Tuning Surface Modification of Potasium Boasted Phosphomolybdic Acid Catalysts for Selective Oxidative Esterification of Benzyl alcohol

A series of potasium boasted phosphomolybdic acid (PM) catalysts were successfully synthesized by ion-exchange method. These materials were characterized by BET surface area, FT-IR, XRD, Pyridine adsorbed FT-IR and TEM analysis to find the structural and nature of acidic sites of the catalyst. BET surface area result reveals that surface area significantly improved after K loadings compare to pure phosphomolybdic acid. XRD results provide crystallites of cubic Keggin ion were observed after K loading. FT-IR results provide characteristic Keggin ion bands were retained even after K loadings. TEM analysis reveals spherical morphology is maintained even after K loadings and KPM-2 catalyst exhibits smaller particle size than other K loadings. Pyridine adsorbed FT-IR spectra exhibits Brønsted to Lewis acidic sites ratio is higher in case of KPM-2 when compared to other K loadings. These synthesized K boasted PM materials were evaluated for oxidative esterification of benzyl alcohol to methyl benzoate possesses higher activity and selectivity during reaction than pure PM catalyst. Graphical Abstract Scheme 1: Selective oxidation of benzyl alcohol over potasium boasted phosphomolybdic acid catalyst