Nickel activity

When nickel hydroxide is oxidized at the nickel electrode in alkaline storage batteries the black trivalent gelatinous nickel hydroxide oxide [12026-04-9], Ni(0H)0, is formed. In nickel battery technology, nickel hydroxide oxide is known as the nickel active mass (see Batteries, secondary cells). Nickel hydroxide nitrate [56171-41-6], Ni(0H)N02, and nickel chloride hydroxide [25965-88-2], NiCl(OH), are frequently mentioned as intermediates for the production of nickel powder in aqueous solution. The binding energies for these compounds have been studied (55). 

Muntz Metal Naval brass Nickel (active)... 

The neutron dose to graphite due to irradiation is commonly reported as a time integrated flux of neutrons per unit area (or fluence) referenced to a particular neutron energy. Neutron energies greater that 50 keV, 0.1 MeV, 0.18 MeV, and 1 MeV were adopted in the past and can be readily foimd in the literature. In the U.K., irradiation data are frequently reported in fluences referenced to a standard flux spectrum at a particular point in the DIDO reactor, for which the displacement rate was measured by the nickel activation [ Ni(np) t o] reaction [equivalent DIDO nickel (EDN)]. Early on, neutron irradiation doses to the graphite moderator were reported in terms of the bum-up (energy extracted) from imit mass of the adjacent nuclear fuel, i.e., MW days per adjacent tonne of fuel, or MWd/Ate. 

The HVCH ratio is an indicator of dehydrogenation reactions. However, the ratio is sensitive to the reactor temperature and the type of catalyst. A better indicator of nickel activity is the volume of... 

Approximately 60 g of Raney nickel activated catalyst (supplied as a 50% slurry in water, pH 10 by Aldrich Chemical Company) was washed twice with ethanol (150 ml) and added to a solution of 15.9 g of V in 500 ml of ethanol. The mixture was stirred at room temperature for two hours. An additional 18 g of Raney nickel was added, and the mixture was stirred at room temperature for three hours. Following workup, 9.11 g (83.4%) of crude ethyl 2,6,6-trimethylcyclohex-2-ene-l-carboxylate (VII) sufficiently pure for the next step was obtained. 

Admiralty brass (Cu 71 per cent, Zn 28 per cent, Sn 1 per cent) Nickel (active)... 

Wu B. and White R. E., Modeling of a Nickel-Hydrogen Cell. Phase Reactions in Nickel Active Material. J. Electrochem Soc. 2001 148 A595-609. 

The most recent strategy to prepare [3]radialenes is the treatment of 1,1-dihaloalkenes with activated nickel. Thus, the aryl-substituted [3]radialenes (Z,E,E)-30 and (E,E,E) 30, 27 and 32 were obtained together with the corresponding butatrienes (29, 28, 31) from the 1,1-dibromo- or 1,1-dichloroalkenes with the help of nickel activated by ultrasound (Scheme 4)11. It is worth mentioning that the mixed-substituted radialene 33 was produced, when the nickel carbenoid derived from 9-(dichloromethylene)xanthene was generated in the presence of butatriene 2811. 

It was found that a nickel-activated carbon catalyst was effective for vapor phase carbonylation of dimethyl ether and methyl acetate under pressurized conditions in the presence of an iodide promoter. Methyl acetate was formed from dimethyl ether with a yield of 34% and a selectivity of 80% at 250 C and 40 atm, while acetic anhydride was synthesized from methyl acetate with a yield of 12% and a selectivity of 64% at 250 C and 51 atm. In both reactions, high pressure and high CO partial pressure favored the formation of the desired product. In spite of the reaction occurring under water-free conditions, a fairly large amount of acetic acid was formed in the carbonylation of methyl acetate. The route of acetic acid formation is discussed. A molybdenum-activated carbon catalyst was found to catalyze the carbonylation of dimethyl ether and methyl acetate. 

Figure 6 shows the TPR spectra of adsorbed CO on nickel. The CO was desorbed mostly as the molecular form, whereas the amounts of desorbed carbon dioxide and methane were quite small. Thus, most of the CO adsorbed on nickel is in an undissociated state, and the extent of its adsorption is fairly weak, as the desorption is completed below 200 C. In contrast, the adsorption of methyl acetate on nickel is stronger than those of other reactants or products, as evaluated from the retention time in the nickel-activated carbon column shown in Table III. This fact suggests that most of the nickel is covered by methyl acetate and reaction products, and the coverage of adsorbed CO is quite low under the reaction conditions when the partial pressure of CO is close to that of methyl acetate. The carbonylation is therefore accelerated by increasing the CO/AcOMe ratio which increases the coverage of CO adsorbed competitively with methyl acetate. 

