Vanadium contaminants

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... 

Occelli, M. L. Stencel, J. M. "Surface-Metals Interaction in Fluid Cracking Catalysts During the Upgrading of Vanadium-Contaminated Gas Oils," in Proceedings of the International Zeolite Conference. Wurzburg, Germany, September 1988. 

Vanadium-Contaminated Aluminas and Aluminosilicate Gels 51V NMR Spectroscopic Characterization... 

Vanadium contamination has higher effect on conversion of residue feed... 

Tin Passivation of Vanadium Contaminants in Model Fluid Cracking Catalysts... 

X-ray powder diffraction results have shown that addition of tetraphenyl tin to the vanadium contaminated zeolite or to the zeolite-gel mixture leads to significantly more retention of... 

LDG segregation of catalyst by vanadium level has been studied extensively. A test performed on a nickel-molybdenum catalyst is summarized in Table 4. In this test case the vanadium level on the lightest fraction was less that a third of that on the heaviest fraction. Surface area and compacted bulk density correlated with the level of vanadium contamination. Most importantly, it was shown... 

Levels of Significant Exposure to Vanadium and Compounds - Inhalation 2-2 Levels of Significant Exposure To Vanadium and Compounds - Oral 2-3 Existing information on Health Effects of Vanadium and Compounds 5-1 Frequency of NPL Sites with Vanadium Contamination ... 

FIGURE 5-1. FREQUENCY OF NPL SITES WITH VANADIUM CONTAMINATION ... 

First, any residual metal contamination from the buffer and from other sources is concentrated on the column. As a result ligands in the sample that form thermodynamically stable complexes with the metals will bind to them. It is also possible that non-specific effects such as local changes in ionic strength may lead to the elution of some of the metals with the sample. In either case new species are introduced into the fractions. Furthermore, the amount of metal associated with specific ligands may be over-estimated. Experiments by Woittiez (1984) have shown that zinc, copper, manganese and vanadium contamination on a column eluate with the protein fractions. This will doubtless lead to the over-estimation of the protein-bound fraction. 

Vanadium is a frequent constituent of stack-emissions of oil-fired, power-generating stations. Juinchang et al. (1995) reported on the vanadium contamination of... 

Juinchang, R., Freedman, B., Coles, C., Zwicker, B., Holzbecker, J., Chatt, A., 1995. Vanadium contamination of lichens and tree foliage in the vicinity of three oil-tired power plants in eastern Canada. J. Air Manag. Assoc. 45,461 64. 

Naturally occurring titanium dioxide may appear red, or reddish brown to black. The color is normally due to the presence of iron, chromium, or vanadium contamination, which may amount to 10% of the total titanium content [3]. 

During electrolysis, vanadium again was extremely harmful. Concentrations less than 2 mgpl completely stopped the formation of amalgam [68]. As another example, 0.1 ppm vanadium in the brine can reduce the current efficiency by 0.7%. The fact that there are many synergistic combinations of metals puts a particular burden on the brine purification process [69]. While vanadium has pronounced effects, it is less of a practical problem now than it was at the time of the work reported here. Petrocoke was the base for the graphite used in anode manufacture and therefore the primary source of vanadium contamination. With the adoption of dimensionally stable metal anodes, vanadium contamination became a less frequent and a less serious problem. 

Larocca, M., "Fast Catalytic Cracking with Nickel and Vanadium Contaminants", Ph.D. Thesis, The University of Western Ontario, London, Ontario, Canada (1988). 

Recently, some members of a university s chemistry and engineering departments met with representatives of an oil company to discuss how the faculty and students could cooperate on industrial research. One major topic they discussed was vanadium contamination in oil, a serious problem of continuing concern. Because vanadium is toxic, the U.S. government regulates the quantity of vanadium that can be emitted by industrial processes and oil companies have to figure out environmentally acceptable ways to remove vanadium from oil. 

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