Phosphotungstic Wells-Dawson Heteropolyacid as Potential Catalyst in the Transesterification of Waste Cooking Oil

The esterification of oleic acid was applied in order to screen the suitability a series phosphotungstic-based Wells-Dawson types compounds as potential catalysts heterogeneous transesterification sunflower waste cooking oil. This test reaction indicated that phosphotungstic heteropolyacid H6P2W18O62·xH2O, dispersed on titania oxide loading 15 mg per m2 support (named 42% HPA/TiO2) and possessing exclusively Brønsted sites, most promising among screened materials. In addition, application nonlinear analysis methodology find surface fits specific activity with methanol at various temperatures, weights catalyst, molar ratios substrates, stirring speeds, also considering active phase desorption out catalyst’s surface, allowed determining optimum operative conditions were oil afterwards. 60 °C 1:9 WCO: ratio batch reactor under 650 rpm for 3 h, catalyzed 0.25 wt% HPA/TiO2 (20.0 g 49.6 catalyst), presents 74.6% conversion glycerides 74.4% yield towards fatty methyl esters. catalyst recovered reused several times, maintaining fairly constant catalytic performance.