Comparative study on catalytic dehydration of glycerol with alcohols

Abstract

A comparative study of glycerol dehydration with alcohols (methanol, ethanol, tert-butyl alcohol) over ion exchange resin Amberlyst-35 was performed. The effect of catalyst amounts (1-15 wt.% to glycerol), reaction temperature (50-100 °C), reaction time (5-10 h), and the molar ratio of alcohols to glycerol (3:1-8:1) were carried out in 50 mL stainless steel autoclave. During the process of glycerol dehydration with alcohols, when the catalyst amount (wt.% to glycerol) is over 10%, it was observed that neither glycerol conversion nor product selectivities are changed significantly. The optimum molar ratios of glycerol to methanol, ethanol and tert-butyl alcohol were 1:6, 1:4, and 1:6, respectively. The appropriate reaction temperature and reaction time were 80 °C and 8 h at which the selectivities of di-alkyl glycerol ethers and tri-alkyl glycerol ether arrive to the highest. However, the main product was mono-alkyl glycerol ether (MAGE) in glycerol dehydration with tert-butyl alcohol due to steric hindrance influence. If MAGE is considered as the target product, the glycerol dehydration with tert-butyl alcohol could be a good choice. Additionally, the glycerol dehydration with ethanol could be a better route converting biomass material into vehicle fuel in view of its desired yields of higher ethers.