Vanadium porphyrin complex

Concentrations of Vanadium Complexes, Porphyrin and Nonporphyrin, in Fractions of Four Crude Oils"... 

Vanadium Complexes and Porphyrins in Asphaltenes, J. Inst. Petrol. 

Valinomycin metal complexes, 969 Vanadium complexes acetylacetone exchange reactions, 380 1,4-diaza-l,3-butadiene, 209 dioxygen mononuclear, 321 hydrazido(2-), 148 hydroxamic adds, 506 phthalocyanines, 865 polypyrazolylborates, 248 porphyrins, 824 dioxygen adducts, 325... 

Asphaltenes may contain both porphyrin and nonporphyrin metals, depending upon the origin of the crude oil. Yen et al. (1969) characterized the vanadium complexes in a petroleum asphaltene by mass spectroscopy, optical spectroscopy, and ESR. Porphyrins (Etio and DPEP), acid-resistant porphyrin macrocycles of increased aromaticity (Rhodo), and nonporphyrins with mixed donor complexes were identified. Baker (1966) and Baker et al. (1967) extracted porphyrins from Boscan crude oil asphaltenes and also found Etio and DPEP as the two major porphyrin series. These homologous series range in molecular weight by 7 to 18 methylene groups. Gallegos (1967) observed by mass spectroscopy that asphaltenes and maltenes from a Boscan crude oil had nearly identical porphyrins in terms of mass distribution. 

Vanadyl porphyrins, VOP, mentioned above [see (5)] have been used as precursors for nonoxo vanadium(rv) porphyrins, [VPX2] (P = OEP, TPP, TMTP, TPTP X = Cl or Br). EXAFS at the Br K-edge has been used to coirfirm the trans configuration of X atoms in the complexes. The bare atom renders the compounds extremely reactive and one theory is that they could act as precursors in the synthesis of complexes formed during coal conversion. ... 

The amazing richness of vanadium complexes in crude oil and shale raises the obvious questions of where these vanadium complexes come from and what their biogenic source is. It is generally believed that the vanadium porphyrins result from the incorporation of vanadium in porphyrin structures originating from chlorophyll. (The reader is re-... 

Although there are obvious differences in the concentrations of the organic vanadium complexes found in the shallow and deep drill cores, the nature of the vanadium complexes present appeared to be virtually identical, as shown by high pressure liquid chromatography (C18 column, methanol solvent at 3 cc/min) of the vanadium porphyrin fractions extracted from core samples taken at depths of 90-92 m and 29-31 m. It would clearly be desirable to extend such studies to samples taken from much greater depths in the Toolebuc formation. 

Figure 10,1. Key types of vanadium complexes in petroleum (a) porphyrins, (b) mixed ligands such as N2O2 type, the -ketimines, (c) pseudoaromatic pheophorbides such as a bacterio-chlorophyll (the outer conjugation is interrupted, but still belong to the diaza-ld-annulene system), and (d) highly aromatic porphins such as the dehydrogenated product of m-a-naphylporphyrin, which was identified in Nonesuch shale. Type (a) is found in all petroleum. Types (b), (c) and (d) are commonly referred to as the nonporphyrin type of vanadium...

With drastic variations in sediments, composition as well as types of vanadium complexes vary. Even within a series of samples there is a noticeable variation of the vanadium complexes. For example, as the age or the depth of the fossil remains increases, a transformation of the porphyrin types from philo to etio takes place. This is merely one example of the large variety of reactions and transformations occurring in petroleum as well as other bituminous substances. The study of such effects would reveal much knowledge concerning the migration, maturation, and transformation of a diversity of fossil remains. 

EPR spectra with hyperfine interaction assist in the identification of the porphyrin or nonporphyrin vanadium complexes in crude oil (Saraceno et al., 1961 Espinosa et al., 2001). The experimental parameter used in this identification is (chemical shift), which expresses chemical changes. This is calculated from the spectroscopic factors go[Ago = (2.0023 — g ) x 10 (Dickson Petrakis, 1974). The different values obtained experimentally for the g parameter represent structural differences in the distribution of the hgands around the VO2+ in complexes. 

Nickel and vanadium complexed with pyrrole nitrogen atoms in porphyrinic rings... 

In the heaviest fractions such as resins and asphaltenes (see article 1.2), metal atoms such as nickel and vanadium are found. They belong in part to molecules in the porphyrine family where the basic pattern is represented by four pyrrolic rings, the metal being at the center of this complex in the form Wi - or V0+ (< 3)... 

Porphyrin, octaethyl-, vanadium oxide complex cyclic voltammetry, 4, 399 <73JA5140)... 

No. 6 fuel oil contains from 10 to 500 ppm vanadium and nickel in complex organic molecules, principally porphyrins. These cannot be removed economically, except incidentally during severe hydrodesulfurization (Amero, Silver, and Yanik, Hydrode.suljurized Residual Oils as Gas Turbine Fuels, ASME Pap. 75-WA/GT-8). Salt, sand, rust, and dirt may also be present, giving No. 6 a typical ash content of 0.01 to 0.5 percent by weight. 

In addition to hydrocarbons, petroleum also contains compounds that consist of nitrogen, oxygen, and sulfur (in the minority) as well as trace amounts of metals such as vanadium, nickel, iron, and copper. Porphyrins, the major organometaUic compounds present in petroleum, are large, complex cyclic carbon structures derived from chlorophyll and characterized by the ability to contain a central metal atom (trace metals are commonly found within these compounds). 

No. 6 fuel oil contains from 10 to 500 ppm vanadium and nickel in complex organic molecules, principally porphyrins. These cannot be... 

Crude oil consists mainly of a mixture of paraffinic, naphthenic, and aromatic hydrocarbons with small amounts of metals-containing heterocyclic compounds. The most abundant metals found in oils are those contained in porphyrin or porphyrin-like complexes (nickel, copper, iron, and vanadium). These... 

Some of the metallic constituents were somewhat soluble in the propane-oil portion, but all tended to be concentrated in the asphaltic portion. Although vanadium (0.02% by weight in the original crude petroleum) was present in all fractions, the greater part was found in the cyclohexane and benzene fractions. From the similarity of the absorption spectra of the vanadium concentrates from petroleum and those of synthetic vanadium porphyrin complexes, Skinner arrived at the conclusion that vanadium compounds from the petroleum of the Santa Maria Valley Field in California exist as porphyrin complexes. Additional metallic constituents were detected by Skinner as these became concentrated in the various solvent fractions, including aluminum, titanium, calcium, and molybdenum. 

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