Nickel alumina supported

Piao, L. et al., Methane decomposition to carbon nanotubes and hydrogen on an alumina supported nickel aerogel catalyst, Catal. Today, 74,145, 2002. 

Another large class of chemicals produced starting from ethanol are ethyl-amines. When heated to 150-220 °C over a silica- or alumina-supported nickel catalyst, ethanol and ammonia react to produce ethylamine. Further reaction leads to diethylamine and triethylamine. The ethylamines find use in the synthesis of pharmaceuticals, agricultural chemicals, and surfactants. 

The first example of the use of metal carbonyls to prepare supported metal particles was reported by Parkyns, who prepared an alumina-supported nickel catalyst from Ni(CO)4 [3]. Since then, many studies of the groups of Professors Yermakov, Ugo, Basset, Ichikawa, Guczi and Gates, among others, have constituted the bases for knowledge in this field [4-10]. 

Hydrogenation of Cgg on alumina-supported nickel leads selectively to CggHgg [72], Degradation products or other hydrofullerenes such as CggHjg or CggH44 were not observed. The reduction was carried out in toluene in an autoclave at 50-250 °C with the hydrogen pressure ranging from 2.5 to 7.5 MPa for 1 to 24 h. 

There have been a considerable number of papers reporting the properties of sulphur-resistant methanation catalysts, i.e., catalysts which can operate successfully in significant partial pressures of H2S. Most of these report work using catalysts containing vanadium, molybdenum, and such metals. However, attempts have been made to find nickel-based catalysts containing suitable additives to allow them to operate in such atmospheres. For example, Bartholomew and Uken115 have compared the deactivation behaviour of a range of nickel catalysts in 10 p.p.m. H2S. They found that nickel boride catalysts and Raney nickel materials deactivated more slowly than did unsupported nickel and alumina-supported nickel. They attributed this improvement to two factors ... 

Alumina-supported nickel catalysts are an excellent example for the advantages of and the problems associated with coprecipitation processes for the manufacture of catalysts. Such catalysts are accessible via several pathways, as impregnation, deposition/precip-itation, coprecipitation from alumina gels, and more conventional coprecipitation routes. Also, for coprecipitation, different routes are possible, the first examples originating from the 1920s [48]. Starting from the nitrate solutions of nickel and aluminum, there are at least three different routes ... 

The temperature of calcination of a support before impregnation understandably modifies the interaction between the precursor and the support, as shown in the above case and that of alumina-supported nickel catalysts [68]. 

Comparison of Methanation Activities for Zeolite and Alumina Supported Nickel Catalysts... 

Platinum, ruthenium, and mixed platinum-ruthenium species supported on silica Various alumina-supported nickel complexes Dispersion of metallic species during treatments in 02 and H2 at temperatures up to 473 K Reaction of nickel complexes and interaction with support at temperatures... 

Molina, R., M. A. Centeno, and G. Poncelet, a-Alumina-Supported Nickel Catalysts Prepared with Nickel Acetylacetonate. 1. Adsorption in the Liquid Phase , J. Phys. Chem. B. 1999,103, 6036-46. 

A Ni-As(B) catalyst prepared by the borohydride reduction of alumina-supported nickel arsenate gave, on hydrogenation of 1-bromo-l 1-hexadecyne (13) in the presence of a small amount of acetone, a 97% yield of the alkene (14) having a 92 5 cis/trans ratio. No hydrogenolysis of the carbon-bromine bond occurred. "> 2 Borohydride reduction of cobalt acetate gave a Co(B) catalyst that was somewhat less active than Ni(B) but that was quite selective in alkyne semihydrogenations (Eqn. 16.20). ... 

Chemisorption uptakes of Hj at 298-303 K for alumina supported nickel catalysts were measured. The corresponding nickel surface areas were calculated and subsequently sulfur contents at saturation were determined. The average values were of the same magnitude as the amounts of sulfur that were not desorbed from the catalysts during the TPH treatments. Hence, it may be concluded that the saturation layer of sulfor remains on the catalyst even after regeneration in hydrogen atmosphere. 

Hgtirc 2.6. Surface area for alumina-supported nickel catalysts. "... 

Based on the experimental infoimation we can conclude that the main routes for the hydrogenation of citral over alumina supported nickel goes through citronellal to citronellol and finally to 3,7-dimethyloctanol, whereas the contribution of nerol and geraniol to the hydrogenation path is of very minor importance. The hydrogenation kinetics was described with first order rate laws with respect to the substrate molecules [2],... 

The nature of the carbon deposits formed on an alumina-supported nickel catalyst have been characterized by their reactivity with H2 and H 0 during temperature-programmed surface reaction (TPSR). 

