Vanadium in crude oils

The presence of vanadium and nickel in crude oils, especially as metal porphyrin complexes, has focused much attention in the petroleum refining industry on the occurrence of these metals in feedstocks (Reynolds, 1997). Only a part of the total nickel and vanadium in crude oil is recognized to occur in porphyrin structures (Table 3-5). In general, it is assumed that about 10% w/w of the total metal in a crude oil is accommodated as porphyrin complexes although as much as 40% of the vanadium and nickel may be present as metal porphyrin complexes in petroleum. 

Vanadium is present in crudes mainly in the +4 state (58). In fact, up to 50% of the total vanadium in crude oil can be found as V02+ in organometallic compounds such as porphyrins and naphthenates (59-63). During the cracking reaction in a FCCU, these compounds deposit V (probably in the form of VO+2 cations) on the catalyst surface. Then, after steam-stripping and catalyst regeneration, formation of V+5 surface phases occur. The effects of vanadium on FCC properties are more severe than any of the other metals present in petroleum feedstocks. In fact, vanadium causes an irreversible loss of cracking activity which is the result of a decrease in crystallinity, pore volume and surface area of the catalyst, Figure 5. 

Although metal ions are generally not very soluble in hydrocarbons, vanadium occurs at high levels in some crude oil products. What is there about vanadium in crude oil that enables this to occur ... 

Heated vaporization atomic absorption (HVAA) has been described extensively. HVAA differs from conventional atomic absorption in that an electrically heated device replaces the flame. The characteristics of HVAA are microliter sample consumption, sensitivity down to picogram quantities, and applicability to a wide variety of solutions. These characteristics have led to its widespread use. In petroleum analyses, this technique has been used to determine relatively high levels (ppm) of lead in gasoline, metals in used oils, and nickel and vanadium in crude oils (18). The Trace Metals Project has extended application of this technique to the determination of Be, Cd, Co, Cr, Mn, Mo, Sb, and V at the 10-ng/g level. 

Nickel and vanadium in crude oils have been studied extensively because of the presence of Ni and... 

Feathers exposed to the emissions within the Cu area were found to have very elevated concentrations of copper, arsenic and mercury. Arsenic is known to be a constituent of copper ores and can be easily converted to the volatile arsenic trioxide at smelting temperatures. The presence of large amounts of vanadium in crude oils that was reflected in the samples from the re/area is also well known. The concentrations of V in feathers were correlated with the distance of magpie territories from a certain section of the oil refinery (Dmowski and Golimowski, 1998). 

Elemental speciation using mass spectrometry in conjunction with ICPAES is a latest advance in atomic spectroscopy, which is becoming popular in analytical research labs. Mason et al. ExxonMobil Research and Engineering) show how linking ICP-MS to various liquid chromatographic techniques has enabled determination of ppm levels of metals in hydrocarbons to ppb level measurements in refinery effluent streams. Hyphenated ICP-MS techniques were used to provide speciation information on nickel and vanadium in crude oils and assist in development of bioremediation options for selenium removal in wastewater treatment plants. Similar ICP-MS technique without sample demineralization was used by Lienemann, et al. Institut Francais du Petrole) to determine the trace and ultra-trace amounts of metals in crude oils and fractions. 

Caumette, C., Lienemann, C.P. Merdrignae, 1., Bouyssiere, B., Lobinski, R., (2010), Fractionation and speciation of nickel and vanadium in crude oils by size exclusion chromatography ICP-MS and normal phase HPLC-ICP-MS, /. Anal. At. Spectrom. 

Silva, M.M., Damin, I.C.F. Vale, M.G.R., Welz, B., (2007), Feasibility of using solid sampling graphite furnace atomic absorption spectrometry for speciation analysis of volatile and non-volatile compounds of nickel and vanadium in crude oil. Talanta, 71, 349-359. 

The presence of vanadium in crude oil may, however, turn out to be profitable for the oil companies. If vanadium can be economically recovered from oil, then oil could become a major source of vanadium, a valuable metal with several important industrial uses, including the production of iron alloys and sulfuric acid. 

The petroleum industry faces the need to analyze numerous elements which are either naturally present in crude oil as is particularly the case for nickel and vanadium or those elements that are added to petroleum products during refining. 

Other compounds which may be found in crude oil are metals such as vanadium, nickel, copper, zinc and iron, but these are usually of little consequence. Vanadium, if present, is often distilled from the feed stock of catalytic cracking processes, since it may spoil catalysis. The treatment of emulsion sludges by bio-treatment may lead to the concentration of metals and radioactive material, causing subsequent disposal problems. 

Many metals occur in crude oils. Some of the more abundant are sodium, calcium, magnesium, aluminium, iron, vanadium, and nickel. They are present either as inorganic salts, such as sodium and magnesium chlorides, or in the form of organometallic compounds, such as those of nickel and vanadium (as in porphyrins). Calcium and magnesium can form salts or soaps with carboxylic acids. These compounds act as emulsifiers, and their presence is undesirable. 

Metals, such as nickel, vanadium, and sodium, are present in crude oil. These metals are concentrated in the heavy boiling range of atmospheric bottoms or vacuum residue, unless they are carried over with the gas oil by entrainment. 

Hodgson, G. W., 1954, Vanadium, Nickel and Iron Trace Metals in Crude Oils of Western Canada American Association of Petroleum Geologists Bulletin, Vol. 38, pp. 2537-2554. 

