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Nickel catalysts supports

A selective poison is one that binds to the catalyst surface in such a way that it blocks the catalytic sites for one kind of reaction but not those for another. Selective poisons are used to control the selectivity of a catalyst. For example, nickel catalysts supported on alumina are used for selective removal of acetjiene impurities in olefin streams (58). The catalyst is treated with a continuous feed stream containing sulfur to poison it to an exacdy controlled degree that does not affect the activity for conversion of acetylene to ethylene but does poison the activity for ethylene hydrogenation to ethane. Thus the acetylene is removed and the valuable olefin is not converted. [Pg.174]

Ethylamines. Mono-, di-, and triethylamines, produced by catalytic reaction of ethanol with ammonia (330), are a significant outlet for ethanol. The vapor-phase continuous process takes place at 1.38 MPa (13.6 atm) and 150—220°C over a nickel catalyst supported on alumina, siUca, or sihca—alumina. In this reductive amination under a hydrogen atmosphere, the ratio of the mono-, di-, and triethylamine product can be controlled by recycling the unwanted products. Other catalysts used include phosphoric acid and derivatives, copper and iron chlorides, sulfates, and oxides in the presence of acids or alkaline salts (331). Piperidine can be ethylated with ethanol in the presence of Raney nickel catalyst at 200°C and 10.3 MPa (102 atm), to give W-ethylpiperidine [766-09-6] (332). [Pg.415]

Some nickel catalysts supported on phosphinated silica were shown to be superior to their homogeneous analogs (224). [Pg.235]

Other products were dimethyl ether (DME), methane and carbon dioxide. The data in Table I show that high yields of carbonylated products were produced with nickel catalysts supported on activated carbon and carbon black. Other nickel catalysts gave mainly methane and dimethyl ether. It is clear that a carbonaceous carrier is essential for the appearance of carbonylation activity for the nickel catalyst. The role of the carbonaceous carrier will be discussed later. [Pg.209]

Liquid-phase hydrogenation of 1,4 butynediol to cis-1,4-butenediol and 1,4-butanediol has been carried out on nickel catalysts supported on thirteen different supports. Some commercial nickel catalysts were used as references. Furthermore, metal loading and Ni-Cu alloying have also been studied. The results obtained indicates that catalytic activity, selectivity and metal surface area of catalysts are closely correlated to some textural and/or acid-base properties of the corresponding support. Similarly, the influence of Cu as a second metal in catalyst behaviour is also related to the nature of the support. [Pg.269]

Carlu, J. C. and Caze, C. Dimerization of ethylene catalyzed by a nickel-catalyst supported on porous polymers. React. Polym., 1990, 13, 153-160. [Pg.140]

Steam reforming runs at 650-1000°C, typically on a nickel catalyst supported on alumina and typically runs at about 95 % of completion. [Pg.416]

The effect of alkali metal on the catalytic gasification of rice straw over nickel catalysts supported on kieselguhr... [Pg.358]

Abstract Rice straw was catalytically gasified over nickel catalysts supported on kieselguhr. This has been done by varying the content of alkali carbonate, lithium metal (3-20wt%) and various sodium compounds. In the case which alkali metal carbonates were separately added with nickel catalyst, conversion to gas was increased in the following order of Li< Cs< Kalkali metals were used to as co-catalyst by impregnation method, gas formation was increased in the following order Cs< tC a< Li. These results showed same aspects with TPR patterns. [Pg.358]

A wide variety of metallic and bi-metallic catalysts are available in the market. The most prominent are nickel catalysts supported in various matrices, namely acidic AljOj. These catalysts are very cflTicient in reforming even heavy tar to CO and Hj. Simultaneous partial reforming of the synthetic gas cannot be avoided but it is not usually detrimental to the gas quality. [Pg.1677]

Impregnation has been used to prepare a number of catalysts having different metal support combinations. Highly loaded nickel catalysts supported on alumina, titania, silica, niobia and vanadium pentoxide were prepared by adsorption of nickel nitrate from an ammoniacal solution onto the support material. The supported salts were dried at 120°C and calcined at 370°C before reduction to the supported metallic nickel. It was found that the ease of reduction depended on the crystallinity of the support. Amorphous or poorly crystalline supports made the reduction of the nickel oxide more difficult than on crystalline supports. As examples of its generality, this procedure was also used to prepare... [Pg.277]

