Nickel catalysts precipitates

Uses. Nickel nitrate is an intermediate in the manufacture of nickel catalysts, especially those that are sensitive to sulfur and therefore preclude the use of the less expensive nickel sulfate. Nickel nitrate also is an intermediate in loading active mass in nickel—alkaline batteries of the sintered plate type (see Batteries, SECONDARY cells). Typically, hot nickel nitrate symp is impregnated in the porous sintered nickel positive plates. Subsequendy, the plates are soaked in potassium hydroxide solution, whereupon nickel hydroxide [12054-48-7] precipitates within the pores of the plate. 

This solution Is heated to 65°C and barium hydroxide added in quantity sufficient to make the concentration of the barium hydroxide 0.2 mol/liter. The solution is agitated and maintained at 65°C for 6 hours after the addition of the barium hydroxide. It is then cooled and neutralized to a pH of 6.8 with sulfuric acid. The precipitated barium sulfate is filtered out. A quantity of activated supported nickel catalyst containing 5 g of nickel is added. 

Unfortunately, investigations with ionic liquids containing high amounts of AlEtCl2 showed several limitations, including the reductive effect of the alkylaluminium affecting the temperature stability of the nickel catalyst. At very high alkylaluminium concentrations, precipitation of black metallic nickel was observed even at room temperature. 

Four pilot plant experiments were conducted at 300 psig and up to 475°C maximum temperature in a 3.07-in. i.d. adiabatic hot gas recycle methanation reactor. Two catalysts were used parallel plates coated with Raney nickel and precipitated nickel pellets. Pressure drop across the parallel plates was about 1/15 that across the bed of pellets. Fresh feed gas containing 75% H2 and 24% CO was fed at up to 3000/hr space velocity. CO concentrations in the product gas ranged from less than 0.1% to 4%. Best performance was achieved with the Raney-nickel-coated plates which yielded 32 mscf CHh/lb Raney nickel during 2307 hrs of operation. Carbon and iron deposition and nickel carbide formation were suspected causes of catalyst deactivation. 

In experiment HGR-13, the commercial grade precipitated nickel catalyst was in a reduced and stabilized condition when it was charged into the reactor. No special activation treatment was needed. It was, however, kept under hydrogen at all times until the temperature and pressure of the system were brought to synthesis conditions, at which time the synthesis feed gas was gradually fed into the system to start the run. 

General. The flame-sprayed Raney nickel catalyst was used in exexperiments HGR-10, HGR-12, and HGR-14, the pelleted precipitated catalyst in experiment HGR-13. Reactor conditions as a function of... 

Flame-Sprayed Raney Nickel Plates vs. Pellets of Precipitated Catalyst in a Packed Bed. Experiments HGR-13 and HGR-14 demonstrated that the performance of the plates sprayed with Raney nickel catalyst was significantly better than that of the precipitated nickel catalyst pellets. The sprayed plates yielded higher production of methane per pound of catalyst, longer catalyst life or lower rate of deactivation, lower CO concentration in the product gas, and lower pressure drop across the catalyst bed. 

The bed of parallel plates coated with Raney nickel catalyst was much more reactive than the bed of precipitated nickel. This was revealed by the generally lower CO concentration in the product gas during operation with the parallel plate bed for example, after 450 hrs stream time, it was 0.01% with the bed of sprayed Raney nickel (experiment HGR-14) and 0.05% with the bed of precipitated nickel catalyst (experiment HGR-13). 

Other precipitated nickel catalysts that were developed recently are reputedly superior to that used in experiment HGR-13. These catalysts will be evaluated in the near future as well as other forms of Raney nickel. 

Catalysts C, D, and E were prepared by the methods developed by Geus (1, 8). To this end, aerosil was suspended in a solution of Ni(N03)2, after which the nickel was precipitated (as the hydroxide) under carefully controlled conditions. 

Nickel catalysts, 77 94, 99, 109 precipitated, 77 121-122 Nickel-catalyzed dinitrotoluene hydrogenation, 25 194 Nickel chelates, 77 117 Nickel chloride hexahydrate, 77 109, 110 Nickel chromate, molecular formula, properties, and uses, 6 562t Nickel-chromium alloy 600, in galvanic series, 7 805t... 

In aqueous medium, the reduction of nickel(II) acetate with NaBFLt produces nickel boride66. This fine black precipitate, designated P-1 nickel, is a more active catalyst than Raney nickel for double-bond hydrogenations. The P-1 nickel catalyst produces less double-bond migration than standard Raney nickel, it is not pyrophoric and is more readily prepared than Raney nickel. 

Nickel catalysts are universal and are widely used not only in the laboratory but also in the industry. The supported form - nickel on kieselguhr or infusorial earth - is prepared by precipitation of nickel carbonate from a solution of nickel nitrate by sodiiun carbonate in the presence of infusorial earth and by reduction of the precipitate with hydrogen at 450° after drying at 110-120°. Such catalysts work at temperature of 100-200° and pressures of hydrogen of 100-250 atm 43. ... 

This is in contrast with the rhodium system where alkali metal salts were reported to have no effect on methanol carbonylation (19). In spite of the promotion effect of lithium the nickel catalyst is not maintained in a soluble stable complex form. Precipitation of nickel iodide is common when one of the alkali metals is the only catalyst promoter. 

