Properties of platinum-molybdenum bimetallic catalysts deposited on silica

Leclercq, G.; Romero, Trino; Pietrzyk, S.; Grimblot, J.; Leclercq, Loı̈c

doi:10.1016/0304-5102(84)80032-2

Cited by 36 publications

(15 citation statements)

References 29 publications

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“…The oxidation state of Pt and Mo and their surface repartition have been determined by XPS, ESR, hydrogen chemisorption, and the oxygen uptake during the oxidation of the prereduced catalysts. The results obtained with the Pt−Mo reduced at 500 °C have been published in ref . They will be briefly summarized in order to compare them with those obtained for catalysts reduced at 700 °C.…”

Section: Resultsmentioning

confidence: 99%

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Investigation on Active Sites in Pt−Mo on Silica Catalysts for Reactions of Hydrocarbons with Hydrogen

Leclercq¹,

Pietrzyk²,

Romero³

et al. 1997

Ind. Eng. Chem. Res.

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A series of bimetallic catalysts Pt-Mo deposited on silica, with the same (Pt + Mo) metal atom content but various Mo/Mo + Pt ratios, has been synthesized and characterized by XPS, ESR, hydrogen chemisorption, and oxygen uptake during their reoxidation after reduction, in order to determine the oxidation state of Pt and Mo and the catalyst surface compositions. They have been further tested for their activities in the dehydrogenation of cyclohexane, the hydrogenation of benzene, the hydrogenolysis of butane, and the reactions of hexane, on the one hand, and of 3-methylpentane, on the other hand, with hydrogen. Finally the kinetics of butane hydrogenolysis has been extensively studied in order to determine the equilibrium constants of butane adsorption and the rate constants of the steps of C-C bond breaking on all the Pt-Mo/SiO 2 samples. The main results are that, while Pt is completely reduced in a metal state, only a fraction of Mo, which depends only on the reduction temperature, is reduced into metal. Mo at various oxidation states is present in the same proportion for all the bimetallic catalysts. A Mo surface enrichment has been evidenced after reduction in hydrogen, but it has been shown that this enrichment decreases or even disappears in the presence of oxygen and of aromatic hydrocarbons strongly adsorbed on the metal particle surfaces. Two kinds of reactions are distinguished: cyclohexane dehydrogenation, alkanes isomerization, and cyclization, with a ratedetermining step occurring preferably on Pt, and alkanes hydrogenolysis, which is much faster on Pt-Mo because of preferential adsorption on a mixed Pt-Mo site. The nature of Pt and Mo species participating to this mixed site is discussed.

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Section: Resultsmentioning

confidence: 99%

“…The use of a dry N 2 -purged glovebox attached between the spectrometer and a reactor in which reductions in flowing hydrogen were performed allowed examination of the reduced samples without contact with air. The detailed procedure is described in ref .…”

Section: Methodsmentioning

confidence: 99%

Investigation on Active Sites in Pt−Mo on Silica Catalysts for Reactions of Hydrocarbons with Hydrogen

Leclercq¹,

Pietrzyk²,

Romero³

et al. 1997

Ind. Eng. Chem. Res.

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“…. ) with Pt-group metals are active catalysts for hydrogenation and hydrogenolysis reactions [526][527][528][529]. The large majority of the studies devoted to these systems have focused on the interaction of ultrathin metal films with atomically smooth, close packed substrates, e.g.…”

Section: Self-organized Growth Of Ni Clusters On a Cobalt-oxide Thin mentioning

confidence: 99%

Probing surface and interface morphology with Grazing Incidence Small Angle X-Ray Scattering

Renaud

Lazzari

Leroy

2009

Surface Science Reports

693

726

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“…Bimetallic structures consisting of Mo and Pt already showed higher activity than monometallic ones in hydrogenolysis of alkanes [24] and dehydrogenation of cyclohexane [25]. Lee and Choi [26] also studied the specific structure of Mo-Pt supported on γ-alumina by XAFS, highlighting both a strong interaction of Mo atoms with the support, and proving that Pt influenced the electronic state of Mo.…”

Section: Introductionmentioning

confidence: 99%

A Pt-Mo hybrid catalyst for furfural transformation

et al. 2020

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Furfural is a high-value chemical, being the precursor of compounds such as furfuryl alcohol and tetrahydrofurfuryl alcohol. Pt is known as active for furfural hydrogenation, but the high price limits its exploitation and imposes the search for alternatives. Here we presented a Pt/Mo bimetallic system with enhanced catalytic activity for furfural hydrogenation. For comparison, monometallic Mo-and Ptsupported on activated carbon have been prepared by impregnation and sol-immobilization. The bimetallic Pt/Mo was prepared impregnating the Mo-AC catalyst with Pt, using Na 2 PtCl 4 as a precursor, PVA, and NaBH 4 as reducing agent. HR-TEM analyses on Pt/Mo catalyst showed Mocontaining agglomerates embedded in the carbon matrix, displaying diffraction fringes with spacing typical of Mo 4 O 11 in the orthorhombic phase, as well as Pt nanoparticles more evenly dispersed in the Mo-AC system compared to bare AC. The Pt/Mo catalyst showed higher activity than both monometallic ones, and it converted 92 % of furfural to furfuryl alcohol and ethyl furfuryl ether with 20 % and 80 % selectivity, respectively. However, despite a lower initial activity, the monometallic Mo/AC catalyst showed a complete selectivity to the ether.

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Properties of platinum-molybdenum bimetallic catalysts deposited on silica

Cited by 36 publications

References 29 publications

Investigation on Active Sites in Pt−Mo on Silica Catalysts for Reactions of Hydrocarbons with Hydrogen

Investigation on Active Sites in Pt−Mo on Silica Catalysts for Reactions of Hydrocarbons with Hydrogen

Probing surface and interface morphology with Grazing Incidence Small Angle X-Ray Scattering

A Pt-Mo hybrid catalyst for furfural transformation

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