Preparation, Characterization and Reactivity of Keggin Type Phosphomolybdates, H3−2x Ni x PMo12O40 and (NH4)3−2x Ni x PMo12O40, for Adipic Acid Synthesis

Abstract

Two H3−2x Ni x PMo12O40 and (NH4)3−2x Ni x PMo12O40 Keggin type heteroploysalts series (x: 0.25–1.5) were synthesized and characterized by IR spectroscopy, XR diffraction and thermal analysis (TG). Their catalytic properties were studied in the oxidation reaction of cylohexanone and cyclohexanone/cyclohexanol mixture to adipic acid in presence of hydrogen peroxide and in absence of solvent. The effects of catalyst/substrate molar ratios and heteropolysalt composition on AA yields were examined. TG analysis allowed to confirm the x value. Obtained catalytic results showed that both salts series are efficient for oxidation of cylohexanone and cyclohexanone/cyclohexanol mixture. Adipic acid yield achieved 45 % in the cyclohexanone oxidation in presence of (NH4)0.5Ni1.25PMo12O40 with a catalyst/substrate molar ratio of 10−3.