Selective conversion of furfuryl alcohol into butyl levulinate over zinc exchanged heteropoly tungstate supported on niobia catalysts

Abstract

Selective synthesis of butyl levulinate by alcoholysis of furfuryl alcohol with n-butanol was achieved over of zinc exchanged tungstophosphoric acid supported on niobia catalysts. These catalysts were prepared and characterized by powder X-ray diffraction, FT-Infra red spectroscopy, pyridine adsorbed-FT-IR, temperature programmed desorption of ammonia, Laser Raman spectroscopy. The characterization results confirmed that the primary structure of Keggin ion of tungstophosphoric acid remained intact after exchange of its protons with zinc and subsequent dispersion on niobia. The exchange of Zn ions with the protons of heteropoly tungstate resulted in the creation of Lewis acidic sites. The catalysts were active for the synthesis of butyl levulinates under mild conditions within short reaction time. The activity of the catalysts related to the acidity of the catalysts which was dependent on the amount of Zn exchanged to the heteropoly tungstate on niobia. Reaction conditions were optimized and about 94% yield of n-butyl levulinate was achieved. The catalysts are reusable without any appreciable loss in activity.