Raney nickel catalysts composition

Dry reduced nickel catalyst protected by fat is the most common catalyst for the hydrogenation of fatty acids. The composition of this type of catalyst is about 25% nickel, 25% inert carrier, and 50% soHd fat. Manufacturers of this catalyst include Calsicat (Mallinckrodt), Harshaw (Engelhard), United Catalysts (Sud Chemie), and Unichema. Other catalysts that stiH have some place in fatty acid hydrogenation are so-called wet reduced nickel catalysts (formate catalysts), Raney nickel catalysts, and precious metal catalysts, primarily palladium on carbon. The spent nickel catalysts are usually sent to a broker who seUs them for recovery of nickel value. Spent palladium catalysts are usually returned to the catalyst suppHer for credit of palladium value. 

Replacement of halides with deuterium gas in the presence of a surface catalyst is a less useful reaction, due mainly to the poor isotopic purity of the products. This reaction has been used, however, for the insertion of a deuterium atom at C-7 in various esters of 3j -hydroxy-A -steroids, since it gives less side products resulting from double bond migration. Thus, treatment of the 7a- or 7j5-bromo derivatives (206) with deuterium gas in the presence of 5% palladium-on-calcium carbonate, or Raney nickel catalyst, followed by alkaline hydrolysis, gives the corresponding 3j3-hydroxy-7( -di derivatives (207), the isotope content of which varies from 0.64 to 1.18 atoms of deuterium per mole. The isotope composition and the stereochemistry of the deuterium have not been rigorously established. 

Concurrent hydrogenation of acetone (A) and cyclohexene (B) in cyclohexane occurs with Raney nickel catalyst at 25. Catalyst concentration was 2 g/liter and the product compositions also are in g/liter. Determine the orders and relate the amounts of the reactants. 

Raney nickel catalysts, unpromoted or doped with molybdenum or chromium, were prepared from the precursor alloys of the type Ni A13. The structure and phase composition of the catalysts have been deternfmetl. Hydrogenation of valeronitri le at 90°C and 1.6 MPa in cyclohexane was performed to evaluate catalyst activities and the relative amounts of amines formed. Doping catalysts by chromium improved reaction rates and yields of primary amine, whereas molybdenum addition was ineffective. 

Table 1 Composition and characterization of Raney-nickel catalysts...

Raney nickel catalyst to yield the tooth friendly sweetener Isomalt (Siidzucker), chemically an equimolar composition of 6-o-a-D-glucopyranosido-D-sorbitol (1,6-GPS) and 1 -o-a-D-glucopyranosido-D-mannitol-dihydrate (1,1 -GPM-dihydrate)... 

Hydrogenation over Raney nickel was found to be even less stereoselective. 2-, 3- and 4-methylmethylenecyclohexenes gave different mixtures of cis and irons dimethylcyclohexanes depending not only on the structure of the starting alkene but also on the method of preparation and on the freshness of the catalysts. The composition of the stereoisomers ranged from 27-72% cis to 28-73% irons [340],... 

Microscopic and spectroscopic investigations (SEM and XPS) reveal the relatively fast change of the chemical composition of nickel sulfide coatings upon the onset of cathodic hydrogen evolution (74). Indeed, at 90°C all nickel sulfide phases are reduced to porous nickel within several days to a week s time. They lose some catalytic activity with time with an increase in overvoltage between 0.15 and 0.3 V after continuous operation for 1 year. It is clear that the catalyst after I week is already no longer nickel sulfide but some type of Raney nickel. Thus far the initial catalytic activity of the NiS, coating is of little relevance. The respective results and data are due to be published by the present authors (73). 

For hydrogen oxidation bi-component metal doped systems deposited on Raney nickel for AFC Mo and W carbides for AFC prepared by method of precipitation from a gas phase Radicals of following composition -OH, -OSO3H, -COOH, -OPO(OH)3 for PEMFC Some organic catalysts like biologically active [NiFe]-hydrogenase, pyropolymers, etc. ... 