Amorphous Ni-(40-x) at% Zr-x at% RE (x = 0, 1, 5 and 10 RE = Y, Ce and Sm) alloy ribbons of about 1 mm width and about 20 pm thickness were prepared by a single-roUer melt spinning method. The structure of the alloys prepared was confirmed by X-ray diffraction with Cu K radiation. The amorphous alloy ribbons were oxidized at 773 K in air for 5 hours and then reduced at 573 K imder flowing hydrogen for 5 hours. During this treatment the amorphous aUoys transformed to nickel catalysts supported on zirconia or zirconia-rare earth element oxides. [Pg.262]

The nano-grained nickel catalysts supported on zdrconia or zirconia-rare earth element oxides are prepared by the oxidation-reduction pretreatment of amorphous Ni-Zr-rare earth element alloys. The conversion of carbon dioxide to methane on the catalyst prepared from amorphous Ni-40Zr alloy is improved by the addition of 5 at% or more rare earth elements (Y, Ce and Sm). [Pg.266]

To investigate the effect of micropores, we conducted electrolyses using the following catalysts, unmodified ACF, iron and nickel catalysts supported on non-activated carhon fibers (CF/Fe, CF/Ni), iron catalyst supported on activated carhon fibers (ACF/Fe) and two types of nickel catalysts supported on activated carbon fibers (ACF/Ni-1, ACF/Ni-2). Table 1 shows the reduction product distributions for the various catalysts at -1.8V vs. SCE. The ACF catalyst itself has very fittle activity for CO2 reduction, and hydrogen evolution was the principal reaction. The CF/Fe and CF/Ni catalysts showed very little activity as well. [Pg.587]

Summarizing all the information obtained above, the course of formation of the nickel catalyst supported on AI2O3 is pictured in Fig. 5. The dried nickel hydroxide decomposes into nickel oxide, a part of which combines with carrier alumina and forms nickel aluminate in the interface of the two solid phases. [Pg.104]

The traditional treatment of nitrobenzene (1) with iron and acid, called Bechamp reduction, was employed almost exclusively in the production of aniline (2) and many aromatic amines until the 1960s1,2 (Scheme 1). The reduction is straightforward, and can also be achieved by catalytic hydrogenation, sodium sulfide reduction and zinc reduction with caustic soda. Nitrotoluenes and nitroxylenes are hydrogenated under pressure over a nickel catalyst supported on kieselguhr. The sulfide reduction is useful in selective reduction, such as of m-dinitrobenzene to m-nitroaniline. [Pg.718]

TPH tests with pure alumina (alpha) indicated that sulfur was not adsorbed on this material during fixed-bed poisoning tests, although sulfur adsorbed on nickel catalysts supported on alumina, thus indicating it adsorbs on the surface of nickel only. Tests with a pure alumina (alpha) bed also indicated that hydrogen was not adsorb on it at the conditions for nickel surface area measurements by hydrogen. [Pg.475]

Different nickel-based catalysts on ceramic supports have been extensively investigated as internal reforming catalysts. Ni/MgO or Ni supported or AI2O3 provide sufficient catalytic activity for the steam reformation reaction. It possesses the stability and converts about 85 /o CH4 to H2 at 650°C. But it is deactivated by the alkali metal cations of the electrolyte. No thorough study has been made on the suitability of available catalysts besides nickel. Ni-cermet anodes are suggested as alternatives. Nickel catalyst supported with y-LiA102 was also used to study the steam reforming of methane in internally reformed... [Pg.1759]

Catalyst support such as C0/AI2O3 and Rh/Al203 were used for the production of hydrogen from ethanol for internal reforming MCFC application. Research is also focused on the use of nickel catalyst supported on Mg0-Ti02 composite oxide with varying ratio of Mg to Ti. ... [Pg.1759]

The aim of the present article is to report the large scale (several hundred grams per gram of active phase) synthesis of uniform carbon nanofibers (average diameter ranging between 40 and 60 nm) by the catalytic decomposition of a mixture of ethane and hydrogen over a nickel catalyst supported on carbon nanotubes. To illustrate their catalytic potential, the as-synthesized carbon nanofibers are subsequently used as catalyst support for palladium in the hydrogenation of nitrobenzene in a liquid phase reaction. [Pg.194]

