Synthesis of oxygenated compounds for fuel formulation: Etherification of glycerol with ethanol over sulfonic modified catalysts

Abstract

The present study is focused on the etherification of glycerol with anhydrous ethanol over arenesulfonic acid-functionalized mesostructured silicas to produce ethyl ethers of glycerol that can be used as gasoline or diesel fuel components. Within the studied range, the best conditions to maximize glycerol conversion and yield towards ethyl-glycerols are: T = 200ºC, ethanol/glycerol molar ratio = 15/1, and catalyst loading = 19 wt.%. Under these reaction conditions, 74% glycerol conversion and 42% yield to ethyl ethers have been achieved after 4 h of reaction but with a significant presence of glycerol by-products. In contrast, lower reaction temperatures (T=160ºC) and moderate catalyst loading (14 wt.%) in presence of a high ethanol concentration (ethanol/glycerol molar ratio = 15/1) are necessary to avoid the formation of glycerol by-products and maximize ethyl-glycerols selectivity. Interestingly, a close catalytic performance to that achieved using high purity glycerol has been obtained with low-grade water-containing glycerol.