Design and Catalytic Applications of 1D tubular nanostructures: Improving Efficiency in Glycerol Conversion

The design of novel and efficient heterogeneous catalysts represents one of the main challenges in the development of sustainable processes. A straightforward one-pot sol-gel approach for the controlled preparation of highly active 1D nanotubes is herein presented. The optimization of the synthesis parameters allowed obtaining materials with tubular structure and very high surface area even in the absence of additional hydrothermal treatments hence further reducing the environmental impact of the synthesis approach. The isomorphic substitution of Sn within the silica framework was assessed via 119Sn solid state NMR under static conditions. Sn-silica nanotubes were efficiently used to catalyze both the transformation of dihydroxyacetone into ethyl lactate and the conversion of glycerol into solketal, where outstanding turnover frequencies were obtained under solvent-free conditions. The catalytic performance of these materials is ascribed to the enhanced accessibility of their active sites given by their tubular morphology and to the suitable combination of acid sites. Moreover, no-leaching of active sites was evidenced and the best solid preserved its activity in multiple catalytic cycles. Characterization after the reuses allows supporting further the stability of tin-nanotubes under the selected reactions conditions.