Biomass conversion to diesel via the etherification of furanyl alcohols catalyzed by Amberlyst-15

The etherification of furanyl alcohols produced from biomass-derived glucose and fructose has been a growing area of research for production of alternative diesel additives. We have determined that the Brønsted acidic resin catalyst, Amberlyst-15, is highly active and selective for the etherification of furanyl alcohols by both ethanol and butanol. The mechanism and kinetics of this reaction were investigated using 5-methylfurfuryl alcohol (MFA) as a probe molecule. Etherification of MFA was found to be first order in both the concentrations of furanyl alcohol and the acid sites. The mechanism of MFA etherification also holds for the etherification of 2,5-bis(hydroxymethyl)furan (BHMF) and 5-(hydroxymethyl)furfural (HMF). In the case of HMF, we find that acetalization of HMF precedes etherification in alcohol solutions. The apparent activation energy of furanyl alcohol etherification in ethanol and butanol solutions ranged from 17.0 to 26.3 kcal/mol. Electron donation/withdrawal at the 2 or 5 position of the furan ring in addition to solvent polarity was found to have significant effects on the rate of furanyl alcohol etherification.