Study of catalysts comprising zirconium sulfate supported on a mesoporous molecular sieve HMS for esterification of fatty acids under solvent-free condition

New solid acid catalysts consisting of zirconium sulfate (ZS) supported on a pure hexagonal mesoporous material (HMS) have been prepared and characterized. ZS is intact on the HMS surface and form finely dispersed species. No ZS crystal phase was developed even at ZS loadings as high as 40 wt%. The interaction of ZS with the HMS material enhances the acidity and the catalytic activity of this reaction. The effects of ZS loading on structure, acidity and catalytic activity were closely monitored. The HMS-supported ZS catalyst exhibits higher catalytic activity than bulk ZS and various solid acid catalysts in liquid-phase esterification of oleic acid with n-butanol under solvent-free conditions. It is assumed that the reaction occurred mainly inside the mesopores of HMS. The reaction was found to obey Eley-Rideal (ER) mechanisms. The HMS-supported ZS is a promising solid acid catalyst for acid-type reactions, which involve large organic molecules such as fatty acids. (C) 2008 Elsevier B.V. All rights reserved.