Activation of CH4 and Its Reaction with CO2 over Supported Rh Catalysts

Erdöhelyi, András; Cserényi, J.; Solymosi, F.

doi:10.1006/jcat.1993.1136

Cited by 401 publications

(121 citation statements)

References 19 publications

(26 reference statements)

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“…Positive reaction orders for CH4 and C02 were reported. Rates of product formation in methane reforming with supported Rh catalysts were found to be independent of support at pCO2/pCH4> 1 [15]. Erdbhelyi et al also studied the importance of carbon formation in the methane reforming and recognized that two different types of carbon are formed on the catalyst surface at conditions of methane excess in the feed [16].…”

Section: (1)mentioning

confidence: 95%

Reaction kinetics of the CO₂ reforming of methane

1997

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The kinetics of the C02 reforming of methane was investigated in the temperature range 700 -850 OC at normal pressure with a 1 : 1 mixture of CH4 and C02 on Ir/A1203 catalysts. The feed composition was kept constant to avoid a change in mechanism associated with composition changes. Various rate models were fitted to the experimental data by numerically integrating the rate equations. All rate models included the reverse water gas shift reaction as the most important side reaction at these reaction conditions. The best agreement was obtained with a rate model based on the stepwise mechanism, where in the ratedetermining step methane is decomposed to hydrogen and active carbon followed by the direct and fast conversion of this active carbon with C02 to 2 CO. This model is also the first and only one containing a complete subset of reactions necessary to describe the network of reactions known to occur at these reaction conditions. Comparable fit quality was obtained with a simple first order model and with a model based on a Langmuir-Hinshelwood rate expression, where the latter provided physically meaningless parameters. Values of the reaction parameters are given for the 5 best rate models studied.

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Section: (1)mentioning

confidence: 95%

Reaction kinetics of the CO₂ reforming of methane

1997

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“…Although noble metals (e.g. : Ru, Rh, Pt, Pd) show high conversion and slow deactivation rates and minimal coke formation [3], [7], [8], [9], use of nickel catalyst would be more feasible because of its lower price and higher abundance. Unfortunately, carbon deposits more readily form on nickel than on noble metal surfaces during the reaction leading to fast deactivation of the catalyst [10].…”

Section: Introductionmentioning

confidence: 99%

Carbon dioxide reforming of methane over Ni–In/SiO2 catalyst without coke formation

Károlyi

Németh

Evangelisti

et al. 2018

Journal of Industrial and Engineering Chemistry

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Keywords dry reforming of methane, silica supported nickel catalyst, nickel-indium bimetallic catalyst, coke formation, biogas conversion Highlights· Ni-In/SiO 2 catalysts were prepared by deposition-precipitation with urea. · Both metals were in metallic state after reduction at 700 °C. · Interaction of the two metals was evidenced by TPR, XPS. · The presence of indium in the close vicinity of nickel prevents coke formation. Graphical abstract AbstractThe development of a carbon tolerant nickel catalyst for carbon dioxide reforming of methane (dry reforming of methane, DRM) has been in the focus of catalysis research for several years.In the present study, 3wt%Ni/SiO 2 and bimetallic 3wt%Ni-2wt%In/SiO 2 catalysts (corresponding to 3:1 Ni:In ratio) were prepared by deposition precipitation with urea. Our intention was to modify the nickel surface with a second metal which is known from its ability to reduce surface coke formation. A methane rich reaction mixture (CH 4 :CO 2 :Ar = 2 69:30:1) was used for the catalytic tests at 600 °C and 675 °C. TPO measurements after the catalytic tests showed that there was no surface carbon formation on the indium containing catalyst.Temperature-programmed reduction measurements of the catalysts showed that both nickel and indium was completely reduced after one hour reduction at 700 °C suggesting interaction of the two metals. CO pulse chemisorption experiments revealed that the particle size was similar on the monometallic and bimetallic catalyst, and CO-TPD measurements showed completely different desorption behavior of CO, suggesting the presence of different active sites on the two catalysts. XPS experiments gave similar results, furthermore it was found that after reduction, the Ni/In ratio on the surface was 2.2 compared to the initial value (~3), which refers to the surface enrichment of indium in the bimetallic particles.The lack of coke formation on the indium containing catalyst might be explained by the interplay between a geometric and a chemical effect, that is, indium atoms are most likely situated on the edge and step sites of a nickel particle, influencing reactant adsorption and hindering the growth of carbon nanostructures and/or providing an oxygen rich indium suboxide surface through the reaction with CO 2 in the close vicinity of catalytically active nickel sites, which also inhibits the accumulation of carbon deposits during DRM.

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“…Several factors can contribute to catalyst deactivation in the synthesis gas process. These include coke formation [7][8][9][10], poisoning and transformation of active components, sintering and recombination of active components [11,12]. Among these, coke formation is the most detrimental factor because it can result in the poisoning of active centers, the clogging of the pores and even the pulverization of catalysts [13].…”

Section: Introductionmentioning

confidence: 99%

Studies on coke formation and coke species of nickel-based catalysts in CO2 reforming of CH4

Yang

et al. 2007

Catal Lett

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Three nickel-based catalyst systems, Ni/c-Al 2 O 3 , Ni/BaTiO 3 , and Ni-0.75wt%La-BaTiO 3 , were investigated for the CO 2 reforming of CH 4 . The temperature of CH 4 decomposition on catalyst Ni/c-Al 2 O 3 is the lowest and the relative content of H 2 is the highest; but the temperature of CH 4 decomposition on catalyst Ni-0.75 wt%La-BaTiO 3 is the highest and the relative content of H 2 is the lowest. The amount of carbon deposition via CH 4 decomposition decreases with the increase of rare earth La and the temperature of decomposition also declines gradually. Different active coke species were formed on different catalysts. The higher activity of coke species is, the easier the reaction with activated CO 2 is. The coke species were investigated by the XPS technique. Several surface coke species existed on catalysts after the reaction. The surface species with the binding energy near 282 and 286 ev are the main coke species. These species resulted in the catalyst deactivation. By analyzing the coke on catalyst, it was found the catalyst Ni-0.75wt% La-BaTiO 3 suppressed the formation of coke species whose binding energy is near 282 and 286 ev.

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Activation of CH4 and Its Reaction with CO2 over Supported Rh Catalysts

Cited by 401 publications

References 19 publications

Reaction kinetics of the CO₂ reforming of methane

Reaction kinetics of the CO₂ reforming of methane

Carbon dioxide reforming of methane over Ni–In/SiO2 catalyst without coke formation

Studies on coke formation and coke species of nickel-based catalysts in CO2 reforming of CH4

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Activation of CH4 and Its Reaction with CO2 over Supported Rh Catalysts

Cited by 401 publications

References 19 publications

Reaction kinetics of the CO2 reforming of methane

Reaction kinetics of the CO2 reforming of methane

Carbon dioxide reforming of methane over Ni–In/SiO2 catalyst without coke formation

Studies on coke formation and coke species of nickel-based catalysts in CO2 reforming of CH4

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Reaction kinetics of the CO₂ reforming of methane

Reaction kinetics of the CO₂ reforming of methane