Generation and Reactions of CH2 and C2H5 Species on Mo2C/Mo(111) Surface

Solymosi, F.; Bugyi, László; Oszkó, A.; Horváth, István

doi:10.1006/jcat.1999.2491

Cited by 58 publications

(25 citation statements)

References 43 publications

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“…Based on the previous studies [38][39][40][41][42][43], we assume that carbon deficient sites on the Mo 2 C surface are the active centers of the catalyst. The first step of the reaction is very likely the dissociation of ethanol to ethoxy species, which is bonded with its oxygen end to the active sites of Mo 2 C [28,29].…”

Section: Decomposition Of Ethanolmentioning

confidence: 99%

Efficient H2 Production from Ethanol over Mo2C/C Nanotube Catalyst

2007

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Mo 2 C deposited on silica is an effective catalyst for the decomposition of ethanol; the extent of the reaction approached 100% even at 623-673 K. Beside H 2 several C-containing compounds were produced, which caused the low yield of hydrogen. Preparation of Mo 2 C by the reaction of MoO 3 with multiwall carbon nanotube, however, dramatically altered the product distribution. The formation of hydrogen came into prominence; about 40% of hydrogen content of ethanol decomposed at 523-723 K has been converted into H 2 . Another feature of the Mo 2 C/C nanotube is the relatively slow deactivation. Adding water to ethanol further enhanced the hydrogen production.

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Section: Decomposition Of Ethanolmentioning

confidence: 99%

Efficient H2 Production from Ethanol over Mo2C/C Nanotube Catalyst

2007

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“…Following the reports for copper surfaces, additional examples of the migratory coupling and/or insertion of methylene have been reported [10][11][12][13][14], including a thorough RAIRS investigation of the insertion step on Ag(111) [11].…”

Section: Introductionmentioning

confidence: 99%

Methylene migration and coupling on a non-reducible metal oxide: The reaction of dichloromethane on stoichiometric α-Cr2O3(0001)

et al. 2015

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The reaction of CH 2 Cl 2 over the nearly-stoichiometric α-Cr 2 O 3 (0001) surface produces gas phase ethylene, methane and surface chlorine adatoms. The reaction is initiated by the decomposition of CH 2 Cl 2 into surface methylene and chlorine. Photoemission indicates that surface cations are the preferred binding sites for both methylene and chlorine adatoms. Two reaction channels are observed for methylene coupling to ethylene in temperature-programmed desorption (TPD). A desorption-limited, low-temperature route is attributed to two methylenes bound at a single site. The majority of ethylene is produced by a reaction-limited process involving surface migration (diffusion) of methylene as the rate-limiting step. DFT calculations indicate the surface diffusion mechanism is mediated by surface oxygen anions. The source of hydrogen for methane formation is adsorbed background water. Chlorine adatoms produced by the dissociation of CH 2 Cl 2 deactivate the surface by simple site-blocking of surface Cr 3+ sites. A comparison of experiment and theory shows that DFT provides a better description of the surface chemistry of the carbene intermediate than DFT+U using reported parameters for a best representation of the bulk electronic properties of α-Cr 2 O 3 .

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“…In subsequent works it turned out that Mo 2 C on ZSM-5 can also catalyze or effectively promote aromatization of C 2 -C 8 alkanes, 20-27 ethanol, 28 methanol, 29 and dimethyl and diethyl ether, 30 which required the study of the chemistry of their primary dissociation products. [31][32][33][34][35][36][37] In a continuation of this research program we undertook the evaluation of the effects of potassium, the wellknown promoter of catalytic reactions of hydrocarbons, on the stability and reaction pathways of hydrocarbon fragments, CH 2 and C 3 H 7 on Mo 2 C/Mo(100) surface. 33,34 In the present paper we report the effect of potassium on the adsorption and dissociation of CH 3 I and C 2 H 5 I and on the chemistry of CH 3 and C 2 H 5 species on the same surface.…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Reaction of Methyl and Ethyl Iodide on Potassium-Promoted Mo₂C/Mo(100) Surface

et al. 2008

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X-ray photoelectron spectroscopy (XPS) studies revealed that potassium on Mo 2 C/Mo(100) induced cleavage of the C-I bond in adsorbed CH 3 I even at ∼100 K. The temperature of complete C-I bond breaking occurred 60-80 K lower compared to the clean surface. Preadsorbed potassium also influenced the reaction pathway of adsorbed CH 3 formed. It decreased its self-hydrogenation into methane and facilitated the coupling reactions into ethane and ethylene below 200 K. High-resolution electron energy loss spectroscopy (HREELS) confirmed formation of adsorbed CH 3 species and revealed its thermal stability. Potassium exerted a similar influence on the chemistry of C 2 H 5 I on Mo 2 C/Mo(100) surface. Rupture of the C-I bond also occurred more easily on K-covered surface. Ethyl species, the primary product of the dissociation, dehydrogenated into ethylene on one hand and hydrogenated into ethane on the other. Rupture of the C-C bond was not observed even at high potassium coverage. Illumination of coadsorbed layers promoted further dissociation of the C-I bond in both compounds at ∼100 K.

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Generation and Reactions of CH2 and C2H5 Species on Mo2C/Mo(111) Surface

Cited by 58 publications

References 43 publications

Efficient H2 Production from Ethanol over Mo2C/C Nanotube Catalyst

Efficient H2 Production from Ethanol over Mo2C/C Nanotube Catalyst

Methylene migration and coupling on a non-reducible metal oxide: The reaction of dichloromethane on stoichiometric α-Cr2O3(0001)

Adsorption and Reaction of Methyl and Ethyl Iodide on Potassium-Promoted Mo₂C/Mo(100) Surface

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Generation and Reactions of CH2 and C2H5 Species on Mo2C/Mo(111) Surface

Cited by 58 publications

References 43 publications

Efficient H2 Production from Ethanol over Mo2C/C Nanotube Catalyst

Efficient H2 Production from Ethanol over Mo2C/C Nanotube Catalyst

Methylene migration and coupling on a non-reducible metal oxide: The reaction of dichloromethane on stoichiometric α-Cr2O3(0001)

Adsorption and Reaction of Methyl and Ethyl Iodide on Potassium-Promoted Mo2C/Mo(100) Surface

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Adsorption and Reaction of Methyl and Ethyl Iodide on Potassium-Promoted Mo₂C/Mo(100) Surface