The most fi equently applied method to prepare nickel catalysts supported by mesoporous materials is incipient wetness impregnation [e.g. 5-7]. Only for this method nickel catalysts with loadings exceeding 5 wt% have been reported [5-7]. Usually a very... [Pg.647]

Syngas production - steam methane reforming, SMR Steam and natural gas are reacted at high temperature (800-1000°C) and moderate pressure (20-30 bar) over a nickel catalyst supported on alumina to give Reaction sequence (2.5) ... [Pg.42]

The activities of nickel catalysts supported on a variety of carrier materials were investigated (Fig. 1). While the catalytic activity of Ni was quite low when it was supported on SiOj, AljOj, and TiOj, that of Ni supported on carbonaceous carrier such as carbon black or active carbon was excellent, its activity was apparently proportional to the specific surface area of the carrier. It can be concluded that carbon is essential for the appearance of the carbonylation activity of nickel catalyst. The role of carbonaceous carrier is most probably attributed to its electron donor-acceptor characters as demonstrated in Fig. 2. [Pg.246]

Other and quite noticeable effects are also obtained in the activity of the catalyst by the use of certain supporting materials. Tims, a nickel catalyst supported on alumina is subjected to an effect similar to that of a protective colloid or a colloidal sol in that the reduced nickel is able to withstand higher temperatures without sintering or loss in activity and... [Pg.24]

Takahashi et al. (1986) investigated the hydrogenation of benzene, mono-, di-, and trimethyl benzenes over nickel catalysts supported on... [Pg.58]

Extensive experimental and kinetic modelling work on these reactions carried out by Zmcevic and Rusic (1988) and Takahashi etal. (1986) using a nickel catalyst supported on different materials gives strong evidence to suggest that the LHHW mechanism is more probable. [Pg.309]

The ANOF technique proved to be a promising method for obtaining eggshell catalysts with a very good mechanical and chemical resistance. By appropriate choice of the metallic substrate, electrolyte composition and anodization conditions, catalysts with tailor-made pore structure, pore density, pore length, and compositions can be controlled. The nickel catalysts supported on alumina, magnesia or titania were found to be efficient for the selective oxydehydrogenation of cyclohexane to cyclohexene. [Pg.210]

Liquid-phase selective hydrogenation of ethyl linolate to ethyl oleate has been carried out on nickel catalysts supported on sepiolite as well as on several different supports. The influence of metal loading and Ni-Cu alloying has been studied as well. The results indicate that catalytic activity and selectivity correlate closely with some textural and/or acid-base properties of the support and selectivity increases with metal loading. Furthermore, as a general rule, Ni-Cu alloying improves in selectivity. [Pg.227]

A nickel catalyst supported by a magnesium-alumina carrier is used in the fixed bed catalytic section of the reactor [15]. Carbon formation reactions are prevented from occurring in the combustion zone by careful selection of operating conditions and a proper mixing arrangement of the process inlet streams. [Pg.62]

The nickel dispersion of the catalyst on alumina support was less than that on silica support. This may be due to the strong interaction between nickel and alumina and undeveloped support pore structure than that of silica support. However, high catalytic activity and resistance to carbon deposition were obtained on the nickel catalyst supported on alumina. This indicated that metal dispersion was not the decisive factor that influenced the catalyst performance. Actually, the catalytic performance of the catalysts were integrative effect of nickel loading, metal dispersion, support, promoter, preparation and activation. [Pg.104]

Y.H. Mo, A.K.M.F. Kibria, and K.S. Nahm, The growth mechanism of carbon nanotubes from thermal cracking of acetylene over nickel catalyst supported on alumina, Synth. Met., 122, 443 47 (2001). [Pg.253]


See other pages where Nickel catalysts supports is mentioned: [Pg.221]    [Pg.383]    [Pg.688]    [Pg.256]    [Pg.208]    [Pg.239]    [Pg.17]    [Pg.555]    [Pg.266]    [Pg.561]    [Pg.1765]    [Pg.198]    [Pg.647]    [Pg.656]    [Pg.983]    [Pg.341]    [Pg.604]   
See also in sourсe #XX -- [ Pg.123 , Pg.124 , Pg.125 , Pg.126 , Pg.127 , Pg.128 , Pg.129 , Pg.130 , Pg.131 , Pg.132 , Pg.133 ]




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Supported nickel

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