Raney nickel electrocatalysts have also found useful applications as active electrodes for the HER (179, 180). The activity of Raney Ni catalysts is established after leaching out the base metal, Al or Zn. Choquette et al. (181) have examined the changes in morphology and composition of Raney-Ni composite catalytic electrodes accompanying dissolution of the base metal in concentrated NaOH. The depletion of Al from the Raney particles is, of course, accompanied by a major increase in real area with time of leaching and also, interestingly, with possible phase transformations (181). The electro-catalytic activity is, however, surprisingly, practically independent of time. 

Raney nickel is a sponge-like material made up of 2.5-15 nm microcrystallites that are agglomerated into macroparticles several microns in diameter. The surface area and composition of these particles depend on the base concentration and temperature used for the removal of the aluminum from the alloy. High temperature preparations that remove almost all of the aluminum generally have a surface area of 50-80 m /g. Catalysts prepared at temperatures of 50°C or lower have more aluminum present and surface areas of 100-120 m /g. These surface areas are related to the pore diameters and pore volume of the catalysts. The more extensive the base attack on the alloy the larger the average pore diameter and pore volume of these particles and the smaller their surface area. ... 

Raney, M. Process of Producing Nickel Catalysts 1961 US 2,977,327 Richardson-Merrell Pharmaceutical Compositions containing Substituted Aralkyl Amines 1967 GB 1,071,120... 

Raney-type nickel catalysts are typically prepared by leaching aluminium from a Ni-Al alloy using a concentrated sodium hydroxide solution [1-3], This process of activation critically affects the structure and properties of Raney-type nickel catalysts. The initial structure and composition of the starting alloy also influence the performance of the final catalyst [4-7], In this paper, numerical modelling is compared to experimental measurements in an attempt to simulate both the 3D morphology of as-leached Raney-Ni catalyst material and investigate the nature of the exposed catalyst surfaces. 

Nickel catalysts (b), non-Raney types. Tyman prepared a catalyst of the approximate composition Ni/Al203 by treatment of 1 1 nickel-aluminum alloy with water at 70°. Extensive washing is not required, and the catalyst is not subject to influence by a trace of alkali. 

Here, we present a computational study on Raney-Nickel [1], which is a nanostructured amorphous catalyst used in many industrial applications. It is routinely used in hydrogenation reactions such as the reduction of benzene to cyclohexane. Raney-Nickel is typically prepared by quenching a molten mixture of a NiAl alloy from which Al is leached out for producing the final catalyst The initial alloy precursor composition is important because it affects the NiAl phases formed during the quenching process. These phases have different leaching properties influencing the porosity of the catalyst and thus its performance. 

In this work, we have presented a molecular modeling smdy on Raney-Nickel. Our results show a dependence of the pore size on the initial precursor and final catalyst compositions. The simulations indicate a stabilizing influence of the aluminum on the remaining porosity. In addition, thermodynamic modeling of physical properties of a possible reactant mixture provide insights into optimal initial reaction conditions. Furthermore, we have shown results on the chemisorption of benzene on Raney-Nickel which were compared to the adsorption on a conventional clean Ni surface. 

Non-Raney Nickel typer. This includes a catalyst of the composition Ni/Al203 formed by treating Ni-7U alloy with H2O at 70 [Tyman Chem Ind 404 I964, and the commercially available Ni on sihca (with 60 wt% loading on Kieselguhr) and Ni on sihca/alumina (with 65 wt% loading). All Ni coordination compounds which have catalytic activity can come under this heading. 

Multicomponent alloys of nickel and aluminum activated by Ti, Mo are most widespread and wide by used materials for hydrogen electrodes of low temperature alkaline fuel cells. To make hydrogen electrodes skeletal nickel prepared by alkali-soluble of alloy with composition 50 %Ni -i- 47 % A1 -i-3 % Ti is used. Raney catalyst is processed by 20 % suspense of Fluoroplast F-4 D with following drying in vacuum at 50 °C that permits pyrophoric catalyst to protect against self combustion and serves hydrophobic binder to form electrodes [5]. 

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