Heteropolyacid (H3PW12O40)-impregnated mesoporous KIT-6 catalyst for green synthesis of bio-diesel using transesterification of non-edible neem oil

Abstract

Mesoporous Ia3d cubic structured KIT-6 support was prepared by hydrothermal strategy and heteropoly acid content (10, 20 and 30%) was stacked on KIT-6 by wet-impregnation technique. The synthesized catalysts were characterized by XRD, N2-sorption, NH3-TPD, ATFT-IR, TEM and SEM–EDAX analyses. Acid properties of the supported catalysts were investigated by pyridine-adsorbed ATFT-IR and NH3-TPD, respectively. Poly-anion coordination present in the catalyst was confirmed by the DRS-UV spectrum. The dispersion of heteropoly acid on the catalyst surface was observed by TEM analysis. Also, the presence of the elements such as W and P on the catalyst and its morphology were represented by the HRSEM–EDAX technique. The catalytic activity of HPWA/KIT-6 was investigated by the transesterification of neem oil with methanol. Among the different wt% catalyst, 20% catalyst showed highest neem oil conversion and selectivity at an optimized reaction temperature of 60 °C. Further, the spent catalyst was recovered and recycled three times, and it showed activity losses of less than 4%.