Green etherification of bioglycerol with 1-phenyl ethanol over supported heteropolyacid

Escalating demand for biodiesel production has generated surplus glycerol. Therefore, the consumption of glycerol for valuable conversions has become a global challenge. In an effort to convert glycerol, we have etherified it to make a biologically active component, 3-(1-phenylethoxy) propane-1,2-diol. Etherification of glycerol with 1-phenyl ethanol was carried out by using heterogeneous acid catalysts. The process is green and clean. Different types of heteropolyacids (HPAs) supported on hexagonal mesoporous silica (HMS) and K-10 clay were prepared by incipient-wetness technique and screened to get high selectivity towards monoether of glycerol. 20% w/w dodeca-tungstophosphoric acid (DTP)/HMS was found to be the best. The effects of various reaction parameters such as speed of agitation, catalyst loading, mole ratio of reactants and temperature were evaluated systematically to prove that the reaction obeys Langmuir-Hinshelwood-Hougen-Watson (LHHW) type of mechanism. It was also observed that the reaction was free from any external mass transfer as well as intra-particle diffusion limitations and was intrinsically kinetically controlled. An overall second order kinetic equation was used to fit the experimental data, under the assumption that all the species are weakly adsorbed on the catalytic sites. Apparent activation energy was estimated as 27.0 kcal/mol. Solvent-free condition for this reaction has also added the green chemistry perception to the reaction.