Structural evolution of alumina supported Mo–W carbide nanoparticles synthesized by precipitation from homogeneous solution

Nguyen, Tuan Huy; Nguyên, Thành Vinh; Lee, Yong Joon; Safinski, Tomasz; Adesina, Adesoji A.

doi:10.1016/j.materresbull.2004.09.007

Cited by 18 publications

(7 citation statements)

References 9 publications

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“…It was evident that the carburization was a two‐step process with the formation of an intermediate oxycarbide form (low temperature peak, P1 at 730–713 K) and the final carbide phase (P2 at 820–848 K). This observation is in agreement with other studies . The Arrhenius parameters for oxycarbide and carbide phase formation estimated from the Kissinger equation (cf.…”

Section: Resultssupporting

confidence: 93%

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Evaluation of Ba‐promoted Mo carbide catalyst for Fischer–Tropsch synthesis

Arcotumapathy

Abdullah

et al. 2012

J of Chemical Tech & Biotech

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BACKGROUND Traditional FT catalysts such as Co and Fe still suffer from carbon-induced deactivation even with alkali promotion. The objective of this study was to examine the effect of Ba addition to carbon-tolerant Mo carbide since it has Pt-like characteristics and is cheaper than noble metals as an FT catalyst. RESULTSThe presence of Ba increased the Mo carbide production rate and reduced the activation energy for its formation. The promoted catalyst exhibited higher specific basic site strength and CO 2 uptake for strong basic site than that of the undoped catalyst. Both catalysts exhibited optimal reaction rate at a H 2 mole fraction of 0.75 while CO consumption rate, total olefin-to-paraffin ratio, methane suppression as well as C 5+ selectivity were improved with Ba addition. The non-standard Anderson-Schulz-Flory (ASF) product distribution observed for the Ba-doped catalyst may be due to the appearance of an additional polymerization site on the catalyst surface located in the BaMoO 4 phase. Chain growth factor was enhanced by up to 93% from 0.43 to 0.83 with the Ba-doped catalyst.CONCLUSIONS Ba promoter increased chain growth probability by about 93%. The deviation of product distribution from standard ASF plots with 2 chain growth factors for the 3wt%Ba-10%MoC 1-x /Al 2 O 3 catalyst was probably due to the presence of different active sites for chain initiation. The result is unprecedented and represents excellent opportunity for industrial exploitation of a new and relatively cheap carbon-resistant catalyst.

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Section: Resultssupporting

confidence: 93%

“…found that carburization conditions and carburizing agents influenced the physicochemical attributes, structure and catalytic performance of Mo carbide catalysts . H 2 /C 3 H 8 mixture has been used for MoC 1‐x /Al 2 O 3 catalyst synthesis with high surface area of 92–204 m g cat ‐1 from a metal sulphide precursor . Vo et al .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Ba‐promoted Mo carbide catalyst for Fischer–Tropsch synthesis

Arcotumapathy

Abdullah

et al. 2012

J of Chemical Tech & Biotech

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“…H 2 -C 3 H 8 was first used to synthesize an Al 2 O 3 -supported Mo carbide catalyst with a surface area of 92-204 m 2 g cat À1 from a metal sulphide precursor with an optimum of H 2 : C 3 H 8 = 5 : 1 for negligible surface carbon resilience on the catalyst. 8 Conventional FT catalysts are generally promoted by alkali addition. Thus, the possible substitution of expensive Pt noble metal with Mo carbide in FT catalysis may also benefit from similar promotion.…”

Section: Introductionmentioning

confidence: 99%

A potassium-promoted Mo carbide catalyst system for hydrocarbon synthesis

Vo¹,

Adesina²

2012

Catal. Sci. Technol.

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Potassium-promoted Mo carbide catalysts prepared by temperature-programmed carburization with H 2 -C 3 H 8 have been evaluated for Fischer-Tropsch synthesis (FTS). Temperatureprogrammed carburization of MoO 3 -Al 2 O 3 with a mixture of H 2 -C 3 H 8 was a two-stage conversion involving the transformation of Mo oxide to the final carbide phase via an intermediate oxycarbide phase. Compensation effect and isokinetic relationship were observed for both oxycarbide and carbide phase formation suggesting that a similar topotactic mechanism was involved in the solid phase transformation. CO seemed to adsorb more strongly than H 2 as implicated by its higher heat of desorption and site concentration. Both acid and basic centres were detected on the Mo carbide surface. The K-promoter increased site concentration for both weak and strong basic sites. The relationship between FT activity and K loading paralleled the trend in CO 2 heat of desorption with K addition. FT activity attained a maximum at about 3%K loading. CO hydrogenation over the Mo carbide catalyst was most suitably described by an enolic intermediate mechanism. A generalized kinetic model was derived for predicting the reaction rate for individual hydrocarbons as a function of chain growth propagation and olefin-toparaffin ratio.

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“…An increase in catalytic activity can be achieved if a carbide of a metal similar in properties to molybdenum (for example, tungsten carbide [13,14]) is introduced into the crystal lattice of a highly active molybdenum carbide. Tungsten carbide is characterized by a higher oxophilicity, and when it is incorporated into the structure of molybdenum carbide, the metallic properties of molybdenum carbide change [15]. The presence of a synergistic effect in binary carbide Mo 2 C-W 2 C was confirmed for many catalytic processes including hydrogen evolution reaction (HER), dry reforming of methane, and conversion of aromatic hydrocarbons [10,16,17].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Microporous Mo2C-W2C Binary Carbides by Thermal Decomposition of Molybdenum-Tungsten Blues

Гаврилова

Myachina

Dyakonov³

et al. 2020

Nanomaterials

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Molybdenum and tungsten carbides are perspective catalytic systems. Their activity in many reactions is comparable to the activity of platinum group metals. The development of the synthesis method for of highly dispersed binary molybdenum and tungsten carbides is an important task. Dispersions of molybdenum-tungsten blue were used as a precursor for synthesis of binary molybdenum and tungsten carbides. The synthesis of carbides was carried out by thermal decomposition of molybdenum-tungsten blue xerogels in an inert atmosphere. The binary carbides were characterized by XRD, TGA, SEM and nitrogen adsorption. The influence of the molar ratio reducing agent/Me [R]/[ΣMe], molar ratio molybdenum/tungsten [Mo]/[W] on phase composition, and morphology and porous structure of binary carbides was investigated. Samples of binary molybdenum and tungsten carbides with a highly developed porous structure and a specific surface area were synthesized.

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Structural evolution of alumina supported Mo–W carbide nanoparticles synthesized by precipitation from homogeneous solution

Cited by 18 publications

References 9 publications

Evaluation of Ba‐promoted Mo carbide catalyst for Fischer–Tropsch synthesis

Evaluation of Ba‐promoted Mo carbide catalyst for Fischer–Tropsch synthesis

A potassium-promoted Mo carbide catalyst system for hydrocarbon synthesis

Synthesis of Microporous Mo2C-W2C Binary Carbides by Thermal Decomposition of Molybdenum-Tungsten Blues

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