Electron spin resonance study of the kerogen/asphaltene vanadyl porphyrins: air oxidation

Thermal behavior of vanadyl porphyrins was studied by electron spin resonance during heating of the kerogens isolated from the La Luna (Venezuela), Maganik (Montenegro) and Serpiano (Switzerland) bituminous rocks at 150 and 250°C for 1 to 20 days in the presence of air. During the thermal treatment...

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Bibliographic Details
Published in:	Fuel (Guildford) Vol. 80; no. 5; pp. 635 - 639
Main Authors:	Premović, P.I., Tonsa, I.R., Pajović, M.T., Lopez, L., Monaco, S.L., Đorđević, D.M., Pavlović, M.S.
Format:	Journal Article
Language:	English
Published:	Oxford Elsevier Ltd 01-04-2001 Elsevier
Subjects:	Applied sciences Crude oil, natural gas and petroleum products Electron spin resonance Energy Exact sciences and technology Fuels Kerogen Petroleum products, gas and fuels. Motor fuels, lubricants and asphalts Vanadyl porphyrins South America Venezuela Asia United States America Kentucky Israel North America Dead Sea Electron spin resonance Vanadyl porphyrins Kerogen Asphaltene Vanadyl Pyrolysis Heat treatment Thermal behavior Vanadium Oil industry Asphalt Bituminous rock Porphyrin Coal Oxidation Electron paramagnetic resonance Comparative study
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Summary:	Thermal behavior of vanadyl porphyrins was studied by electron spin resonance during heating of the kerogens isolated from the La Luna (Venezuela), Maganik (Montenegro) and Serpiano (Switzerland) bituminous rocks at 150 and 250°C for 1 to 20 days in the presence of air. During the thermal treatment of the kerogens the vanadyl porphyrins' resonance signals decrease monotonically and become quite small after six days of heating. Concomitantly, new vanadyl signals appear, and, at longer heating times, dominate the spectrum. It is suggested that the secondary vanadyl species must have been formed from vanadyl porphyrins. Similar conversion of vanadyl porphyrins are observed under the same experimental conditions for the asphaltenes extracted from the La Luna and Serpiano rocks, and the floating asphalt from the Dead Sea (Israel). A comparison of the spin-Hamiltonian parameters for vanadyl porphyrins and vanadyl compounds obtained during pyrolysis of the kerogens/asphaltenes suggests that these are of non-porphyrin type. For comparison, a study was conducted on the Western Kentucky No. 9 coal enriched with vanadium (up to 800 ppm) from six mines. All coal samples show only the presence of predominant vanadyl-non-porphyrin compounds similar to those generated through laboratory heating of the kerogens/asphaltenes in air. In addition, some samples also contain a minor amount of vanadyl porphyrins.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0016-2361 1873-7153
DOI:	10.1016/S0016-2361(00)00141-1