Artículos de revistas
Valorization of biomass derivatives: Keggin heteropolyacids supported on titania as catalysts in the suitable synthesis of 2-phenoxyethyl-2-furoate
Fecha
2016-12Registro en:
Escobar Caicedo, Angélica María; Rengifo Herrera, Julian Andres; Florian, Pierre; Blanco, Mirta Noemi; Romanelli, Gustavo Pablo; et al.; Valorization of biomass derivatives: Keggin heteropolyacids supported on titania as catalysts in the suitable synthesis of 2-phenoxyethyl-2-furoate; Elsevier Science; Journal of Molecular Catalysis A: Chemical; 425; 12-2016; 266-274
1381-1169
CONICET Digital
CONICET
Autor
Escobar Caicedo, Angélica María
Rengifo Herrera, Julian Andres
Florian, Pierre
Blanco, Mirta Noemi
Romanelli, Gustavo Pablo
Pizzio, Luis Rene
Resumen
Titania modified by tungstophosphoric (TPA) and tungstosilicic (TSA) acid (30% w/w) were synthesized by the sol-gel method, using urea as low cost pore-forming agent and annealing at 500 °C for 2 h (TiO2/TPA and TiO2/TSA respectively). The obtained materials were characterized by 31P, 29Si, 1H nuclear magnetic resonance (31P, 29Si, 1H MAS-NMR), X-ray diffraction (XRD), X-ray photo-electron spectroscopy (XPS), Raman spectroscopy (FT-Raman), acid strength by potentiometric titration with n-butylamine. Mesoporous materials were obtained, without important microporosity, as determined from N2 adsorption-desorption isotherms by the Brunauer-Emmett-Teller (BET) method. The XRD patterns of the modified samples exhibited only peaks of anatase phase. According 31P/29Si MAS-NMR and XPS studies, the main species present in the TiO2/TPA and TiO2/TSA samples are the Keggin anions by forming surface acid species, and probably surface complex between Keggin anion and titania as well. Solids were evaluated in the synthesis of 2-phenoxyethyl-2-furoate, by esterification of 2-furoic acid, a valuable product which can be obtained from biomass, with 2-phenoxyethanol, where TiO2/TPA sample showed the highest catalytic activity. The reaction temperature, molar ratio acid:alcohol and catalyst amount were studied as variables using TiO2/TPA sample. Results of catalytic activity and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT-FT-IR) measurements suggested that the reaction mechanism may involve a protonated intermediate of 2-furoic acid polarizing the C[dbnd]O bond of the acid, and leaving that can be easily attacked by 2-phenoxyethanol.