Phase cooperation and remote control effects in selective oxidation catalysts

Weng, Lu‐Tao; Delmon, Bernard

doi:10.1016/0926-860x(92)80093-r

Cited by 207 publications

(93 citation statements)

References 168 publications

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“…They proposed that synergetic effects in the conversion, in the yield, and in the selectivity were observed when Mg 3 (VO 4 ) 2 was mixed with Mg 2 V 2 O 7 , and explained the synergetic effect by a remote control mechanism. Weng and Delmon [22] proposed the selectivity of Mg 3 (VO 4 ) 2 can be improved by Mg 2 V 2 O 7 /MgO when there was an excess of magnesium with respect to the stoichiometry of the second phase. They summarized the explanation of the promotion effect in four principal reasons in general.…”

Section: Introductionmentioning

confidence: 99%

Oxidative Dehydrogenation of Cyclohexane to Cyclohexene over Mg-V-O Catalysts

Jin

Cheng

2009

Catal Lett

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The oxidative dehydrogenation of cyclohexane was studied over Mg-V-O catalysts with different Mg/V atomic ratios. Catalysts were prepared via citric acid complexation and characterized by N 2 -adsorption, XRD, FT-IR, Raman spectroscopy, NH 3 -TPD and H 2 -TPR techniques. Among the pure magnesium vanadates, Mg 3 (VO 4 ) 2 has the isolated active sites, weakly basic surface and lower reducibility of the metal cations, and could be recognized as the catalytic active phase. Furthermore, a series of mechanically mixed catalysts were studied in the reaction in attempting to investigate the synergetic effect. The finding revealed synergetic effects in the conversion, in the yield, and in the selectivity were observed in Mg 3 (VO 4 ) 2 mixing with a suitable amount of MgO and Mg 2 V 2 O 7 due to a solid solution of MgO in the Mg 3 (VO 4 ) 2 phase and the remote control mechanism, respectively. Among the biphasic catalysts, (7/4)MgVO catalyst exhibited a better catalytic performance, on which a cyclohexene selectivity of 45.7% at cyclohexane conversion of 13.9% was obtained.

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Section: Introductionmentioning

confidence: 99%

Oxidative Dehydrogenation of Cyclohexane to Cyclohexene over Mg-V-O Catalysts

Jin

Cheng

2009

Catal Lett

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“…[4][5][6] Enhanced catalytic activity has been 2 ascribed to amorphous materials as heterogeneous catalysts and OER electrocatalysts, [7][8][9][10][11][12][13][14][15][16][17][18] while high activity and stability has also been reported for nanostructured, multi-phase heterogeneous catalysts and electrocatalysts, with the behavior attributed to cooperative effects like spill-over or unique interfacial crystallographic structures. [19][20][21] Among the most active and investigated OER electrocatalysts in basic electrolytes are transition metal oxy hydroxides. [22][23][24][25][26][27] Their high activity is ascribed in part to volume activity of the hydrated catalyst.…”

Section: Introductionmentioning

confidence: 99%

An Operando Investigation of (Ni–Fe–Co–Ce)O_x System as Highly Efficient Electrocatalyst for Oxygen Evolution Reaction

et al. 2017

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Abstract. The oxygen evolution reaction (OER) is a critical component of industrial processes such as electrowinning of metals and the chlor-alkali process. It also plays a central role in the developing renewable energy field of solar-fuels generation by providing both the protons and electrons needed to generate fuels such as H 2 or reduced hydrocarbons from CO 2 . To improve these processes, it is necessary to expand the fundamental understanding of catalytically active species at low overpotential, which will further the development of electrocatalysts with high activity and durability. In this context, performing experimental investigations of the electrocatalysts under realistic working regimes, i.e. under operando conditions, is of crucial importance. Here, we study a highly active quinary transition metal oxide-based OER electrocatalyst by means of operando ambient pressure X-ray photoelectron spectroscopy and X-ray absorption spectroscopy performed at the solid/liquid interface. We observe that the catalyst undergoes a clear chemical-structural evolution as a function of the applied potential with Ni, Fe and Co oxyhydroxides comprising the active catalytic species. While CeO 2 is redox inactive under catalytic conditions, its influence on the redox processes of the transition metals boosts the catalytic activity at low overpotentials, introducing an important design principle for the optimization of electrocatalysts and tailoring of high performance materials.

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“…Modification using an additive, for instance oxides of antimony, may increase the conversion as a result of synergetic effects and/or the concentration of spillover oxygen [14]. The behavior of catalysts before and after the catalytic reaction has to be investigated by XRD, FT-IR, and ESR in order to give a conclusive and profound overview of the modification in the catalytic system.…”

Section: Resultsmentioning

confidence: 99%