Tert-Butylation of glycerol catalysed by ion-exchange resins

Abstract

The etherification of glycerol with isobutylene or tert-butyl alcohol without solvent in the liquid phase catalysed by strong acid ion-exchange resins of Amberlyst type and by two large-pore zeolites H-Y and H-Beta was studied. The swelling of commercial macroreticular and gelular ion-exchange resins (Amberlysts) and its influence on glycerol tert-butylation is discussed in this work. By comparing the conversions of glycerol and selectivity to glycerol di- and tri- tert-butyl ethers for macroreticular and gel type ion-exchange resins, it can be concluded that acid macroreticular resins in dry form are very active catalysts for etherification reaction with isobutylene because of large pore diameter. tert-Butyl alcohol as alkylation agent is not suitable because formed reaction water deactivates the catalysts. The zeolites and gel type polymer catalysts are not effective for this etherification reaction (small pore diameter). The best results of glycerol tert-butylation by isobutylene at 100% conversion of glycerol with selectivity to di- and tri-ethers larger than 92% were obtained over strong acid macroreticular ion-exchange resins. Di- and tri- tert-butyl ethers of glycerol are potential oxygenates to diesel fuel.