Chromatographic Isolation of Petroleum Vanadyl Porphyrins Using Sulfocationites as Sorbents

Abstract

A comparative analysis of the composition of vanadyl porphyrins isolated from heavy oil using two different sulfocationites has been carried out. As a source of vanadyl porphyrins, heavy oil of Volga-Ural basin characterized by a high vanadium content was used. The N,N-dimethylformamide extract of asphaltenes was derived from this oil and subjected for isolation of primary vanadyl porphyrin concentrate on a SiO2 column, which was then chromatographically purified with sulfocationite by our improved method. Strongly acidic cation-exchange resin and asphaltene sulfocationite recently developed in our laboratory were used as sulfocationites. According to ultraviolet–visible spectroscopy, both sulfocationites showed excellent applicability for purification, providing isolation of a broad (>50%) fraction of vanadyl porphyrins with higher spectral purity compared to results of conventional methods. Results of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis showed that composition of isolated vanadyl porphyrins depends upon the chemical nature of sulfocationite. Despite the same range of vanadyl porphyrin homologues (C26–C40, with maximum falling on C32) isolated by both sulfocationites, purification with asphaltene sulfocationite resulted in a 1.4-fold decrease in the content of the most abundant DPEP type of vanadyl porphyrins, with a corresponding 1.1–1.9-fold increase in the content of the rest of the types. It was also established that, when purification is accomplished, a significant part of the same vanadyl porphyrins still remains in the column, which can be explained by their associations with non-porphyrin components of the oil.

High-Field (3.4 T) ENDOR Investigation of Asphaltenes in Native Oil and Vanadyl Complexes by Asphaltene Adsorption on Alumina Surface

“…It could be assumed that asphaltenes with a more condensed structure and lower VP content are adsorbed on alumina. It agrees with the previously revealed trend of inverse dependence of the concentration of FR on the content of vanadyl complexes (see papers [19,21,22] and references therein). Alternatively (or additionally), a formation/disappearing of new stable radicals, in which EPR spectra are indistinguishable from the initial ones, as a result, for example, of chemical bond opening/chemical bonding and oxidation processes upon adsorption [60,61], could be supposed.…”

“…In general, petroleum porphyrins exist in homologous manifolds of several structural classes and can manifest great structural diversity. A series of papers nowadays is devoted to the determination of various vanadyl porphyrins (VP), to application of state-of-the-art massspectroscopic techniques for that purpose as well as to the development of different pathways of the effective vanadyl extraction [1,4,[16][17][18][19][20][21][22][23]. Dickie and Yen were the first to suggest that, having many of the same interactive groups as asphaltenes, petroporphyrins could also play a role in asphaltene self-assembly, adsorption, and phase separation [24].…”

Advances and Challenges in the Molecular Characterization of Petroporphyrins

“…Furthermore, purification of asphaltene sulfocationite resulted in a 1.1-1.9-fold increase in non-DPEP vanadyl porphyrin structures. 100 Application of the sulfocationite porphyrin purification method to resins and asphaltenes from three heavy oils of different origins and vanadium contents combined with MALDI TOF-MS identified DPE, Etio, Di-DPEP, and Rhodo-DPEP vanadyl porphyrins across all samples, with resins and asphaltenes from the same oil exhibiting significant differences in the group composition of purified vanadyl porphyrins. 101…”

“…98 Vanadyl porphyrins isolated from asphaltenes derived from a heavy oil from the Volga-Ural basin were purified based on a novel strong acid cation-exchange resin and asphaltene sulfocationite method. 99 Subsequent characterization of purified porphyrins by MALDI ToF-MS showed that the composition of isolated vanadyl porphyrins was dependent on the chemical nature of sulfocationite. Furthermore, purification of asphaltene sulfocationite resulted in a 1.1−1.9-fold increase in non-DPEP vanadyl porphyrin structures.…”

Impact of Asphaltenes on the Adsorption Behavior of Petroleum Vanadyl Porphyrins: Kinetic and Thermodynamic Aspects

“…However, the abovementioned enriching approaches are insufficient to prepare pure petroporphyrins in one stage of chromatographic purification due to the extremely complex composition of polar petroleum fractions. This circumstance has forced researchers either to perform multistage chromatographic purification using conventional adsorbents such as silica gel or aluminum oxide or to develop alternative stationary phases exhibiting increased selectivity toward petroporphyrins. ,− …”