Characterization of Molybdena Catalysts

Massoth, F.E.

doi:10.1016/s0360-0564(08)60058-9

Cited by 275 publications

(63 citation statements)

References 92 publications

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“…Incorporation of V 2 O 5 leads to a consistent decrease in the specific surface area and such a decrease is more pronounced as the vanadium content increased. This is a general phenomenon of supported catalysts, where the surface area of the support decreases with increasing the quantity of the active component up to monolayer coverage of the impregnated one [22]. The decrease in surface area as a function of vanadia content must be attributed to the penetration of the active component into the pores of the support in effect, results high dispersion of the active component on the support.…”

Section: Physico-chemical Characterizationmentioning

confidence: 94%

Structural and catalytic investigation of vanadia supported on ceria promoted with high surface area rice husk silica

Radhika

Sugunan

2006

Journal of Molecular Catalysis A: Chemical

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Rice husk silica was utilized as the promoter of ceria for preparing supported vanadia catalysts. Effect of vanadium content was investigated with 2-10 wt.% V 2 O 5 loading over the support. Structural characterization of the catalysts was done by various techniques like energy dispersive X-ray (EDX), X-ray diffraction (XRD), BET surface area, thermal analysis (TGA/DTA), FT-infrared spectroscopy (FT-IR), UV-vis diffused reflectance spectroscopy (DR UV-vis), electron paramagnetic spectroscopy (EPR) and solid state magnetic resonance spectroscopies ( 29 Si and 51 V MASNMR). Catalytic activity was studied towards liquid-phase oxidation of benzene. Surface area of ceria enhanced upon rice husk silica promotion, thus makes dispersion of the active sites of vanadia easier. Highly dispersed vanadia was found for low V 2 O 5 loading and formation of cerium orthovanadate (CeVO 4 ) occurs as the loading increases. Spectroscopic investigation clearly confirms the formation of CeVO 4 phase at higher loadings of V 2 O 5 . The oxidation activity increases with vanadia loading up to 8 wt.% V 2 O 5 , and further increase reduces the conversion rate. Selective formation of phenol can be attributed to the presence of highly dispersed active sites of vanadia over the support.

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Section: Physico-chemical Characterizationmentioning

confidence: 94%

Structural and catalytic investigation of vanadia supported on ceria promoted with high surface area rice husk silica

Radhika

Sugunan

2006

Journal of Molecular Catalysis A: Chemical

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“…3. On decreasing the molybdenum concentration the intensity of the band at 240 nm, usually ascribed to monomeric tetrahedral MOO2-species [4], increases and, in addition, a decrease in the intensity of the band at 300 nm, ascribed to octahedral polymolybdate or MOO3, is observed. This might be due to a transformation of octahedrally coordinated molybdenum species, Mo(O), into tetrahedrally coordinated ones, Mo(T), although the simultaneous presence of octahedral species cannot be excluded because Mo(O) species also give rise to bands at 240 nm.…”

Section: Resultsmentioning

confidence: 97%

“…Supported oxides are extremely important materials because of their applications as catalysts [1,2]; for example, MoO3/A1203 is the precursor material for hydrotreatment catalysts [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Reactivity of MoO3: effect of molybdenum with Al2O3 precursor and the presence of water vapour on the dispersion of the surface phases

et al. 1992

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“…Generally, such weak acid sites are associated with surface hydroxyl groups of the support [43]. It is well established fact in literature that neutral, weakly acidic or basic hydroxyl groups are present over the surface of metal oxides that has been widely used as a support material [43,44]. When molybdena is impregnated over these supports, Mo cation selectively interacts with hydroxyl groups of basic nature and suitable strength, leading to the formation of monolayer patches of MoO3 on support surface [45,46].…”

Section: Bulletin Of Chemical Reaction Engineering and Catalysis 7(2)mentioning

confidence: 99%

MoO3/SiO2-ZrO2 Catalyst: Eeffect of Calcination Temperature on Physico-chemical Properties and Activities in Nitration of Toluene

Kemdeo

2012

Bull. Chem. React. Eng. Catal.

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12 wt % molybdena was deposited over 1:1 silica zirconia mixed oxide support and the resultant catalyst was calcined between the 500 to 700 oC range of temperature. The samples were characterized by XRD, FT-IR, BET, SEM, NH3-TPD and pyridine adsorbed FT-IR techniques. Nitration of toluene was studied as a model reaction over the prepared catalysts and parameters like effect of reaction temperature, effect of various solvents, catalyst reusability are studied. It was found that conversion of toluene varies with the presence of Brönsted acid sites over the catalyst surface and para-nitrotoulene selectivity is associated with pore size of the catalyst. Over the same catalysts, nitration was extended for some other aromatics. Avoid of sulfuric acid in the present process is an interesting concern in view of green chemistry. © 2012 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

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Characterization of Molybdena Catalysts

Cited by 275 publications

References 92 publications

Structural and catalytic investigation of vanadia supported on ceria promoted with high surface area rice husk silica

Structural and catalytic investigation of vanadia supported on ceria promoted with high surface area rice husk silica

Reactivity of MoO3: effect of molybdenum with Al2O3 precursor and the presence of water vapour on the dispersion of the surface phases

MoO3/SiO2-ZrO2 Catalyst: Eeffect of Calcination Temperature on Physico-chemical Properties and Activities in Nitration of Toluene

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