Synthesis, characterization and catalytic performance of a novel picolinic acid-12-molybdophosphoric acid hybrid catalyst

Abstract

A novel 12-molybdophosphoric acid (HPM)-based complex (H2 PI)2(H 3 O)[PMo12O 40] [Mo2 O5 (H2 O)2 (PI)2 ]•11H2 O (PI-HPM) was prepared by modification with picolinic acid (HPI) and characterized by the methods of Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG), X-ray powder and single crystal diffraction. The complex retained the classical Keggin structure of bulk HPM, there were some strong hydrogen bonds existing between the [PMo12 O40 ]3- polyanion, the [Mo2 O5 (H2 O)2 (PI)2 ] coordination moiety, the protonated HPI and the lattice water molecules. Then PI-HPM was employed as heterogeneous catalyst for esterification reaction to evaluate its acid-catalytic activity. The complex exhibited high activity and good durability in reaction mixtures, indicating that it was a promising heterogeneous acid catalyst for esterification that including the conversion of oleic acid to oleates.