Comparative Study of Resins and Asphaltenes of Heavy Oils as Sources for Obtaining Pure Vanadyl Porphyrins by the Sulfocationite-Based Chromatographic Method

• Published in: Energy & fuels 2018-12, Vol.32 (12), p.12435-12446
• Main Authors: Mironov, Nikolay Alexandrovich, Abilova, Guzalia Rashidovna, Borisova, Yulia Yurevna, Tazeeva, Elvira Gabidullovna, Milordov, Dmitry Valerevich, Yakubova, Svetlana Gabidullinovna, Yakubov, Makhmut Renatovich
• Format: Article
• Language: English
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/acs.energyfuels.8b03411

The resins and asphaltenes of three heavy oils differing in origin (Permian and Carboniferous) and vanadium content (0.025–0.165 wt %) have been studied as sources for isolation of spectrally pure vanadyl porphyrins by sulfocationite-based chromatographic method developed by us recently. This method consists of removing the low polar nonporphyrin components from the resins or DMF extract of asphaltenes on SiO2-column followed by chromatographic isolation of vanadyl porphyrins on the sulfocationite. The asphaltenes were revealed to be a more promising source of vanadyl porphyrins because they possess ≥5 times higher content of vanadium, provide better accumulation of vanadyl porphyrins during deposition extraction by N,N-dimethylformamide, and are less contaminated by low polar nonporphyrin compounds capable of coeluting with vanadyl porphyrins through the sulfocationite column. According to matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy, DPEP vanadyl porphyrins were found to be the most abundant type for all studied samples (34.1–54.5%). Rhodo vanadyl porphyrins belong to minor components (3.3–8.7% for each subtype) while Etio and Di-DPEP types take the intermediate position (9.8–28.7%). The resins and asphaltenes of the same oil showed significant difference in the group composition of purified vanadyl porphyrins. For the resins, a ∼1.3-fold decreased content of DPEP vanadyl porphyrins was found, which was compensated by a ∼1.5- and/or ∼1.8-fold increase in the content of Etio and Rhodo vanadyl porphyrins, respectively. However, this change in the composition of vanadyl porphyrins is not accompanied by a notable change of their average molecular weight despite the fact that increased concentration of more substituted (i.e., more hydrophobic) vanadyl porphyrins could be expected for less polar resins. This fact was interpreted in favor of association of vanadyl porphyrins with nonporphyrin components of the oil.