Structural and acidity analysis of heteropolyacids supported on faujasite zeolite and its effect in the esterification of oleic acid and n-butanol

• 12%HPW/Zeolite Y is effective to catalyze esterification of oleic acid and n-butanol. • 12%HSiW/Zeolite Y is a good catalyst to esterification of oleic acid and n-butanol. • 12%HPW/Zeolite Y has 100% selectivity and 98% conversion for butyl oleate. • The catalysts were stable up to three cycles keeping about the same conversion. • Treatment at 200°C/4 h was efficient to recover the catalysts after each cycle. Abstract Most of the supporting catalytic materials seek to improve classical chemical processes that are less environment-friendly. The association of heteropolyacids (HPA) and zeolites has shown to be interesting for heterogeneous catalysis. In the present study, zeolite Y (faujasite) was modified by the incipient insertion of 12-tungstophosphoric (HPW) and 12-tungstosilicic (HSiW) acids for application in the esterification reaction of oleic acid with n-butanol. The fine chemical product (butyl oleate) is used in a variety of applications (e.g., plasticizers, lubricants). The catalysts (x%HPA/Y; x = 3, 6 and 12%) were characterized by EDXRF, XRD, FT-IR, multinuclear MAS NMR ( 27 Al, 29 Si, and 31 P), SEM, low temperature N 2 physisorption, thermal methods (TG/DTG), pyridine (Py) gas desorption (Py-TPD) and microcalorimetry of Py adsorption in liquid phase. The resulting acid composites showed advantages over both pristine solids with adequate nature, dispersion, stability, accessibility, and strength of active sites. High oleic acid conversions (70% for 12%HSiW/Y and 96% for 12%HPW/Y) with 100% selectivity to butyl oleate were obtained under these conditions: acid: alcohol ratio 1:2; 0.2 g of catalyst; 100°C and 1 h reaction. No leaching of the active phases was detected, and the best catalysts were used three times, keeping fair their initial conversion.