Hydrogenation of surface carbon on alumina-supported nickel

McCarty, J.G.; Wise, Henry

doi:10.1016/0021-9517(79)90007-1

Cited by 378 publications

(117 citation statements)

References 33 publications

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“…Adsorbed carbon atoms on group VIII metals are reaction intermediates [1][2][3][4][5][6] in the formation of hydrocarbons from synthesis gas. The formation of carbonaceous intermediates from CO disproportionation on these metals has been studied [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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The reactivity of adsorbed carbon on vanadium promoted rhodium catalysts

Koerts¹,

Santen²

1990

Catal Lett

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Rhodium/vanadium catalyst, promoter action, adsorbed carbon, metal-carbon bond strength, carbon chain growth, quantum theoretical calculationsThe hydrogenation reactivity of surface carbon deposited by CO decomposition was investigated for a rhodium-vanadium catalyst. It appeared that the rate of methanation of reactive surface carbon is decreased by vanadium. The reactivity towards C2+ hydrocarbons is enhanced by vanadium. The relation between stronger adsorbed carbon atoms and the formation of higher hydrocarbons is discussed. ASED calculations support the proposal that changes in metal-carbon bond strength have a significantly larger effect on the rate of methanation than on carbon chain growth.

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Section: Introductionmentioning

confidence: 99%

“…The formation of carbonaceous intermediates from CO disproportionation on these metals has been studied [7][8][9]. On rhodium three types of carbon [10][11][12][13][14] can be produced from CO adsorption at temperatures above 250 ~ C: C~, Cr and Cv.…”

Section: Introductionmentioning

confidence: 99%

The reactivity of adsorbed carbon on vanadium promoted rhodium catalysts

Koerts¹,

Santen²

1990

Catal Lett

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“…Based on the TPR profiles in Figures 6b and 9, CH 4 and CO evolution may be interdependent on the surface of the Ni catalyst. Indeed, several surface carbon species have been identified from the CO hydrogenation reactivity of Ni catalysts at conditions similar to those in the current study [86]. Such surface carbons or surface carbidic species that may be present in the current study may cause electronic perturbations [74,87] and geometrical modifications [73,88], and thus affecting the activity of the Ni catalyst.…”

Section: The Effect Of the Subsequent Treatment To The Cnf/ac Compositementioning

confidence: 90%

Controlling the yield and structure of carbon nanofibers grown on a nickel/activated carbon catalyst

Rinaldi

Abdullah

Ali

et al. 2009

Carbon

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Carbon nanofibers (CNFs) were grown via the chemical vapor deposition of C2H4 on an activated carbon (AC)-supported Ni catalyst. The texture of the CNF/AC composites can be tuned by varying the growth temperature and by treatment in reducing atmosphere prior to C2H4/H2 exposure. The Ni-catalyzed gasification of the AC support increases the microporosity of the composite and shown to be dominant throughout the composite synthesis especially during reduction, subsequent treatment in reducing atmosphere, and CNF growth at low temperatures. N2 isotherm and scanning electron microscope were used to characterize the texture and morphology of the composites. Subsequent treatment in reducing atmosphere were shown to increase the Ni catalyst activity to grow CNFs. High resolution transmission electron microscope however did not reveal any microstructural difference for Ni catalyst with and without the subsequent reduction treatment. We propose in this paper that the carbon dissolutions during treatment of the catalyst might have an implication on the CNF growth.

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“…The profiles reveal the existence of two peaks. These peaks are assigned to two different carbon species according to the work of McCarthy and Wise [39]. The first carbon species, hydrogenating between 100 and 200 °C, is assigned to atomic carbon or to strongly chemisorbed CO [40][41][42].…”

Section: Carbon Formationmentioning

confidence: 99%

“…The second carbon species, hydrogenating between 400 and 600 °C is assigned to polymeric carbon. This carbon species, also called "C β " or "gum", is responsible for deactivation [4,34,39,40,43].…”

Section: Carbon Formationmentioning

confidence: 99%

Deactivation of Ni/γ-Al2O3 Catalysts in CO Methanation: Effect of Zr, Mg, Ba and Ca Oxide Promoters

et al. 2017

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reserves [1,2]. The SNG production process involves two steps: gasification of the carbon-containing feedstock and subsequent catalytic methanation of the resulting synthesis gas. Methanation of synthesis gas involves the two following reactions [3][4][5]:These reactions are thermodynamically favored at low temperature and high pressure [6]. It is therefore that the methanation process is designed to effectively remove the heat of reaction and thus maximize the methane yield [1,7]. There are currently two main methanation concepts: single fluidized bed reactors and series of adiabatic fixed bed reactors with intercooling [1]. The latter, also known as high temperature methanation, has already found commercial application [8,9].Alumina-supported nickel catalysts are usually employed in this application due to their high activity, selectivity to methane and relatively low price [7]. However, their stability is threatened by the severe conditions of the high temperature methanation process [10,11]. In this process, the catalyst at the inlet of the reactor is exposed to low temperatures and high CO partial pressures, fact that favors the formation of polymeric carbon and sintering via nickel carbonyl formation [4,[12][13][14]. The exothermic reactions cause a significant temperature rise. As a result, the major part of the catalyst in these reactors is exposed to high temperatures and high steam partial pressures fact that promotes sintering of the nickel nanoparticles and the support [11,15]. In order to limit the temperature rise and thus, catalyst deactivation, a high gas recycle is used in these reactors. Catalysts with improved stability at low andAbstract Catalyst deactivation is one of the major concerns in the production of substitute natural gas (SNG) via CO methanation. Catalysts in this application need to be active at low temperatures, resistant to polymeric carbon formation and stable at high temperatures and steam partial pressures. In the present work, a series of aluminasupported nickel catalysts promoted with Zr, Mg, Ba or Ca oxides were investigated. The catalysts were tested under low temperature CO methanation conditions in order to evaluate their resistance to carbon formation. The catalysts were also exposed to accelerated ageing conditions at high temperatures in order to study their thermal stability. The aged catalysts lost most of their activity mainly due to sintering of the support and the nickel crystallites. Apparently, none of these promoters had a satisfactory effect on the thermal resistance of the catalyst. Nevertheless, it was found that the presence of Zr can reduce the rate of polymeric carbon formation.

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Hydrogenation of surface carbon on alumina-supported nickel

Cited by 378 publications

References 33 publications

The reactivity of adsorbed carbon on vanadium promoted rhodium catalysts

The reactivity of adsorbed carbon on vanadium promoted rhodium catalysts

Controlling the yield and structure of carbon nanofibers grown on a nickel/activated carbon catalyst

Deactivation of Ni/γ-Al2O3 Catalysts in CO Methanation: Effect of Zr, Mg, Ba and Ca Oxide Promoters

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