Valorization of biomass derivatives: Keggin heteropolyacids supported on titania as catalysts in the suitable synthesis of 2-phenoxyethyl-2-furoate.

ANGELICA ESCOBAR; JULIAN ANDRES RENGIFO-HERRERA; PIERRE FLORIAN; MIRTA BLANCO; GUSTAVO P. ROMANELLI; LUIS R. PIZZIO

JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 425 p. 266 - 274

1381-1169

Titania modified by tungstophosphoric (TPA) and tungstosilicic (TSA) acid (30% w/w) were synthe-sized by the sol-gel method, using urea as low cost pore-forming agent and annealing at 500◦C for2 h (TiO2/TPA and TiO2/TSA respectively). The obtained materials were characterized by31P,29Si,1Hnuclear magnetic resonance (31P,29Si,1H MAS-NMR), X-ray diffraction (XRD), X-ray photo-electronspectroscopy (XPS), Raman spectroscopy (FT-Raman), acid strength by potentiometric titration with n-butylamine. Mesoporous materials were obtained, without important microporosity, as determined fromN2adsorption-desorption isotherms by the Brunauer-Emmett-Teller (BET) method. The XRD patterns ofthe modified samples exhibited only peaks of anatase phase. According31P/29Si MAS-NMR and XPS stud-ies, the main species present in the TiO2/TPA and TiO2/TSA samples are the Keggin anions by formingsurface acid species, and probably surface complex between Keggin anion and titania as well. Solids wereevaluated in the synthesis of 2-phenoxyethyl-2-furoate, by esterification of 2-furoic acid, a valuable prod-uct which can be obtained from biomass, with 2-phenoxyethanol, where TiO2/TPA sample showed thehighest catalytic activity. The reaction temperature, molar ratio acid:alcohol and catalyst amount werestudied as variables using TiO2/TPA sample. Results of catalytic activity and diffuse reflectance infraredFourier transform spectroscopy (DRIFT-FT-IR) measurements suggested that the reaction mechanismmay involve a protonated intermediate of 2-furoic acid polarizing the C O bond of the acid, and leavingthat can be easily attacked by 2-phenoxyethanol.