Role of vanadium in Keggin heteropoly molybdate supported on titania catalysts for oxidation reactions

Abstract

Vanadium-incorporated molybdophosporic acid catalysts supported on titania were prepared and characterized by FT-IR, X-ray diffraction and laser Raman spectroscopy. Characterization data reveals the incorporation of vanadium into the primary structure of Keggin ion of MPA. Catalysts activities were evaluated for oxidation of 1,2-benzenedimethanol using H 2 O 2 and O 2 as oxidants. Vanadium-containing catalysts showed high activity compared to their parent heteropoly acids. Oxidation ability depended on the number of V atoms present in Keggin heteropoly molybdate. Effect of reaction parameters on the oxidation ability was also evaluated.

Advances in Polyoxometalates as Electron Mediators for Photocatalytic Dye Degradation

“…Keggin-type polyanions [XM 12 O 40 ] n− (X = B, P, Si, Ge, As; M = W, Mo, V), as one of the fundamental polyanions, possess oxygen-rich surfaces and robust coordination capabilities [51]. Vanadium atoms establish connections with the framework through metal-oxygen bonds, giving rise to vanadium-terminated or vanadium-substituted structures, thereby enhancing the compositional and property diversity of Keggin-type POMs [52]. Fengrui Li et al [53] obtained a tri-vanadium-capped phosphomolybdate ([Na 3 PMo 12 V 3 O 43 ]•4H 2 O, denoted as PMo 12 V 3 ) through a hydrothermal reaction for the removal of MB.…”

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

“…[6,7] Keggin-type heteropolyoxometallates have been proven as efficient catalysts in many organic transformations such as hydrolysis, ringopening reactions of epoxides, Fridel-Crafts alkylation, acylation of esters, sulfonation nitration Oxidation reaction, Dakin-West reaction, aromatic halogenation, intramolecular rearrangement, hydroalkylation of olefins, isomerization etc. [3,[8][9][10][11] The restriction of HPA's is low thermal stability, low surface areas and problems associated with their separation from the reaction mixture due to homogeneous nature. To avoid this problem HPA's can be made eco-friendly insoluble acid catalysts with high thermal stability and high surface area by supporting them on suitable supports.…”

“…Keggin‐type heteropolyoxovanadates with the general formula of H 3+ x PM 12‐ x V x O 40 (where M= W, Mo and x=0, 1, 2, and 3) are known to exhibit interesting physical and chemical properties . Keggin‐type heteropolyoxometallates have been proven as efficient catalysts in many organic transformations such as hydrolysis, ring‐opening reactions of epoxides, Fridel‐Crafts alkylation, acylation of esters, sulfonation nitration Oxidation reaction, Dakin‐West reaction, aromatic halogenation, intramolecular rearrangement, hydroalkylation of olefins, isomerization etc . The restriction of HPA's is low thermal stability, low surface areas and problems associated with their separation from the reaction mixture due to homogeneous nature.…”

Synthesis, crystal structure and photochemistry of Hexakis(butan-1-aminium) heptamolybdate(VI) tetrahydrate

“…(NH 4 ) 4 [Li 2 (H 2 O) 7 ][Mo 7 O 24 ]•H 2 O (E 1/2 = −0.579 V)34 and (NH 4 ) 3[Li 3 (H 2 O) 4 (μ 6 -Mo7 O 24 )]•2H 2 O (E 1/2 = −0.537 V)34 unlike the differing conductivity data. The observation of identical redox response in aqueous solutions of 1 and 1a serves to confirm the transformation of the mixed mono-hepta 1a to a pure heptamolybdate 1.4.…”