Etherification of glycerol with tert-butyl alcohol over sulfonated hybrid silicas

Abstract

The etherification of glycerol with tert-butyl alcohol has been carried out in the liquid-phase on different sulfonic acid functionalized hybrid silicas obtained by oxidative cleavage of tetrasulfide bridges. These materials exhibited different textural properties and acidities ranging from 0.5 to 2.3mmolg−1. First of all, different experimental variables, including the reactant ratio and temperature have been tested and all catalysts were essayed under optimal conditions. The best catalytic behavior of the hybrid silicas was obtained on S50TS50O (Yh-GTBE=28%) at 75°C and autogenous pressure. In fact, the glycerol conversion obtained on S50TS50O, clearly surpassed that obtained on A-15 (74 and 51%, respectively). The acidity and the hydrophilic character of the sulfonated hybrid silicas solids have been found to be key parameters for their catalytic activity whereas the surface area and porosity do not seem to be advantageous for this reaction. All catalysts were reused and subjected to an extensive characterization.