Selective chemisorption of carbon monoxide and hydrogen over supported molybdenum carbide catalysts

Lee, Jae Sung; Lee, Kyung Hee; Lee, Jun Young

doi:10.1021/j100180a067

Cited by 94 publications

(65 citation statements)

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“…6,15,16,[25][26][27][28][29][30] These studies can be used as references for the assignment of the IR bands of adsorbed CO on MoP. Generally speaking, linear carbonyl species coordinated to Mo δ+ (3 < δ < 5) sites exhibit ν MoC-O frequencies higher than those of free CO molecules (2143 cm -1 ).…”

Section: Ir Spectra Of Co Adsorbed On Mop/al 2 Omentioning

confidence: 99%

Carbon Monoxide Adsorption on Molybdenum Phosphides: Fourier Transform Infrared Spectroscopic and Density Functional Theory Studies

Feng

Liang

et al. 2003

J. Phys. Chem. B

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Molybdenum phosphide (MoP) and supported molybdenum phosphide (MoP/γ-Al 2 O 3 ) have been prepared by the temperature-programmed reduction method. The surface sites of the MoP/γ-Al 2 O 3 catalyst were characterized by carbon monoxide (CO) adsorption with in situ Fourier transform infrared (FT-IR) spectroscopy. A characteristic IR band at 2037 cm -1 was observed on the MoP/γ-Al 2 O 3 that was reduced at 973 K. This band is attributed to linearly adsorbed CO on Mo atoms of the MoP surface and is similar to IR bands at 2040-2060 cm -1 , which correspond to CO that has been adsorbed on some noble metals, such as platinum, palladium, and rhodium. Density functional calculations of the structure of molybdenum phosphides, as well as CO chemisorption on the MoP(001) surface, have also been studied on periodic surface models, using the generalized gradient approximation (GGA) for the exchange-correlation functional. The results show that the chemisorption of CO on MoP occurred mainly on top of molybdenum, because the bonding of CO requires a localized mininum potential energy. The adsorption energy obtained is ∆H ads ≈ -2.18 eV, and the vibrational frequency of CO is 2047 cm -1 , which is in good agreement with the IR result of CO chemisorption on MoP/γ-Al 2 O 3 .

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Section: Ir Spectra Of Co Adsorbed On Mop/al 2 Omentioning

confidence: 99%

Carbon Monoxide Adsorption on Molybdenum Phosphides: Fourier Transform Infrared Spectroscopic and Density Functional Theory Studies

Feng

Liang

et al. 2003

J. Phys. Chem. B

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“…This is because, the Mo interstices contain fourfold sites and these sites are filled first during carburisation, carbon atoms fill the interstitial sites up to one monolayer; therefore, the dissociative adsorption is completely suppressed on Mo(100)-C at low temperatures. Hence, the presence of carbon over layers on Mo (100) reduced the propensity of Mo towards CO dissociation, leading to molecular adsorption pathways [46,47]. Therefore, the observation here, where the oxide adsorbed more CO compared with that of carbide suggests molecular adsorption on the carbide.…”

Section: Resultsmentioning

confidence: 70%

“…Molybdenum in an oxidised state may form dimeric and trimeric carbonyl species depending upon the oxidation state, which may explain why the CO uptake was almost twice for the oxide compared with the carbide (Table 2). CO may be adsorbed on transition metal either dissociative or molecularly [46,47]. Dissociative adsorption readily occurs on early transition metals (such as molybdenum and tungsten), whereas molecular adsorption is observed for metals to the right of periodic table (e.g., Pt and Ru).…”

Section: Resultsmentioning

confidence: 99%

“…Dissociative adsorption readily occurs on early transition metals (such as molybdenum and tungsten), whereas molecular adsorption is observed for metals to the right of periodic table (e.g., Pt and Ru). Lee et al [47] observed dissociative adsorption for Mo, but molecular adsorption for carbon-modified Mo surfaces at 196 K (and room temperature). They have shown that for CO chemisorbed on Mo (100) with the carbon-modified Mo surfaces, adsorbed is molecular.…”

Section: Resultsmentioning

confidence: 99%

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n-Heptane hydroconversion over sulfated-zirconia-supported molybdenum carbide catalysts

2016

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Molybdenum carbide on sulfated zirconia was prepared by impregnation of MoO 3 on sulfated zirconia to give a loading of 5 wt% followed by carburisation at 923 K in a mixture of CH 4 /H 2 (4:1). The resulting catalyst was characterised by N 2 adsorption-desorption, CO chemisorption, FTIR of pyridine adsorption, XRD, TPR, TGA, Raman and SEM-EDX. This combination of characterisation studies suggests formation of a well-dispersed Mo 2 C phase over tetragonal zirconia. When employed in the hydroconversion of n-heptane, high temperature and low space velocity lead to substantial cracking. However, under some conditions, an increase in the research octane number (RON) from 0 (n-heptane) to ca. 50 was attained. Between 723 and 873 K, n-heptane is mainly cracked to iso-pentane and ethane. The product distribution as a function of conversion suggests that the reaction did not simply follow a consecutive reaction pathway, but that other parallel routes were involved.

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“…In recent years the application of transition metal carbides and nitrides for hydrotreating reactions has been studied in great detail [6,7,8,9]. There has also been some work on supported carbides and nitrides [10,11,12,13]. However, information available on the effect of additives on transition metal carbide catalysts and their reactivity for hydrotreating reactions is very limited [14].…”

Section: Introductionmentioning

confidence: 99%

Novel Supported Bimetallic Carbide Catalysts for Coprocessing of Coal with Waste Materials

Chen¹,

Cox²,

Allen³

et al. 1998

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Selective chemisorption of carbon monoxide and hydrogen over supported molybdenum carbide catalysts

Cited by 94 publications

References 0 publications

Carbon Monoxide Adsorption on Molybdenum Phosphides: Fourier Transform Infrared Spectroscopic and Density Functional Theory Studies

Carbon Monoxide Adsorption on Molybdenum Phosphides: Fourier Transform Infrared Spectroscopic and Density Functional Theory Studies

n-Heptane hydroconversion over sulfated-zirconia-supported molybdenum carbide catalysts

Novel Supported Bimetallic Carbide Catalysts for Coprocessing of Coal with Waste Materials

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