A Model Approach to Vanadium in Crude Oils and their Refining; FINAL

A Final Report is provided on the work carried out under the support of the indicated award. The work has been concentrated on identifying the reactivity characteristics of a variety of vanadyl compounds under the reducing and sulfur-rich conditions encountered by crude oil vanadyl impurities during the hydrotreating processes employed to upgrade crude oils. A wide range of new vanadium complexes have been discovered in this work, spanning the vanadium oxidation levels V(II)-V(IV) and metal nuclearities 1-15. New synthetic methods have been developed to molecular V/S compounds to model intermediates in the transformation of vanadyl porphyrins to V2S3 and V3S4 polymers. Included in these molecular products is a species in which VO2+ units are attached to a V/S core, a model system for the adsorption of VO2+ units from delegation of vanadyl porphyrins on the growing V2S3/V3S4 phase during hydrotreating. More recent work has concentrated on V/O chemistry and has been concerned with elucidating the reactivity of vanadyl species to aggregation, and identifying the nature and properties of the resulting species. A variety of new polynuclear clusters stabilized by carboxylate groups has been obtained. In one study, stepwise formation of a polyoxovanadate,[V15O36]5?, was accomplished from[VOCl4]2?, with V5 and V9 intermediates in the transformation being isolated and identified. This study provided unprecedented information on the pathway of polyoxovanadate assembly. New V5 and higher nuclearity polyoxovanadates were also obtained in this work. In addition, new synthesis methods have been developed to some known and many new mixed-metal V/Mo polyoxometalates to model supported oxidation catalysts involving V and/or Mo. All products obtained throughout the course of this work have been studied by a combination of X-ray crystallography, spectroscopy (1H, 51V NMR and EPR), physical methods (electrochemistry and magnetochemistry) and reactivity investigations