Alumina-supported nickel catalyst

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]. 

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... 

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. 

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. "... 

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). 

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... 

Parizotto NV, Zanchet D, Rocha KO, Marques CMP, Bueno JMC (2009) The effect of Pt promotion on the oxi-reduction properties of alumina supported nickel catalysts for oxidative steam-reforming of methane temperature-resolved XAFS analysis. Appl Catal A 366 122-129... 

EP.12 A fuel cell system aims to produce 6.5 x lO kWh/month. It is fed with hydrogen at a rate of 1.5 x 10 kg/h. This hydrogen is generated by steam reforming with the 15% of alumina-supported nickel catalyst (MgAl204). The main reactions are described below ... 

Decreasing of the active surface by sintering and recrystallization processes. Example is the decrease of the active nickel surfaces through recrystallization on alumina-supported nickel catalysts in hydrogenation reactions. 

Lazar, M. D., Dan, M., Mihet, M., Ahnasan, V., Rednic, V., Borodi, G. (2011). Hydrogen production hy low temperature methane steam reforming using Ag and Au modified alumina supported nickel catalysts. Revue Roumaine de Chimie, 56, 637-642. 

When the formation of nickel aluminium spinel has taken place, temperatures above 800 C [389] may be required for complete reduction. Even without the presence of a spinel phase, alumina-supported nickel catalysts may show less reducibility, probably due to penetration of aluminium ions in the nickel oxide surface layers during the impregnation [364], These efforts may be aggravated by oxide additions (La203, MgO) [366], Counter diffusion of nickel and aluminium appear to be rate-determining for reduction of nickel present in spinel phases [389],... 

Chen Y, Ren J (1994) Conversion of methane and carbon dioxide into synthesis gas over alumina-supported nickel catalysts, effect of Ni-Al203 interactions. Catal Lett 29 39-48... 

Retention of BET surface area of gamma alumina supported nickel catalyst and the bare carrier after standard reduction standard reduction (duplo) reduction followed by Ih treatment in moist hydrogen at reduction temperature the bare support the support treated under reduction conditions the support reduced and treated for Ih in moist hydrogen, respectively. 

The major mechanism leading to poor metal dispersion of alumina supported nickel catalysts is hydrothermal sintering of Ni precursors prior to reduction. Sintering of the support or metal crystallites once formed are relatively unimportant. 

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