10 Organometallic Complexes in Domestic Tar
Downloaded by NORTH CAROLINA STATE UNIV on May 6, 2015 | http://pubs.acs.org Publication Date: December 1, 1978 | doi: 10.1021/ba-1978-0170.ch010
Sands J. F. BRANTHAVER and S. M. DORRENCE U. S. Department of Energy, Laramie Energy Research Center, Laramie, WY 58102
The vanadium, nickel, and porphyrin contents of organic materials derived from a number of domestic tar sands have been determined. Some of the tar sands were extracted in a Soxhlet extractor, while others were extracted at room temperature by a series of solvents of increasing polarity beginning with n-heptane and ending with pyridine. Most of the samples were from outcrops of various Utah deposits, although some core samples were investigated. Porphyrins were found in some of the outcrops and cores. With one exception, materials having a high sulfur content also have a ratio of vanadium to nickel of greater than unity, while low-sulfur materials have vanadium-to-nickel ratios of less than unity.
"pvomestic tar sands are known to contain over 30 billion barrels of oil, -*-^most of which occurs in a few deposits in Utah (I). The Laramie Energy Research Center ( L E R C ) is investigating many of these deposits in order to determine the potential for exploitation of this resource. One of the properties of fossil fuels of interest to refiners is metal content. Vanadium in particular is troublesome in refinery operations (2). In some crude oils it occurs in concentrations up to 1000 ppm (3). Of the other metals in petroleum, only nickel is known to be present in concentrations approaching that of vanadium. These two metals are complexed with poiphyrins and other ligands, the exact nature of which is unknown (4). Crude oils that are high in sulfur are usually high in vanadium (5), and it is interesting to determine whether or not this criterion also applies to tar sands. This chapter not subject to U.S. copyright. Published 1978 American Chemical Society In Analytical Chemistry of Liquid Fuel Sources; Uden, P., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1978.
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ANALYTICAL CHEMISTRY OF LIQUID FUEL SOURCES
Downloaded by NORTH CAROLINA STATE UNIV on May 6, 2015 | http://pubs.acs.org Publication Date: December 1, 1978 | doi: 10.1021/ba-1978-0170.ch010
Experimental Some of the tar sands were extracted exhaustively with benzeneethanol (3:1) in a Soxhlet extractor to yield organic materials, and only those materials so obtained will be subsequently referred to as bitumens. This process does not remove all organic materials from some tar sands, and so another method of extraction was used. In the alternate pro cedure, tar sands first were pulverized in a mortar and pestle. Then the sample was transferred to Erlenmeyer flasks and treated with suc cessive volumes of η-heptane until less than 25 mg of material was dis solved. Each volume of heptane solution was filtered on a sintered glass funnel (coarse porosity), and the heptane then was removed. After hep tane was observed to dissolve little material, the solvent was changed to benzene and after this to a mixture of benzene-methanol (1:1). Finally, the sands were extracted with several portions of warm pyridine. Vanadium and nickel concentrations were determined colorimetrically by forming tungstovanadic acid and nickel dimethylglyoxime accord ing to the procedure of Bean (3). Measurements were performed using a Beckman Acta M-IV spectrophotometer. Porphyrin analyses were done by the direct intergral technique of Bean and Sugihara (6) using a Beckman DK-2 spectrophotometer. Analyses for sulfur and nitrogen were carried out by the Technical Services Section of Laramie Energy Research Center. Asphaltenes were obtained by contacting bitumens with large volumes of heptane. Results and Discussion Compared with a high-sulfur, metal-rich crude oil from the Boscan field of Venezuela (3), the vanadium contents of most of the tar sand bitumens (see Table I) are relatively low, particularly in view of the high sulfur values of some of the bitumens. If tar sand bitumens are the residues of crude oils which have lost their light ends, it might be expected that metals, which are always concentrated in the heavier Table I.
Analyses of Various Tar Sand Bitumens μτηοΐββ/ς
Boscan, Venezuela, crude oil Battle Creek, W Y Asphalt Ridge, U T P.R. Spring, U T T a r Sand Triangle, U T Edna, C A Sant Rosa, N M Athabasca, A l t a .
"y
NÎ
V/Ni
22 2.8 0.7 1.1 3.8 1.9 0.5 4.9
2.0 0.8 1.1 1.8 1.2 2.5 0.4 1.5
11 3.5 0.6 0.6 3.2 0.8 1.2 3.3
Vanadyl Por phyrin, μτηοίβε/ς 10 0.5
