Nickel sulfide catalysts

Ahlborn Wheeler Nickel Sulfide Catalysts William J. Kirkpatrick... 

Another dehydrogenation process was introduced before 1944 for converting methyl-cyclohexane to toluene over a tungsten-nickel sulfide catalyst. Substantially higher hydrogen partial pressures are employed in this process than in hydroforming. 

Vladimir Haensel Chemical Characteristics and Structure of Cracking Catalysts A. G. Oblad, T. H. Milliken, Jr., and G. A. Mills Reaction Rates and Selectivity in Catalyst Pores Ahlborn Wheeler Nickel Sulfide Catalysts William J. Kirkpatrick... 

The catalytic gas-phase hydrogenation processes for nitrobenzene can be carried out using a fixed-bed or a fluidized bed reactor. Bayer and Allied work with nickel sulfide catalysts at 300°C to 475°C in a fixed bed. The selectivity to aniline is more than 99%. The catalytic activity slowly decreases due to carbon... 

The reaction occurs at 150-200° and about 140 atm in the presence of cobalt sulfide or nickel sulfide catalysts, yields averaging 70%. 

Nickel sulfide catalysts, 3, 329 Noble metal, synthetic polymer catalysts, and mechanism of action, 6, 125... 

The presence of sulfur, combined or elementary, has a great influence on the course of a reaction carried out over nickel catalysts. A reaction which either proceeds at a greater rate or more selectively over nickel catalysts in the presence of sulfur is said to be promoted and a reaction which is retarded or which proceeds less selectively is said to be poisoned. It is convenient to speak of these sulfurized nickel catalysts collectively as nickel sulfide catalysts. 

In some systems in which nickel sulfide catalysts are used, the nickel is initially introduced into the catalytic reactor either in the form of the metal or of the oxide. The equilibrium between nickel and sulfur-containing reactants (H S, CSz, etc.) is established in a short time, so that the resulting nickel sulfide corresponds to the solid phase which is in equilibrium with the reacting components at the temperature and partial Contribution from The International Nickel Company Fellowship, Mellon Institute, Pittsburgh, Pa. 

Since nickel sulfide catalysts are often used in systems containing hydrogen, it is necessary to consider the equilibrium between hydrogen and nickel sulfide. Badger, Grifiith, and Newling (4) examined the equilibrium... 

Nickel sulfide catalysts may be prepared by any of the following reactions ... 

The Ni3S2 catalyst on china clay used for the catalytic removal of organic sulfur compounds from coal gas has an average life of three months (8). Nickel sulfide catalysts lose activity, as a rule, because they become coated with reaction products which are insufficiently volatile or soluble under the prevailing conditions. However, a nickel sulfide... 

The first step in regenerating the coated, inactive nickel sulfide catalysts is to remove the reactants and products of the catalytic reaction aloi with the extraneous material coating the catalyst. In most cases, extraction of the catalytic mass with solvents, or purging with steam is adequate for this clean-up. The more resistant film of coke or tar is then removed by oxidation with air under carefully controlled conditions to avoid over-heating the catalyst. During this oxidation, the nickel sulfide is usually oxidized to NiO. This NiO is then reduced and sulfided in the same manner as in the initial preparation of the catalyst. 

Nickel sulfide catalysts are used in the hydrogenation of organic sulfur compounds because, in most cases, metallic catalysts react with, and are poisoned by, organic sulfur compounds. Most of these hydrogenations are carried out at temperatures above 100°. 

Sulfur may be substituted for hydrogen in the reduction of saturated hydrocarbons over nickel sulfide catalysts. In this way, carbon disulfide may be synthesized from methane plus hydrogen sulfide over nickel sulfide catalysts at 450-750°. The same reaction takes place with other hydrocarbons at slightly lower temperatures. At still lower temperatures, hydrogen sulfide adds to the double bonds of olefins in the presence of nickel sulfide, and of nickel sulfide-chromium sulfide mixtures, to yield thiols. 

Sulfur or the thiol group may be substituted for functional groups as well as for hydrogen in the presence of nickel sulfide catalysts. Simultaneous replacement of oxygen by sulfur in carbonyl compounds and hydrogenation to thiols may be carried put over nickel sulfide catalysts. 

Reduction of Nitriles and of Nitro Compounds to Amines Nitro compounds can be reduced over metallic catalysts at relatively low temperatures and pressures. However, for several reasons, it is more desirable to carry out this reduction over nickel sulfide catalysts. The feedstock does not have to be freed of sulfur compounds. A high hydrogen pressure can be used, which makes continuously operating units more eflicient and favors the formation of primary amines which are usually the desired products. 

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