Design of a functionalized lacunary polyoxometalate catalyst for efficient epoxide ring-opening and biodiesel production.

Developing robust and efficient heterogeneous catalysts remains a key challenge in catalytic organic transformations. In this work, a lacunary polyoxometalate-based catalyst (LPOM) was synthesized and subsequently functionalized with 3-(aminopropyl)trimethoxysilane (APTMS) and then 1,3-propanesultone (1,3-PS) to achieve LPOM/APTMS/1,3-PS. Comprehensive characterization using various physicochemical techniques confirmed the successful modification of the lacunary POM framework with desired functional groups. The catalytic behavior of the prepared material was assessed through two representative transformations: the ring-opening of styrene oxide and the esterification of oleic acid with methanol toward biodiesel synthesis. The catalyst demonstrated remarkable efficiency, delivering 99% conversion of styrene oxide within 10 min and 98% oleic acid conversion within 2 h. Moreover, it maintained excellent structural integrity and catalytic efficiency over four consecutive cycles. These findings demonstrate the potential of LPOM/APTMS/1,3-PS as a stable, highly efficient, and environmentally benign catalyst for sustainable organic transformations and biofuel synthesis.