Characterization of nickel and vanadium compounds in tar sand bitumen by petroporphyrin quantitation and size exclusion chromatography coupled with element specific detection

Previously, we have examined the Ni and V in heavy crude oils, residua, and processed products by several metal speciation techniques to ascertain molecular structure and processing behavior. Two classes 01 metal compounds were found -- metallopetroporphyrins and metallo-nonporphyrins - each having unique reactivity during processing. In efforts to better understand the binding of metals in the oil medium, we have now examined Ni and V in tar sand bitumens. The bitumen was solvent extracted from the sand matrix and was separated by column chromatography to quantitate petroporphyrin content. The petroporphyrin contents ranged from virtually none to over 36% of the total metals. Asphalt Ridge (Utah) nas primarily Ni petroporphyrins; Big Cliffy (Kentucky) and Athabasca (Canada) have primarily V petroporphyrins: Arroyo Grande and McKittrick (California) have roughly equal amounts of both types; and Sunnyside (Utah) has virtually none of either. Size characteristic profiles (SEC-HPLC-ICP) were generated for the extracted bitumens. The profiles are generally bimodal in shape anc resemble several different specific heavy crude oils and residua. For examples, Arroyo Grande and McKittrick appear to be similar to Kern River (California) 650°F+ residuum while Athabasca resembles Morichal (Venezuela) 650°F+ residuum. These results will be discussed in terms of generalized profile and petroporphyrin behavior.