Vanadium and nickel

Physical methods of fractionation of tar sand bitumen usually indicate high proportions of nonvolatile asphaltenes and resins, even in amounts up to 50% wt/wt (or higher) of the bitumen. In addition, the presence of ash-forming metallic constituents, including such organometaUic compounds as those of vanadium and nickel, is also a distinguishing feature of bitumen. 

Generally, most asphalts are 79—88 wt % C, 7—13 wt % H, trace-8 wt % S, 2—8 wt % O, and trace-3 wt % N (Table 7). Trace metals such as iron, nickel, vanadium, calcium, titanium, magnesium, sodium, cobalt, copper, tin, and 2inc, occur in cmde oils. Vanadium and nickel are bound in organic complexes and, by virtue of the concentration (distillation) process by which asphalt is manufactured, are also found in asphalt. 

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. 

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. 

Vanadium and nickel are poisons to many catalysts and should be reduced to very low levels. Most of the vanadium and nickel compounds are concentrated in the heavy residues. Solvent extraction processes are used to reduce the concentration of heavy metals in petroleum residues. 

An additional mechanism affects the deposits formation from the H-Oil reactor, rejection of vanadium and nickel sulfides from the catalyst. In the vacuum tower, asphaltene precipitation was found to be the prevalent fouling mechanism. In asphaltene... 

As the world s known crude oil reserves diminish, we are confronted with the prospect of treating progressively less desirable crude oils. These materials contain high levels (typically several percent) of organic sulfur and nitrogen, as well as organically complexed vanadium and nickel at the level of... 

For regeneration to be technically viable, it must be able to remove deposited vanadium and nickel quantitatively as well as the carbonaceous coke which was co-deposited. The catalyti-cally active metals should remain unaffected in amount, chemistry, and state of dispersion. The alumina support should remain intact, with the surface area, pore-size distribution and crush strength after treatment comparable to that of the original. To be economically viable, the process should be accomplished in a minimum of steps at nearly ambient temperatures and preferably in aqueous solution. The ultimate proof of any such scheme is for the catalytic activity of the regenerated catalyst to be equal to that of a fresh one. 

Baker, E. W., 1964, Vanadium and nickel in crude petroleum of South America and Middle East Origin Journal of Chemistry and Engineering News, Vol. 42, No. 15, pp. 307-308. 

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

Fig. 14.7 Extraction of vanadium and nickel from soot and flue ash.

All oxidation reactions are coupled to reduction reactions. In many cases redox reactions can also involve or be affected by changes in the surrounding environment, such as changes in the pH or temperature (i.e., endothermic or exothermic reactions). Many elements in the subsurface can exist in various oxidation states, some examples include elements like carbon, nitrogen, oxygen, sulfur, iron, cobalt, vanadium, and nickel. 

Recently, it has been reported in the patent literature that vanadium (and nickel) resistance in a FCC can be significantly enhanced by the addition of certain diluents capable of acting as metal scavengers (1-4). In fact, addition of alumina and... 

Under FCCU operating conditions, almost 100% of the metal contaminants in the feed (such as nickel, vanadium, iron and copper porphyrins) are decomposed and deposited on the catalyst (2). The most harmful of these contaminants are vanadium and nickel. The deleterious effect of the deposited vanadium on catalyst performance and the manner in which vanadium is deposited on the cracking catalyst differ from those of nickel. The effect of vanadium on the catalyst performance is primarily a decrease in catalyst activity while the major effect of nickel is a selectivity change reflected in increased coke and gas yields (3). Recent laboratory studies (3-6) show that nickel distributes homogeneously over the catalyst surface while vanadium preferentially deposits on and reacts destructively with the zeolite. A mechanism for vanadium poisoning involving volatile vanadic acid as the... 

Residual oil combustion impact served as a test of the model s ability to predict point source emissions. Since vanadium and nickel emissions in Portland are almost totally associated with residual oil use, the CMB method was able to assign impacts with a high degree of confidence by using these two elements as chemical tracers. 

Nickel.—Vanadium and nickel are miscible in all proportions in the liquid state up to 36 per cent, vanadium. The solid alloys, which contain up to 20 per cent, vanadium, appear to be homogeneous, but those richer in vanadium consist of two kinds of crystals.10 These alloys are made by reducing a mixture of vanadium pentoxide and nickel oxide.u... 

Vanadium and nickel are present in parts-per-million quantities in most crude oils, usually in large, oil-soluble organometallic compounds termed porphyrins. The chemical structure of porphyrins is closely akin to the coloring matter in blood and to chlorophyll in plants. 

---