H6GeMo10V2O40•16H2O nanoparticles prepared by hydrothermal method: a new and reusable heteropoly acid catalyst for highly efficient acetylation of alcohols and phenols under solvent-free conditions

Direct catalytic synthesis of ε-caprolactam from cyclohexanol using [n-C16H33N (CH3)3]H2PW12O40 as a catalyst

“…The order of softness of heteropoly anions in aqueous solution was estimated as follows: PW 12 . The softness of heteropoly anions is assumed to play an important role in stabilizing organic intermediates [28]. It is known that the stabilization of organic intermediates is closely relative to the performance of the catalyst, which accounts for the lower conversion of cyclohexanol for CTAPMo than that for CTAH 2 PW.…”

“…The diffraction peaks at 2θ (in degree) = 8-11°,18-22°, 24-30°and 33-40°are characteristic of HPA anions with Keggin structure [28,29]. The average particle size was calculated by X-ray diffraction line broadening using the Debye-Scherrer equation.…”

Synthesis and Characterization of H3PW12O40 and H3PMo12O40 Nanoparticles by a Simple Method

“…Several methods have been reported for the synthesis of HPAs nanoparticles; these methods include Microemulsion [26], solid state [27], hydrothermal [28] and surfactant template method [29][30][31]. Although these methods are valuable, however, many of these procedures have significant drawbacks such as using of surfactant and other chemical reagent, long reaction times and poly-dispersity of particle size.…”

Quaternary Vanado‐Molybdotungstophosphoric Acid [H5PW6Mo4V2O40] Over Natural Montmorillonite as a Heterogeneous Catalyst for the Synthesis 4H‐Pyran and Polyhydroquinoline Derivatives

“…[2,21] Mixed-addenda HPA research is even more extensive since Keggin type derivatives can give rise to a greater number of stoichiometries, shapes, and aggregates. [6,22] The addenda W, Mo, and V and the main group heteroatoms P and Si are the most usual metal have been incorporated into the POM framework. [23] Most of the studies have examined on binary or ternary Keggin type heteropoly acids in several literature such as H 3 PW 12 O 40 , [24] H 3 PMo 12 O 40 , [25] H 4 PW 11 VO 40 , [26] H 4 PMo 11 V 1 O 40, [5] H 4 SiW 12 O 40 , [27] H 4 SiMo 12 O 40 , [28] and H 7 SiW 9 V 3 O 40 , [29] etc.…”

“…For example, the improvement in the catalytic activity of polyanions is closely related to addenda substitution . Mixed‐addenda HPA research is even more extensive since Keggin type derivatives can give rise to a greater number of stoichiometries, shapes, and aggregates . The addenda W, Mo, and V and the main group heteroatoms P and Si are the most usual metal have been incorporated into the POM framework .…”