Nickel molybdenum/aluminum catalyst

The predominant process for manufacture of aniline is the catalytic reduction of nitroben2ene [98-95-3] ixh. hydrogen. The reduction is carried out in the vapor phase (50—55) or Hquid phase (56—60). A fixed-bed reactor is commonly used for the vapor-phase process and the reactor is operated under pressure. A number of catalysts have been cited and include copper, copper on siHca, copper oxide, sulfides of nickel, molybdenum, tungsten, and palladium—vanadium on alumina or Htbium—aluminum spinels. Catalysts cited for the Hquid-phase processes include nickel, copper or cobalt supported on a suitable inert carrier, and palladium or platinum or their mixtures supported on carbon. 

The reaction scheme is rather complex also in the case of the oxidation of o-xylene (41a, 87a), of the oxidative dehydrogenation of n-butenes over bismuth-molybdenum catalyst (87b), or of ethylbenzene on aluminum oxide catalysts (87c), in the hydrogenolysis of glucose (87d) over Ni-kieselguhr or of n-butane on a nickel on silica catalyst (87e), and in the hydrogenation of succinimide in isopropyl alcohol on Ni-Al2Oa catalyst (87f) or of acetophenone on Rh-Al203 catalyst (87g). Decomposition of n-and sec-butyl acetates on synthetic zeolites accompanied by the isomerization of the formed butenes has also been the subject of a kinetic study (87h). 

Alloys are prepared commercially and in the laboratory by melting the active metal and aluminum in a crucible and quenching the resultant melt which is then crushed and screened to the particle size range required for a particular application. The alloy composition is very important as different phases leach quite differently leading to markedly different porosities and crystallite sizes of the active metal. Mondolfo [14] provides an excellent compilation of the binary and ternary phase diagrams for aluminum alloys including those used for the preparation of skeletal metal catalysts. Alloys of a number of compositions are available commercially for activation in the laboratory or plant. They include alloys of aluminum with nickel, copper, cobalt, chromium-nickel, molybdenum-nickel, cobalt-nickel, and iron-nickel. 

The preparation of the Raney-Ni catalysts follows the conventional method [14], Pure metallic cobalt, chromium, iron, and molybdenum as fine powders were added to nickel and aluminum powders, with a Ni/Me molar ratio around 0.02. Then, the alloy powders were submitted to a leaching process with soda under different temperatures to obtain promoted Raney-Ni catalysts. Besides the prepared samples, a commercial Raney-Ni catalyst (GETEC) was also tested [15], The industrial leaching process from GETEC was adopted sodium hydroxide solution (6 M) was added to the alloy and the mixture was heated at 100 and 120 °C for 2 h and stirred at 1200 rpm. 

Hydrotreating also produces some residuals in the form of spent catalyst fines, usually consisting of aluminum silicate and some metals (e.g., cobalt, molybdenum, nickel, tungsten). Spent hydrotreating catalyst is now listed as a hazardous waste (K171) (except for most support material). Hazardous constituents of this waste include benzene and arsenia (arsenic oxide, AS2O3). The support material for these catalysts is usually an inert ceramic (e.g., alumina, AI2O3). 

These heterogeneous catalysis contain nickel, cobalt, molybdenum, tungsten, platinum, or palladium on acidic aluminum silicate or zeolite supports. As with reforming catalysts, the catalysts here are also believed to be... 

Following the development of sponge-metal nickel catalysts by alkali leaching of Ni-Al alloys by Raney, other alloy systems were considered. These include iron [4], cobalt [5], copper [6], platinum [7], ruthenium [8], and palladium [9]. Small amounts of a third metal such as chromium [10], molybdenum [11], or zinc [12] have been added to the binary alloy to promote catalyst activity. The two most common skeletal metal catalysts currently in use are nickel and copper in unpromoted or promoted forms. Skeletal copper is less active and more selective than skeletal nickel in hydrogenation reactions. It also finds use in the selective hydrolysis of nitriles [13]. This chapter is therefore mainly concerned with the preparation, properties and applications of promoted and unpromoted skeletal nickel and skeletal copper catalysts which are produced by the selective leaching of aluminum from binary or ternary alloys. 