Carbon Deposited on Nickel via 02 Exposure TPSR with 1-atm H2 Carbon deposited on alumina-supported nickel (17 wt%) following ethylene exposure at various temperatures has a wide range of activity for reaction with H2 (Figure 2). Different states of carbon are identified by maxima in the rate of CH production. The temperature of the rate maximum (T ) for a particular carbon state was generally found to he independent of both the amount of carbon in that state and the temperature of deposition. Thus T will be taken as characteristic of the reactive state of... 

The TPSR 0 ) results did not differ significnatly for either of the alumina-supported nickel catalysts as seen by T for the various carbon states (Table II). This was true for both TPSR (H2) with 1-atm Ha and TPSR (H2O) with 0.03-atm 0 in He. 

POPULATION OF TPSR STATES FOR CARBON DEPOSITED ON AN ALUMINA-SUPPORTED NICKEL CATALYST (G-56H) FOLLOWING ETHYLENE EXPOSURE... 

Alumina supported nickel, cobalt and iron catalysts containing 10, 30 and 50 wt % of metal were prepared by co-precipitation method at constant pH conditions (pH = 8 for Ni and Co and pH = 7 for Fe) as described earlier [7], Hydrogen and oxygen adsorption measurements were carried out over the catalysts using a conventional high vacuum system according to the procedure described elsewhere [7]. BET surface area was measured... 

Arsenic, normally considered a notorious catalyst poison, actually promoted the selectivity of 1-bromo-ll-hexadecyne hydrogenation over a catalyst formed by the action of borohydride on alumina-supported nickel arsenate [18] ... 

Although palladium occupies the dominant position in semi-hydrogenation catalysts, it is by no means the only metal suitable for formulation into a viable catalyst. Mention has already been made of the nickel boride alternatives, with or without copper promotion, for example. Other examples include the skeletal catalyst Raney nickel [69], alumina-supported nickel [70], and aluminum phosphate-supported nickel [71] (Eqs 21 and 22) ... 

Catalyst development and catalyst/ microreactor integration. Several ATR, WGS, and PrOx catalysts have been prepared. The ATR catalysts include beta-alumina supported nickel. These catalysts are being evaluated. Transition metal carbide and oxide supported gold catalysts were demonstrated to be highly active for the WGS... 

Table 1 summarizes the denomination and the characterization data of the prepared egg-shell catalysts, as well as a conventional alumina supported nickel oxide catalyst C7 characterized earlier [24] that is used for comparison of the catalytic performances. 

Table 1. Denotnination and characteristic data of the egg-shell catalysts and the alumina supported nickel oxide catalyst N1O/AI2O3...

Surface-science studies using nickel single-crystal surfaces revealed that the methanation reaction is surface-structure-insensitive. Both the (111) and (100) crystal faces yield the same reaction rates over a wide temperature range. These specific rates are also the same as those found for alumina-supported nickel, further proving the structure insensitivity of the process. This is also the case for the reaction over ruthenium, rhodium, molybdenum, and iron. 

Catalysts surface poisoning by arsenic Mechanism of triphenylarsine interaction with alumina supported nickel. 

Hydrogenolysis of triphenylarsine (AsPh ) on alumina supported nickel (Ni/Al Oj) has been studied as model reaction for metallic catalyst poisoning. The hydrogenolysis of AsPh on Ni/Al Oj occurs at temperature ranging from 303 to 443 K under 12 bars of hydrogen and in n-heptane solution. It has been followed by kinetics analysis of the AsPh consumption and Benzene and cylohexane evolution as well as XRD measurements of the metallic and intermetallic phase(s). 

Triphenylarsine (AsPhs) hydrogenolysis on Ni/AlaOs can be used as a model for metallic poisoning by organometallic compounds. The aim of this work is to study the process of the Ni/A Oa deactivation by AsPhs in the model reaction of benzene hydrogenation and to describe the mechanism of AsPhs reaction with various alumina supported nickel solids. 

Triphenylarsine (AsPhs) and benzene were purchased from Aldrich. The n-heptane used as solvent was freshly distilled and was kept in a glass flask, under argon. Alumina supported nickel were prepared by the incipient wetness procedure. The alumina surface area was measured by N2 adsorption and the metal loading was measured by elemental analysis. 

Three alumina supported nickel samples were prepared with nickel loading ranging from 8 to 25% and dispersion varying from 10 to 28%. The surface area and the pore size of the support, the metal loading, the dispersion of the samples, deduced from hydrogen chemisorption and from magnetization curves are reported in Table 1. 

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