Generally, most resids and asphalt have 79 to 88% w/w carbon, 7 to 13% w/w hydrogen, trace to 8% w/w sulfur, 2 to 8% w/w oxygen, and trace to 3% w/w nitrogen. Trace metals such as iron, nickel, vanadium, calcium, titanium, magnesium, sodium, cobalt, copper, tin, and zinc occur in crude oils. Vanadium... 

DFCr systems appear to have the necessary metals tolerance to process residual oils and the abundant, cheaper, but heavily vanadium-contaminated, Venezuelan and Mexican crudes (1-4). Therefore, the dual function fluid cracking catalyst (DFCC) concept could lead to the generation of important catalysts for U.S. refineries should Middle East politics cause another sudden escalation in crude oil prices and availability. The concept is... 

Crude oil is composed primarily of hydrocarbon compounds. Organic and inorganic sulfur-, oxygen-, and nitrogen-containing species are also found in crude oil. Additionally, water, vanadium, nickel, sodium, and other metals may be present. 

Nickel and vanadium are the most abundant metals found in crude oil. Other metals, metalloids, and nonmetals including aluminum, arsenic, barium, calcium,... 

ESR has been used to characterize vanadium compounds in crude oil.354 873 In ESR spectra of [VO(TTP)], extrahyperfine structure from interactions with N atoms was detected in CS2 and CHCI3 glasses and the splitting constants A, A2 were calculated (2.9 0.05 and 2.8 0.05 G).517... 

Two groups of elements appear in significant concentrations in the original crude oil, associated with well-defined types of compounds. Zinc, titanium, calcium, and magnesium appear in the form of organometallic soaps with surface-active properties, adsorbed in the water-oil interfaces, and act as emulsion stabilizers. However, vanadium, copper, nickel, and part of the iron found in crude oils seem to be in a different class and are present as oil-soluble compounds (Reynolds, 1997). These metals are capable of complexing with pyrrole pigment... 

In this paper, we present the results of an experimental study on the phase behavior of well-characterized binary mixtures which represent the more complex mixtures that arise in SCF extractions of petroleum residua and coal liquids. These binary mixtures consist of pentane and toluene with meso-tetraphenylporphyrin (TPP). Porphyrins occur naturally in crude oils (11,12) and represent an important class of high molecular-weight constituents of these oils, including those which contain heavy metals, such as nickel and vanadium. 

AAA-alumina (75% Si02/25% AI2O3 aluminosilicate gel provided by Davison) was used without further pretreatment. Benzene solutions of either vanadyl porphyrin (5, 10, 15, 20-tetraphenyl-21H, 23H-porphine vanadium oxide) or vanadyl naphthenate were impregnated by incipient wetness onto the EuY or the gel to generate a loading of 1.0 wt % vanadium. Vanadyl naphthenate has been widely utilized as a model V-contaminant and metalloporphyrins have been identified as metallic species in crude oil (29-30). The solvent was removed under... 

The uppgrading of heavy oil will continue to increase in importance as changes In crude oil availability causes a shift toward heavier crudes. Usually, for extra heavy crudes, the bottom resid fractions as well as its deasphalted oils may contain significant quantities of metals (i.e. nickel and vanadium). These pose a serious problem for refiners because metal contaminants accumulate on catalyst during hydroprocessing causing permanent deactivation. The use of HDM catalysts to protect downstream HDS catalysts is recommended. 

The presence of this and other materials presents potential problems in industrial processing, and there is great interest in characterization of the chemical nature of the vanadium species present. EPR is most widely used in these studies since the metal is in the oxo-vanadium(IV) state. Optical spectroscopy in the visible region can also be used on extracts since oxo-vanadium(IV) porphyrins, which absorb at around 572 nm and 534 nm 116,119), can readily be detected. However, it has been shown (120-122) that the total amount of vanadium present in crude oils and tar sand bitumen is higher than can be accounted for by the presence of oxo-vanadium(IV) porphyrins. It has therefore been suggested that the vanadyl may be bound to a range of different tetra-dentate ligands in crude oils (120-123). 

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-... 

Lewan M. D. (1984) Factors controlling the proportionality of vanadium to nickel in crude oils. Geochim. Cosmochim. Acta 48, 2231-2238. 

The detection of vanadium, nickel, and porphyrins in crude oils were analyzed by high-temperature gas chromatography-atomic emission spectroscopy (HT-GC-AES), presenting characteristic metal distribu-... 

Calcium is not as harmful and may even serve to inhibit the corrosive action of vanadium. However, the presence of calcium can lead to deposits that are not self-spalling when the gas turbine is shut down and not readily removed by water washing of the turbine. Lead can cause corrosion, and, in addition, it can spoil the beneficial inhibiting effect of magnesium additives on vanadium corrosion. Because lead is only found rarely in significant quantities in crude oils, its presence in the fuel oil is primarily the result of contamination during processing or transportation. 

Catalyst — A substance added to a reacting system, e.g., chemical reaction, which alters the rate of the reaction without itself being consumed. Most catalysts are used to increase the rate of a reaction. For example, the metal vanadium is often present in trace amounts in crude oils and acts as a catalyst to accelerate the rate of chemical oxidation of certain hydrocarbons as the oil weathers. Catalysts, such as silica and alumina, are also used during the refining of petroleum to increase the rate at which large hydrocarbon molecules are split into smaller ones, a process referred to as catalytic cracking. 

Crude oils — Petroleum in its natural form before it is subjected to any refining process such as fractional distillation or catalytic cracking. The main elements in crude oils are hydrogen and carbon as they are composed of mixtures of hydrocarbon compounds. Crude oils also contain varying amounts of sulphur, nitrogen, oxygen, and sometimes mineral salts, as well as trace metals such as nickel, vanadium, and chromium. 

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