Table IV shows the reactivities of raw materials and products on a nickel-activated carbon catalyst and the effect of hydrogen on the reactions. When carbon monoxide and hydrogen were introduced into the catalyst, no product was formed. Thus, the hydrogenation of CO does not proceed at all. When methyl iodide was added to the above-mentioned feed, 43% of the methyl iodide was converted to methane. In the presence of methyl iodide small amounts of methane, methanol, and acetic acid were formed from methyl acetate, while small amounts of methane and acetic acid were also formed from acetic anhydride. Hydrogen fed with methyl acetate accelerated the formation of methane and acetic acid remarkably.

Table III. Relative Retention Time of Reactant and Product Materials on 2.5 wt% Nickel-Activated Carbon ...

Table V shows the results obtained for the carbonylation of dimethyl ether and methyl acetate with molybdenum catalysts supported on various carrier materials. In the case of dimethyl ether carbonylation, molybdenum-activated carbon catalyst gave methyl acetate with an yield of 5.2% which was about one-third of the activity of nickel-activated carbon catalyst. Silica gel- or y-alumina-supported catalyst gave little carbonylated product. Similar results were obtained in the carbonylation of methyl acetate. The carbonylation activity occured only when molybdenum was supported on activated carbon, and it was about half the activity of nickel-activated carbon catalyst.

Table V. Carbonylation Activities of Supported Molybdenum and Nickel-Activated Carbon Catalysts ...

Rh > Ir > Ni > Pd > Co > Ru > Fe A plot of the relation between the catalytic activity and the affinity of the metals for halide ion resulted in a volcano shape. The rate determining step of the reaction was discussed on the basis of this affinity and the reaction order with respect to methyl iodide. Methanol was first carbonylated to methyl acetate directly or via dimethyl ether, then carbonylated again to acetic anhydride and finally quickly hydrolyzed to acetic acid. Overall kinetics were explored to simulate variable product profiles based on the reaction network mentioned above. Carbon monoxide was adsorbed weakly and associatively on nickel-activated-carbon catalysts. Carbon monoxide was adsorbed on nickel-y-alumina or nickel-silica gel catalysts more strongly and, in part, dissociatively,... 

Methanol carbonylation over nickel- activated carbon was shown to be a structure-insensitive reaction. 

Stability of Catalytic Activity of Nickel-Activated Carbon. In Figure 3 are shown the changes in the activity and the product selectivity of a Ni/A.C. catalyst. It is clear from the figure that the activity and the selectivity are fairly stable for several hundreds of hours. After 500 hours, the carbonylated products totaled 18,000 moles per mole of supported nickel. 

Catalyst deactivation during consecutive lactose and xylose hydrogenation batches over Mo promoted sponge nickel (Activated Metals) and Ru(5%)/C (Johnson Matthey) catalysts were studied. Deactivation over sponge nickel occurred faster than on Ru/C in both cases. Product selectivities were high (between 97 and 100%) over both catalysts. However, related to the amount of active metal on the catalyst, ruthenium had a substantially higher catalytic activity compared to nickel. 

Pocket-type cadmium electrodes are made by a procedure similar to that described for the positive electrode. Because cadmium active material is more dense Ilian nickel active material, and because cadmium has a 2+ valence, cadmium electrodes, when fabricated to equal thicknesses, have almost twice the working capacity of the nickel electrode. 

B - Contamination by heavy metals - Catalyst deactivation by Vanadium - Dehydrogenation activity of Nickel - Vanadium Catcher/Resistance - Reduction of Nickel Activity... 

A new technology of catalyst production (11) is capable of generating materials in which the nickel activity as dehydrogenation agent has been stopped by a multi-step strategy. (Table IX.)... 

Figure 11.2 shows a scheme for the radioanalytical determination of 63Ni in aquatic samples.11 The method for determining nickel activity is based on the separation of this element from other radionuclides, particularly 55Fe. To separate 63Ni, the stable dimethylglyoxime (DMG) complex (DMG)2Ni is formed in ammonia and extracted with chloroform. 

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