Catalytic properties of transition metal carbides II. Activity of bulk mixed carbides of molybdenum and tungsten in hydrocarbon conversion

Leclercq, Loı̈c; Provost, M.; Pastor, H.; Leclercq, G.

doi:10.1016/0021-9517(89)90349-7

Cited by 79 publications

(30 citation statements)

References 21 publications

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“…Since Levy and Boudart demonstrated that tungsten carbide (WC) exhibited catalytic activity similar to Pt [1], metal carbide based catalysts have attracted a significant amount of attention due to their catalytic similarity to noble metal catalysts [2][3][4][5]. Along with WC, molybdenum carbide (Mo 2 C) catalysts have been one of the primary carbides studied, particularly for reactions involving hydrocarbons [6][7][8][9][10][11]. After Green and coworkers demonstrated that WC and Mo 2 C catalyzed methane reforming reactions with activities comparable to Ir and Ru [12][13][14][15][16][17], studies of methane and hydrocarbon reforming catalyzed by Mo 2 C have become a popular vein of research [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Tunable Syn-gas ratio via bireforming over coke-resistant Ni/Mo2C catalyst

Brush

Evans

Mullen

et al. 2016

Fuel Processing Technology

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This study demonstrates the ability of Ni/Mo 2 C to catalyze the Methane Bireforming Reaction (combined Dry Methane Reforming Reaction, CH 4 + CO 2  2H 2 + 2CO, and Steam Methane Reforming Reaction, CH 4 + H 2 O  3H 2 + CO). By varying the ratio of CO 2 :H 2 O, the resulting H 2 :CO ratio could be tuned from 0.91 to 3.0, covering a wide range of Syn Gas (H 2 + CO) ratios relevant to various hydrocarbon syntheses. We also document the unusual deactivation behavior of Ni/Mo 2 C in this system. The catalytic activity would change from very high (greater than 50% conversion) to very low (less than 10% conversion) within 10 minutes. Despite running under conditions typically favorable for coking with a Ni catalyst (high temperature, 950°C, and excess methane), XRD, TGA, TEM, SEM, and EDX results clearly show no evidence of coking during the reaction or after deactivation. In addition, the changes to the Ni/Mo 2 C catalyst seen after deactivation (oxidation of Mo 2 C to MoO 2 , Ni-phase changes, and catalyst morphology changes) could not be seen in the catalyst subjected to reaction conditions that were halted before deactivation could occur. This suggests a sudden, rapid deactivation "event" occurs in this catalytic system as opposed to gradual catalyst deactivation, a behavior more typically seen with catalysts.

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Section: Introductionmentioning

confidence: 99%

Tunable Syn-gas ratio via bireforming over coke-resistant Ni/Mo2C catalyst

Brush

Evans

Mullen

et al. 2016

Fuel Processing Technology

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“…Striking similarities have been reported between the catalytic properties of W carbides and Pt group metals for hydrocarbon conversion reactions including dehydrogenation [1][2][3], isomerization [3][4][5][6][7][8] and hydrogenolysis [ 2,3,[5][6][7][8]. Early studies indicated that the selectivities over low surface area carbides were similar to those over supported Pt group metals for the reactions of neopentane, n-hexane, nheptane and cyclohexane, but the reaction rates were 1-4 orders of magnitude lower [2][3][4]. Recent advances in the synthesis of high surface area materials have led to the preparation of carbides with reaction rates comparable to those of Pt group metals for the aforementioned reactions [5][6][7][8]; however, their selectivities are typically different.…”

Section: Introductionmentioning

confidence: 99%

“…Recent advances in the synthesis of high surface area materials have led to the preparation of carbides with reaction rates comparable to those of Pt group metals for the aforementioned reactions [5][6][7][8]; however, their selectivities are typically different. There is evidence that the preparation conditions affect the surface composition [2,8]. The carbon stoichiometry in the carbide lattice in turn influences the catalytic and electronic properties [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

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Carbon-hydrogen bond activation over tungsten carbide catalysts

Curry¹,

Thompson²

1994

Catalysis Today

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Tungsten carbides with surface areas ranging from 4 to 39 m2/g were prepared by the temperatureprogrammed carburization of tungsten oxide and nitride powders with pure CH 4 or a 48.9% CH4 in H 2 mixture. Oxygen uptakes on the carbides were low most likely because of the presence of graphitic carbon at the surface. Nevertheless, the carbides were active and selective for the dehydrogenation of butane at temperatures between 623 and 723 K and atmospheric pressure with and without n 2 in the reactant feed. With H2 in the feed, the higher surface area carbides (_> 36 m2/g) were as active as a Pt-Sn/"y-A1203 catalyst, but their selectivities were different. Without H 2 in the feed, the selectivities of the carbides were similar to those of the Pt-Sn/'y-Al203 catalyst, but their reaction rates were 1-3 orders of magnitude lower. The high surface area materials were also active for the hydrogenolysis of butane. Because the catalytic properties of the carbides varied with the average particle size, we concluded that butane dehydrogenation was structure-sensitive over these materials, and suspected that this behavior was due to variations in the surface stoichiometry as well as the particle faceting.

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“…The catalytic properties have motivated extensive studies on electronic [8][9][10][11] and structural properties in TMC bulk and surfaces [12][13][14][15][16][17][18] in order to understand from a microscopic point of view, which factors are responsible for the enhancement of the catalytic properties and the role played by the addition of carbon atoms to transition metals. NaCl-type structure compounds from the fourth and fifth group TMC have been the subject of extensive investigations on the electronic structure, and some similarities were found for this class of compounds such as the overlap between valence and conduction bands [9,10] and a strong hybridization of the non-metal p orbitals and the metal d orbitals [10,11,18].…”

Section: Introductionmentioning

confidence: 99%

Electronic Properties and Chemical Bonding of Orthorhombic Chromium Carbide

Posada-Amarillas

Galvn

Castilln

et al. 2002

phys. stat. sol. (b)

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Subject classification: 71.20.Lp; S1.61The electronic properties of an orthorhombic phase of chromium carbide are calculated by the extended Hü ckel tight-binding method. We found in this phase similar trends in band structure and total and p-d orbital projected DOS with respect to other crystalline phases calculated previously. The bonding nature is analyzed in terms of the crystal orbital overlap population (COOP). The results show a high degree of metal-non-metal hybridized states contributing to the metallic nature of bonding.

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Catalytic properties of transition metal carbides II. Activity of bulk mixed carbides of molybdenum and tungsten in hydrocarbon conversion

Cited by 79 publications

References 21 publications

Tunable Syn-gas ratio via bireforming over coke-resistant Ni/Mo2C catalyst

Tunable Syn-gas ratio via bireforming over coke-resistant Ni/Mo2C catalyst

Carbon-hydrogen bond activation over tungsten carbide catalysts

Electronic Properties and Chemical Bonding of Orthorhombic Chromium Carbide

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