Physicochemical properties of vanadium impregnated Al-PILCs: Effect of vanadium source

Summary Clay from the Middle Anatolian previously pillared by Al 13 -Keggin ions and then calcined at 300 °C (Al-PILC) was impregnated with aqueous solutions of vanadium precursors by impregnation from solution (I), wet impregnation (WI) and washing after wet impregnation (WWI) methods. The crystal and textural properties were evaluated by X-ray powder diffraction (XRD), nitrogen sorption and transmission electron microscopy (TEM) images. Vanadium incorporation into the Al-PILC resulted decreases in the basal spacing from 1.75 nm to 1.35 nm with the preserved typical layered structure. The use of sodium metavanadate (NaVO 3 ) as the source and the impregnation from solution as the incorporation method resulted in less structural deformation in the final solid. Loading of the vanadyl sulfate hydrate (VOSO 4 ·H 2 O) resulted in a higher V/Si ratio in the solid since both settling and ion exchange mechanism occured. The vanadium was usually bonded in the +5 oxide form, and the particles were settled between these layers and onto the outer surface of the clay particles. The existence of V–O structural bonds and Bronsted and Lewis acid sites were observed in the Fourier transform infrared spectroscopy (FTIR) results. Up to 300 °C dehydration with high mass loss was observed, followed by the decreases in mass loss, and finally, at around 900 °C, hydroxylation reactions were observed in the TGA/DTA analyses.