Ganapati Shanbhag
Poornaprajna Institute of Scientific Research, India
Title: Novel metal hydroxystannates and their oxides as solid acid-base catalysts for biodiesel synthesis and glycerol transformations
Biography
Biography: Ganapati Shanbhag
Abstract
Increasing demand for petroleum fuels and depleting availability of crude oil has made to look for alternative sources of energy. Biodiesel is one such source which attracted many researchers since it can be synthesized by transesterification of vegetable oil in presence of an acid or a base catalyst. To overcome the issues related to homogeneous catalysts like NaOH, heterogeneous acid-base catalysts were developed to make an eco-friendly process of biodiesel synthesis. Further, to improve the economics of the process, the byproduct glycerol can be converted into value-added chemicals like acetins and glycerol carbonate via transesterification and carbonylation reactions respectively. In this work, a novel metal hydroxystannate was reported as a strong base catalyst for organic transformations. It has a perovskite type crystal structure with metal atoms octahedrally coordinated with corner sharing hydroxyl groups to form Sn(OH)6 and M(OH)6 octahedra (where M is Ca, Zn, Mg or Sr). It is found that calcium hydroxystannate acts as a strong solid base catalyst with very high activity for biodiesel synthesis from vegetable oils and synthesis of acetins from glycerol. On the other hand, zinc hydroxystannate acts as bifunctional acid-base catalyst with hydroxy groups contributing as basic sites and zinc as Lewis acid center. This catalyst was successfully applied for glycerol carbonylation with urea to make glycerol carbonate. Further, calcination of metal hydroxystanntes at high temperatures resulted in metal composite oxides which also found to exhibit good acidity and basicity which are successfully applied for glycerol transformation reactions.