Catalytic etherification of glycerol by tert-butyl alcohol to produce oxygenated additives for diesel fuel

The heterogeneous catalytic etherification of glycerol with tert-butyl alcohol was investigated in presence of lab-made silica supported acid catalysts. As reference, two commercial acid ion-exchange resins were also used. Experiments were carried out in batch mode at TR ranging from 303 to 363 K. An increase in reaction temperature favors the formation of di-substituted ethers. The etherification reaction proceeds according to a consecutive path and the surface reaction between adsorbed glycerol and protonated tert-butanol (tertiary carbocation) can be considered as the rate determining step. Steric hindrance phenomena and water hinder the formation of tri-substituted ether (TBGE). As expected, water removal was necessary to allow the higher ethers formation. The specific activity (turnover frequency, TOF) of A-15 catalyst is significantly higher than that of the other studied acid systems, due to the wide pore diameter that allows an easier accessibility of the reagent molecules.

The heterogeneous catalytic etherification of glycerol with tert-butyl alcohol in the presence of commercial and lab-made solid acid catalysts was investigated. Experiments were carried out in batch mode at TR ranging from 303 to 363 K. The influence of acid capacity, reaction temperature, pressure, and the presence of water on catalyst performance were investigated. Kinetic evaluations and reaction mechanism were also assessed.Figure optionsDownload as PowerPoint slide