H3PW12O40 immobilized on silylated palygorskite and catalytic activity in esterification reactions

The surface of acid-activated palygorskite (Pa) was modified by grafting 3-aminopropyltriethoxysilane (APTES) (the silylated Pa denoted PaAPTES) for immobilization of phosphotungstic acid (H3PW12O40, HPW). The samples were characterized by Fourier transform infrared spectroscopy (FTIR), N2 adsorption–desorption, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS). The catalytic activity was tested for the esterification of n-butanol with acetic acid. Both HPW/PaAPTES and HPW/Pa showed high and specific catalytic activity on the first use. Repeated use, decreased the catalytic activity of HPW/PaAPTES slowly, that of HPW/Pa strongly. Due to its unique properties, low cost and ready availability, HPW/PaAPTES provides a satisfactory option for catalyzing esterification reactions.