The activity of the nickel catalyst is affected by major variations in carbon monoxide partial pressure. With very low carbon monoxide partial pressure, nickel precipitates as a metal powder and occasionally as nickel iodide. Stability of the catalyst is improved with higher CO partial pressure up to a point above which the catalyst activity drops linearly. The optimum level of carbon monoxide is different from one catalyst mixture to another. This behavior is characteristic of all the nickel catalyzed carbonylation reactions we studied. In the Li-P system, optimum carbon monoxide partial pressure is in the range of 700 to 800 psi (Table V). On the other hand, the optimum carbon monoxide partial pressure for the Li-Sn system is in the range of 220 to 250 psi, at 160 C, and 450 psi at 180 C (Table VI). It is presumed that the retarding effect of higher carbon monoxide partial pressure is associated with stabilizing an inactive carbonyl species. 

A mixture of 680 grams of 2-methyl-9-phenyl-2,3-dihydrol-pyridindene hydrobromide, 6,000 cc of water and about 100 grams of Raney-nickel catalyst is hydrogenated at room temperature and at about 1,000 lb pressure for a period of three hours. The catalyst is filtered. The clear filtrate is treated with a solution of 240 grams potassium thiocyanate in 400 cc of water. A heavy solid precipitates from which the supernatant liquid is decanted. 

Surface area, pore size, and pore volume are among the most fundamentally important properties in catalysis because the active sites are present or dispersed throughout the internal surface through which reactants and products are transported. The pores are usually formed by drying or calcining precipitates of hydrous oxides however, some materials possess porosity naturally, as in the case of carbons, natural zeolites, and others. Raney nickel catalysts... 

Sponge Nickel Catalyst Dissolve approximately 100 mg of sample in about 2 mL of hydrochloric acid, and dilute to about 20 mL with water. Place 5 mL of this solution into a test tube, add a few drops of bromine water, and make it slightly alkaline with ammonium hydroxide. Add 2 to 3 mL of a 1% solution of dimethylglyoxime in alcohol. An intense red color or precipitate forms. 

If a carrier is to be incorporated in the final catalyst, the original precipitation is usually carried out in the presence of a suspension of the finely divided support or, alternatively, a compound or suspension, which will eventually be converted to the support, may initially be present in solution. Thus, a soluble aluminum salt may be converted to aluminum hydroxide during precipitation and ultimately to alumina. Alternatively, a supported nickel catalyst could be prepared from a solution of nickel nitrate, containing a suspension of alumina, by precipitation of a nickel hydroxide with ammonia. 

A solution of 295 g. (1.79 moles) of m-nitroacetophenone [Org. Syntheses Coll. Vol. 2, 434 (1943)] in 1.1 1. of absolute ethanol is shaken with 1.5 tablespoons of Raney nickel catalyst [Org. Syntheses, 21, 15 (1940)] at 50° under an initial hydrogen pressure of 1950 lb. After uptake of hydrogen has ceased, the solvent is evaporated and the residue triturated with 400 ml. of a mixture of cold water and excess concentrated hydrochloric acid. The undissolved portion after filtration is treated again with hydrochloric acid. The combined insoluble portions from four reduction batches are washed with water until free from acid and dried (170 g.) and subjected to reduction as before. The combined hydrochloric acid solutions are treated with solid sodium carbonate with stirring until the solution is alkaline, and the precipitated m-aminoacetophenone is removed by filtration. 

A solution of 5 g. (0.027 mole) of 8-nitrolepidine (p. 226) in 100 ml. of ethanol at 75° is shaken with hydrogen [Org. Syntheses Coll. Vol. 1, 66 (1941)] at 45 lb. pressure in the presence of Raney nickel catalyst [Org. Syntheses, 21, 15 (1940)]. After absorption of hydrogen is complete, the solution is filtered to remove catalyst and the filtrate is evaporated and diluted with water. The precipitated product is recrystallized from benzene to give 3.5 g. (83 )) of 8-amino-lepidine, m.p. 84°. 1... 

The nickel catalyst (about 50 wt% nickel on kieselguhr) was prepared by an ordinary precipitation method. Sodium carbonate solution was added to a slurry of kieselguhr and nickel nitrate solution at 70 °C and precipitate was obtained. This precipitate was washed with water thoroughly and then was dried at 105 C for 12 hrs, crushed to 60-150 mesh, calcined at 350 C for 4 hrs. This was activated with 100% hydrogen at 200, 300 and 350 "C for 4 hrs. These prepared catalysts were stored in nitrogen atmospheric bottle and desiccator. 

The more ethanol in the reduction solvent, the greater the amount of BOj found in the resulting nickel boride precipitate.This ion is formed by the hydrolysis of borohydride but, since it is not very soluble in ethanol, it is not kept in solution in alcoholic solvents. The BO2 is apparently responsible for the decreased activity and increased selectivity of the P-2 nickel boride. 3,35 Vvt]ien the P-2 catalyst was isolated and washed with water before use, the resulting P-2W catalyst was more active than both the P-2 and P-1 nickel borides but it became less selective in alkene hydrogenation than the P-2 catalyst. ... 

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