Paul (17) has described nickel catalysts of the Raney type which were prepared from alloys of nickel, aluminum and cobalt, or chromium, or molybdenum. The alloy contained 52% aluminum to 48% of the other two metals. 

To identify the phosphorus-containing compounds described in the previous sections and the related species containing aluminum, molybdenum, cobalt, or nickel which might be present in hydrotreating catalysts, it is convenient to use techniques such as NMR, IR, UV. and Raman spectroscopies and XRD. XRD is useful for characterizing crystalline bulk compounds, and other techniques are appropriate for well-dispersed species and amorphous phases. Typical IR, Raman, and NMR data presented in Tables VI, VII, and VIII, respectively, could be the basis for such identifications. 

Abbattista et al. (26) found that phosphorus addition prevents crystallization of the y-alumina phase and the transformation from y- to a-alumina in the system AI2O3 —AIPO4 (Fig. 23). More precisely, Morterra et al. (77) reported that phosphates do not affect the phase transition from low-temperature spinel alumina (y-alumina) to high-temperature spinel aluminas 8 and 6 phases) but delay the transition of 8 and 9 to a-alumina (corundum). Stanislaus et al 46) also reported that phosphorus significantly improves the thermal stabihty of the y-alumina phase in P/Al catalysts. However, the same authors found that the positive effect of phosphorus seems to be canceled in the presence of molybdenum due to the formation of aluminum molybdate. Thermal treatments of MoP/Al catalysts at temperatures >700°C result in a considerable reduction of SSA and mechanical strength. The presence of phosphorus does not prevent the reaction between the molybdenum oxo-species and alumina since the interaction between molybdates and phosphates is weak. The presence of nickel does not obviously affect the positive effect of phosphorus in terms of thermal stability 46). On the other hand, Hopkins and Meyers 78) reported that the thermal stability of commercial CoMo/Al and NiMo/Al catalysts is improved by the addition of phosphorus. 

X-Ray. X-ray analysis data, summarized in Table 1, shows that the deposit contains 20.8 % nickel (Ni) plus vanadium(V), and 8.8 % sulfur (S). Interestingly, the data reveals only 2.5% of each of the primary catalyst components aluminum (Al) and molybdenum (Mo) hence, it is unlikely that carryover of the catalyst contributes significantly to the accumulation of V and Ni. Furthermore, it appears unlikely that major amounts of V and Ni derive from the reactor metallurgy, as the deposit contains only 1.7% iron (Fe). The rejection of "vanadium-and nickel-sulfide"[5] from the catalyst surface may account for the high amounts of V, Ni, and S. 

Recent patent disclosures by the Standard Oil Co. of Indiana indicate that their process for the polymerization of ethylene is also a relatively low-pressure process, and the following process information is based on these disclosures. The polymerization process is a fixed-bed process employing a prereduced catalyst, ethylene pressures of 809-1,000 psi, and temperatures somewhat greater than 200°C. The metal oxides (such as nickel, cobalt, and molybdenum) can be supported on either charcoal or alumina, and materials such as lithium aluminum hydride, boron, alkali metals, and alkaline-earth hydrides may be used as promotors. Variations of this process are reported to produce polyethylene resins with densities from 0.94-0.97. 

The cell system is sensitive to trace quantities of catalysts in the brine, for example, vanadium, molybdenum, and chromium at the 0.01-0.1 ppm level or iron, cobalt, nickel, and tungsten at the parts per million level. Magnesium, calcium, aluminum, and barium are also active at the parts per million level. 

Valverde, I.M., Paulino, J.F., Afonso, J.C. 2008. HydrometaUurgical route to recover molybdenum, nickel, cobalt and aluminum from spent hydrotreating catalysts in sulphuric acid medium. J. Hazard. Mater. 160 310-317. 

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