FORMATION IN CRUDE OILS OF DIAMAGNETIC ASSOCIATES OF THE PARAMAGNETICCENTERS OF POLYAROMATIC STRUCTURES WITH VANADYL COMPLEXES

For a number of crude oils and resins and asphaltenes isolated from th em, EPR has been used to measure the concentrations of vanadyl complex es and asphaltene paramagnetic centres and also the spin-spin and spin -lattice relaxation times of asphaltene paramagnetic centres. The spin -spin and spin-lattice relaxation times were determined by means of co ntinuous saturation under rapid flowrate conditions. On the basis of t he data obtained, a model is proposed in which plane molecules of vana dyl complexes form associates with asphaltene molecules having plane p olyaromatic fragments. In this case diamagnetic complexes are formed w ith some asphaltene paramagnetic centres, which explains the dissimila r ratio of vanadyl and asphaltene paramagnetic centres in the oil.