The selective conversion of furfuryl alcohol to ethyl levulinate over Zr-modified tungstophosphoric acid supported on β-zeolites

Catalysts of zirconium-exchanged proton-containing tungstophosphoric acid (TPA) supported on beta-zeolites were prepared by an impregnation method for the selective alcoholysis of furfuryl alcohol into ethyl levulinate. The prepared catalysts were characterized by different spectroscopic techniques. The results indicated the existence of a Keggin ion structure of TPA after its modification with Zr ions and successive dispersion on beta-zeolites. The introduction of Zr in TPA generated Lewis acidic sites in the catalyst. Pyridine-adsorbed FT-IR confirmed the presence of both Bronsted and Lewis acidic sites in catalysts. The catalytic activity for the alcoholysis of furfuryl alcohol depends on the strength of both Bronsted and Lewis acids of the catalyst. Among these catalysts, 20%Zr(0.75)TPA/beta-zeolite was active for the alcoholysis of furfuryl alcohol with a 96% yield of ethyl levulinate. Optimal conditions were established to obtain maximum yield. A plausible reaction mechanism was also proposed. The catalyst was reused without any appreciable loss of activity.

Automated summary

Catalysts based on zirconium-exchanged proton-containing tungstophosphoric acid supported on beta-zeolites were prepared and characterized for the selective alcoholysis of furfuryl alcohol into ethyl levulinate. The catalysts exhibited both Lewis and Bronsted acidic sites, and 20%Zr(0.75)TPA/beta-zeolite catalyst showed a high activity with a 96% yield of ethyl levulinate in the alcoholysis reaction. The catalyst could be reused without significant loss of activity.