Tetrabutyl Ammonium Salts of Keggin-Type Vanadium-Substituted Phosphomolybdates and Phosphotungstates for Selective Aerobic Catalytic Oxidation of Benzyl Alcohol

A series of tetrabutyl ammonium (TBA) salts V-included Keggin-type polyoxoanions with W (TBA4PW11V1O40 and TBA5PW10V2O40) Mo (TBA4PMo11V1O40 TBA5PMo10V2O40) as addenda atoms were prepared using a hydrothermal method. These synthesized materials characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance (DRS UV-Vis), thermogravimetric analysis (TGA), CHN elemental (EA), inductively coupled plasma spectrometry (ICP-MS), N2 physisorption techniques to assess their physicochemical/textural properties correlate them catalytic performances. According FT-IR DRS UV-Vis, (PVXW(Mo)12?XO40)(3+X)? anions are the main species present in TBA salts. Additionally, CHN-EA ICP-MS revealed that desired stoichiometry was obtained. Their activities liquid-phase aerobic oxidation benzyl alcohol benzaldehyde studied at 5 bar O2 170 °C. Independently atom nature, activity increased number V Keggin anion structure. For both catalysts, polyoxometalates highest V-substitution degree (TBA5PMo10V2O40 showed higher activity. The maximum conversions obtained 93% 97% (TBA)5PMo10V2O40 (TBA)5PW10V2O40 respectively. In all cases, selectivity toward than 99%.