Effect of nickel

Two common indicators track the effects of nickel on the catalyst. These are ... 

Nickel in the feed is deposited on the surface of the catalyst, promoting undesirable dehydrogenation and condensation reactions. These nonselective reactions increase gas and coke production at the expense of gasoline and other valuable liquid products. The deleterious effects of nickel poisoning can be reduced by the use of antimony passivation. 

Hensten-Pettersen, A. and Jacobsen, N. Nickel Corrosion of Non-precious Casting Alloys and the Cytotoxic Effect of Nickel In Vitro , Journal of Bioengineering, 2, 419-425 (1978)... 

Fig. 3.36 Effect of nickel on the anodic behaviour of iron alloys in 1 N H2SO4 at 25°C. Curve 1 Fe curve 2 Fe-lONi Curve 4 Ni (after Beauchamp )...

In de-aerated 10sulphuric acid (Fig. 3.45) the active dissolution of the austenitic irons occurs at more noble potentials than that of the ferritic irons due to the ennobling effect of nickel in the matrix. This indicates that the austenitic irons should show lower rates of attack when corroding in the active state such as in dilute mineral acids. The current density maximum in the active region, i.e. the critical current density (/ ii) for the austenitic irons tends to decrease with increasing chromium and silicon content. Also the current densities in the passive region are lower for the austenitic irons... 

Fig. 3.51 Effect of nickel additions to cast iron in reducing corrosion by caustic alkalis...

Table 4.25 Bimetallic corrosion effects of nickel and nickel alloys (General guidance only other factors, including relative surface areas, often exert an important...

The effect of nickel on the activity coefficient of carbon will be neglected and the effect of chromium will be taken from the value in the liquid state. From the values quoted above, to = —4-3 at 1 600°C, and assuming that the effect of chromium is simply to change the heat of solution of carbon... 

Fig. 8.30 Effect of nickel content on the susceptibility to stress-corrosion cracking of stainless steel wires containing 18-20% chromium in a magnesium chloride solution boiling at 154°C...

Fig. 8.49 Effect of nickel content on residual ductility of austenitic stainless steels (after...

For the methanation reaction in the process of converting coal to a high Btu gas, various catalyst compositions were evaluated in order to determine the optimum type catalyst. From this study, a series of catalysts were developed for studying the effect of nickel content on catalyst activity. This series included both silica- and alumina-based catalysts, and the nickel content was varied (Table I). 

Table II. Test Conditions for Study of Effect of Nickel Content...

The catalysts were reduced with 100% H2 at 371 °C and an inlet space velocity of 1000/hr. Because of the carbon-forming potential of a dry gas recycle composition and the cost of reheating the recycle if the water produced by the methanation reaction is removed, a wet gas recycle composition was used. The catalyst loading, gas composition, and test conditions for these tests are listed in Table II, and the effects of nickel content are compared in Table III. 

The mechanism of the poisoning effect of nickel or palladium (and other metal) hydrides may be explained, generally, in terms of the electronic theory of catalysis on transition metals. Hydrogen when forming a hydride phase fills the empty energy levels in the nickel or palladium (or alloys) d band with its Is electron. In consequence the initially d transition metal transforms into an s-p metal and loses its great ability to chemisorb and properly activate catalytically the reactants involved. 

Evans, P.H., Morgan, L.G., Yano, E. and Urano, N. (1992a), Chemiluminescent detection of free radical generation by stimulated polymorphonuclear leukocytes in vitro effect of nickel compounds. In Nickel and Human Health Current Perspectives (eds. E. Nieboer and J.O. Nriagu) pp. 363-373. Wiley, New York. 

Munoz, M., Codina, J., Vicente, A., Borrego, J., and Morinigo, M., Effects of nickel and lead and a support material on the methanogenesis from sewage sludge, Lett Appl Microbiol, 23 (5), 339-342, 1996. 

In mammals, the toxicity of nickel is a function of the chemical form of nickel, dose, and route of exposure. Exposure to nickel by inhalation, injection, or cutaneous contact is more significant than oral exposure. Toxic effects of nickel to humans and laboratory mammals are documented for respiratory, cardiovascular, gastrointestinal, hematological, musculoskeletal, hepatic, renal, dermal, ocular, immunological, developmental, neurological, and reproductive systems (NAS 1975 Nielsen 1977 USEPA 1980, 1986 WHO 1991 USPHS 1993). 

Systemic effects of nickel exposure include hyperglycemia, increased levels of plasma glucagon, damage to the pancreatic islet cells, decreased body weight, reduced food and water intake, and hypothermia (NAS 1975 USEPA 1980 USPHS 1993). Acute administration of nickel salts caused prompt hyperglucagonemia and subsequent hyperinsulinemia in rats, rabbits, and guinea pigs (WHO... 

Alkahem, H.F. 1995. Effects of nickel on carbohydrate metabolism of Oreochromis niloticus. Dirasat Ser. B Pure Appl. Sci. 22B 83-88. 

Datta, A.K., S.L. North, K.S. Kasprzak. 1994. Effect of nickel (II) and tetraglycine on hydroxylation of the guanine moiety in 2 -deoxyguanosine, DNA, and nucleohistone by hydrogen peroxide. Sci. Total Environ. 148 207-216. 

Evans, J.E., M.L. Miller, A. Andringa, and L. Hastings. 1995. Behavioral, histological, and neurochemical effects of nickel (II) on the rat olfactory system. Toxicol. Appl. Pharmacol. 130 209-220. 

Ghazaly, K.S. 1992. Sublethal effects of nickel on carbohydrate metabolism, blood and mineral contents of Tilapia nilotica. Water Air Soil Pollut. 64 525-532. 

Graham, J.A., D.E. Gardner, F.J. Miller, M.J. Daniels, and D.L. Coffin. 1975. Effect of nickel chloride on primary antibody production in the spleen. Environ, Health Perspec. 12 109-113. 

Jha, B.S. and M.M. Jha. 1995. Biochemical effects of nickel chloride on the liver and gonads of the freshwater climbing perch, Anabas testudineus (Bloch). Proc. Nat. Acad. Sci. India, Sec. B. 65 39 4-6. 

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