Inhibition of Asphaltene Precipitation by Resins with Various Contents of Vanadyl Porphyrins

Comparative analysis of the composition and properties of heavy oils from various oil fields has revealed an inverse dependence of the asphaltene/resin ratio upon the vanadium content in resins. This indicates the diminishment of asphaltene precipitation ability with an increase in the content of vanadyl complexes in heavy oil resins. Experiments have shown that the addition of vanadyl porphyrins to resins enhances their inhibition activity toward asphaltene precipitation. For this purpose, vanadyl porphyrins have been concentrated by N,N-dimethylformamide extraction from resins and additionally purified by column chromatography. The obtained vanadyl porphyrin concentrate has been added to resins at the ratio of 1-5 wt %, and its influence on asphaltene stabilization has been further evaluated. Evaluation has been performed by measuring the optical density of deasphalted oil obtained by dilution of the crude oil with 20-fold excess of n-hexane, where resins with various contents of vanadyl porphyrins have been initially dissolved. The change in composition and properties of precipitated asphaltenes has been analyzed, and an increase in their absorbance, aromaticity, and degree of ring fusion with the growth of the vanadyl porphyrin content in resins has been demonstrated. Results have shown the efficiency of vanadyl porphyrins in resins as inhibitors of asphaltene precipitation.