Sulfur deactivation of nickel methanation catalysts

Fitzharris, W.D.; Katzer, J.R.; Manogue, W.H.

doi:10.1016/0021-9517(82)90267-6

Cited by 68 publications

(23 citation statements)

References 17 publications

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“…There were fundamental differences between the behavior of catalysts derived from the bimetallic sulfide clusters and those derived from the metal carbonyl clusters, Table 2. The methanation activities were lower than those of the reduced monometallic catalysts (Brenner, 1986), but comparable to those reported for sulfided group VIII (Agrawal, 1979; Agrawal et al, 1981 Agrawal et al, , 1982Fitzharris et al, 1982) and sulfided Mo catalysts (Concha and Bartholomew, 1983). The activities were also similar in magnitude to those of well-dispersed Fe catalysts (Jung et al, 1982).…”

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confidence: 75%

CO hydrogenation over alumina‐supported sulfide cluster catalysts

1989

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Bimetallic Mo-Fe and Mo-Co sulfide clusters were anchored on AI,O, and used for CO hydrogenation. In addition to methane, significant amounts of dimethyl ether were produced. The reaction orders obtained from power rate laws for methanation indicated that the surfaces of the catalytic ensembles were not completely saturated by CO, in contrast to the observations for most conventional CO hydrogenation catalysts. A kinetic analysis and parameter estimation was performed to identify the rate-determining step for methanation. A catalytic cycle was postulated that could account not only for the formation of methane and higher hydrocarbons, but also for dimethyl ether as a primary product. Introduction Objectives and relevanceOne of the greatest challenges in heterogeneous catalysis is to elucidate how the nature of the active site influences catalytic behavior. The adsorption of reactant molecules, the formation of reaction intermediates, and ultimately the product distribution depend on the composition and structure of the catalytic surface sites. Catalysts derived from structurally well defined organometallic clusters are very attractive model systems insofar as they are amenable to detailed spectroscopic characterization and evaluation of the intrinsic kinetics that control their catalytic behavior. These types of catalysts may also provide a link between homogeneous catalysis, where the catalytic complexes are easily identified, and heterogeneous catalysis, where the surfaces tend to be quite irregular.The objective of this study was to investigate the CO hydrogenation activities of catalysts prepared from organometallic sulfide clusters containing Mo and either Fe or Co. Although the late transition metals are the most active catalysts for CO hydrogenation, they tend to be nonselective, with product distributions following the Anderson-Schulz-Flory relationship. The late transition metals are also extremely sensitive to poisoning by sulfur, which is a common impurity in synthesis gas. Molybdenum, on the other hand, in its oxide as well as its sulfide form exhibits remarkable tolerance to deactivation in H,S and has proven activity for CO hydrogenation. Furthermore, the addition of Fe or Co to Mo appears to beneficially effect catalyst selectivity. Consequently, discrete organometallic clusters con- taining Mo, S, and Fe (or Co) represent attractive precursor compounds for the preparation of active, sulfur tolerant C O hydrogenation catalysts. An attempt was made to identify the rate-determining step for methanation on these cluster-derived catalysts. To this end, the commonly accepted sequences of elementary reaction steps for the two most important methanation mechanisms, the CO insertion mechanism and the carbide mechanism, were evaluated. Finally, a catalytic cycle has been proposed to account for the total product distribution, including hydrocarbons and oxygenates. Significant prior workTypical commercial catalysts are prepared either by coprecipitation or by sequential adsorption of suitable precursor salt ...

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confidence: 75%

CO hydrogenation over alumina‐supported sulfide cluster catalysts

1989

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“…The elementary reaction steps proposed are reproduced below and consist of two mechanisms: C formation (Steps 1-3) and C methanation (Steps 4-6). CO dissociation (Step 2), which was originally proposed by Fitzharris et al [61], was the rate-determining step based on the activation energies for every step (1.27 eV for CO 2 dissociation, 2.97 eV for CO dissociation, 0.72 eV for methylidyne, 0.52 eV for methylene and 0.50 eV for methane):…”

Section: Introductionmentioning

confidence: 99%

Insights into the mechanisms of CO2 methanation on Ni(111) surfaces by density functional theory

Ren

Guo

Yang

et al. 2015

Applied Surface Science

174

128

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a b s t r a c tThe different mechanisms of CO 2 methanation on Ni(111) surfaces have been investigated by density functional theory with and without the formation of CO as an intermediate. The most stable adsorption configurations of all reaction species (O, OH, CO, CH, CH 2 , CH 3 , CH 4 , HCOO, C(OH) 2 , CH 2 O, etc.) in three paths of CO 2 methanation adsorbed on the Ni(111) surface are described. The energy barriers and reaction energies for the overall processes involved in the various paths are presented. The rate-determining steps for the three mechanisms are HCOO→CO + OH for path 1, CO → C + O for path 2 and CO 2 + 2H → C(OH) 2 for path 3 with maximum energy barriers of 306.8 kJ/mol, 237.4 kJ/mol and 292.3 kJ/mol, respectively. Path 2 is therefore the optimum of the three mechanisms. The path starts with CO 2 dissociation into CO and O, CO decomposition into C and O species and C species hydrogenation to form CH 4 : CO 2 → CO + O → C + O + 4H → CH 2 + 2H → CH 3 + H → CH 4 .

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“…This was attributed to the likely formation of inactive sulfide species (e.g., NiS) or the formation of a sulfo-spinel (NiAl 2 S 4 ). The formation of such two-dimensional surface sulfides was later confirmed (83), and its free energy of formation was at least 15 kcal/mol more stable than bulk Ni 2 S 3 . Returning to Bartholomew et al (81), CO treatment followed by oxidation and low-temperature hydrogen treatment recovered only some activity.…”

Section: Effects Of Sulfurmentioning

confidence: 91%

“…Although few reports are available on the effect of sulfur during CO hydrogenation over Ni at FTS conditions, sulfur poisoning is well known from the literature on methanation (81)(82)(83)(84) and steam methane reforming (85). Nickel has long been the conventional choice for both of these processes.…”

Section: Effects Of Sulfurmentioning

confidence: 99%