters were compared with their values in the literature and it was observed that the parameters decreased slightly with time.