Multicomponent Oxides in Selective Oxidation of Alkanes Theoretical Acidity versus Selectivity

Abstract

Semi-empirical relationships between the 'optical basicity' K (so-called after Duffy) of solid oxides and the 'thermodynamic' selectivity in mild and total oxidation of hydrocarbons have recently been set up. They can be used to determine the optimum acidity of a solid catalyst or to account for its observed selectivity in a given reaction. The oxidic M x O z catalysts were ranked by means of the electron-donor power of oxygen which is represented by the optical basicity K. The difference of ionization potential I of molecules when the reactant becomes the product, which represents the variation of electron-donor power during the reaction, was used to rank reactions. Plotting DI against K for each 'reaction/selective catalyst' couple results in straight lines, the equation of which depends on the chemical nature of reactant (alkane and alkyl-aromatics, alkenes and aromatics, alcohols) and on the deepness of oxidation (ammoxidation, mild oxidation, total oxidation). The correlations are used to discuss the behaviour of V-and Mo-based, simple and multicomponent oxide catalysts, in the mild oxidation of C 2 and C 3 hydrocarbons.

Resource‐Efficient Alkane Selective Oxidation on New Crystalline Solids: Searching for Novel Catalyst Materials

“…The significantly higher activity of Zr(P 0.5 V 0.5 ) 2 O 7 in comparison to the pure vanadate is quite remarkable. We attribute this effect to the significantly lower nucleophilicity (optical basicity) of the mixed phosphate vanadate, which is in agreement with the reasoning of Bordes [13]. The high activity of the vanadium-substituted zirconium oxide phosphate (Cat-23 and Cat-24), which has even lower vanadium content, can be explained in a similar way.…”

“…The optical basicity K o of a catalyst material has been suggested to be correlated with its selectivity in mild oxidation catalysis of hydrocarbons [13,14]. According to this concept, put forward by Bordes-Richard and Courtine [13,14], the optical basicity of a solid should be one (out of several) descriptor(s) for its behavior as catalyst in the selective oxidation. Optical basicities calculated for the materials under investigation using the data given by Lebouteiller and Courtine [70] are in the range 0.…”

H2S Sensing by Hybrids Based on Nanocrystalline SnO2 Functionalized with Cu(II) Organometallic Complexes: The Role of the Ligand Platform

“…When detecting NH 3 (Lewis base) in dry air, the sensor signal correlates with the surface concentration of corresponding acid sites [ 39 , 40 ]. As Cu(II) is a weaker acid than Sn(IV) [ 41 ], its presence on the SnO 2 surface does not increase the sensitivity of the hybrid materials towards ammonia.…”

Catalytic Properties of Silver Vanadium Phosphates in n‐Butane Oxidation – Considerations on the Impact of the [VxOy] Substructure

“…The optical basicity has been suggested to be correlated with selectivity in mild oxidation catalysis of hydrocarbons [33,34]. The highly active and selective (VO) 2 P 2 O 7 catalyst has the optical basicity K = 0.49 [33].…”