Role of oxide catalysts basicity in selective oxidation

Mamedov, É. A.; Vislovskii, V. P.; Талышинский, Р. М.; Rizayev, R. G.

doi:10.1016/s0167-2991(08)61687-0

Cited by 7 publications

(3 citation statements)

References 4 publications

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“…If lattice oxygen is electrophilic, it will lead to total combustion of an olefin or aromatic hydrocarbon, whereas if it is nucleophilic enough, a selective mild oxidation will result (30). For example, Mamedov et al have shown the influence of the nucleophilic character of lattice oxygens on the catalytic properties of various mixed oxides in the propylene allylic oxidation (31). This is why optical basicity, characterizing the capacity of oxygen to give a part of its negative charge, seems to be an interesting parameter and one which could predict the ability of an oxide to catalyze a given reaction.…”

Section: Application Of Optical Basicity To Selective Oxidationmentioning

confidence: 99%

Improvement of a Bulk Optical Basicity Table for Oxidic Systems

Lebouteiller

Courtine

1998

Journal of Solid State Chemistry

115

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Section: Application Of Optical Basicity To Selective Oxidationmentioning

confidence: 99%

Improvement of a Bulk Optical Basicity Table for Oxidic Systems

Lebouteiller

Courtine

1998

Journal of Solid State Chemistry

115

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“…Both homolytic bond cleavage leading to a propyl radical and heterolytic splitting have been considered . The latter proposal has been associated with the involvement of nucleophilic oxygen species such as V=O entities, and the beneficial influence of basicity promoted by alkali doping has been reported . However, the nature of the oxygen species involved in the proton abstraction remained scarcely discussed.…”

Section: Introductionmentioning

confidence: 99%

Activation of C−H Bond of Propane by Strong Basic Sites Generated by Bulk Proton Conduction on V‐Modified Hydroxyapatites for the Formation of Propene.

et al. 2020

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Insights into the catalytic transformation of propane to propene on V-apatite catalysts are provided based on structure-reactivity relationships. Substitution of phosphates by vanadates in the hydroxyapatite structure leads to the formation of Ca 10 (PO 4 ) 6-x (VO 4 ) x (OH) 2-y O y V-oxy-hydroxy-apatite solid solutions (x = 0!6). Bulk vanadium incorporation promotes (i) calcium rich terminations (XPS, CO adsorption), (ii) proton deficiency inside the OH À channels ( 1 H NMR) giving rise to O 2À native species, (iii) the thermally-activated formation of additional O 2À species along the OH À channels resulting in H-bonding interaction (in situ DRIFT) and (iv) the proton conduction process that eventually results in the surface exposure of O 2À species (in situ impedance spectroscopy). The exposure of Ca 2 + À O 2À surface acid-base pairs allows the dissociation of hydrogen, emphasizing the strong basicity of the related O 2À species. Whereas an increasing vanadium content is beneficial to propene selectivity, it scarcely impacts propane conversion. The reaction proceeds mainly upon oxidative dehydrogenation, even if the minor dehydrogenation route is also observed. Surface O 2À generated thanks to proton mobility are involved in the CÀ H bond activation, as shown by the synergistic effect between the oxidative dehydrogenation of propane reaction and the bulk proton conduction measured under operando conditions. This puts emphasis on the key role of strong basic sites for propane activation.the temperature was cooled down to 673 K and the conductivity set-up was fed with the reacting feed. The H + ion-conductivity of the working catalyst was measured after 2 hours on stream at 673, 723 and 773 K.

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“…This raises the question of the nature of the active site able to activate light alkane over metal modified hydroxyapatite. Given that the limiting step is H abstraction, a beneficial influence of basicity on the activation process was proposed [84,87,96,111,112]. It is well supported by the established relationships between the alkane conversion and basic reactivity probed by model reactions [10].…”

Section: Activation Site and Mechanismmentioning

confidence: 94%

Aerobic Selective Oxidation of Alcohols and Alkanes overHydroxyapatite‐BasedCatalysts

Costentin

Launay

2022

Design and Applications of Hydroxyapatite‐Based Catalysts

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Selective oxidation catalysis is of prime importance for the production of many key intermediates. The control of selectivity in the presence of gaseous oxygen is quite challenging and requires the development of efficient catalysts. Thanks to their large composition range, resulting from the modulation of their stoichiometry and substitution ability, hydroxyapatites can be modified by many metals which make them original catalytic systems gathering both tunable acid-base properties and redox properties. In this chapter, we will show the interest of metal modified hydroxyapatite catalysts for various classes of oxidation reactions. Due to their large range of stability, they can be implemented either in liquid phase for aerobic oxidation of alcohols (Pd, Ru), or at very high temperature (> 600°C) for gas phase alkane oxidation, partial oxidation of methane (Rh, Ni) and oxidative dehydrogenation of other alkanes (V, Co…). The influence of the metal incorporation method (ion exchange, impregnation in excess of solution, or coprecipitation) on the metal dispersion and catalytic performance will be discussed. Finally, the role of the basic properties of hydroxyapatites in the alkane activation will be discussed.

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Role of oxide catalysts basicity in selective oxidation

Cited by 7 publications

References 4 publications

Improvement of a Bulk Optical Basicity Table for Oxidic Systems

Improvement of a Bulk Optical Basicity Table for Oxidic Systems

Activation of C−H Bond of Propane by Strong Basic Sites Generated by Bulk Proton Conduction on V‐Modified Hydroxyapatites for the Formation of Propene.

Aerobic Selective Oxidation of Alcohols and Alkanes overHydroxyapatite‐BasedCatalysts

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