Acidity and Characterization of 12-Tungstophosphoric Acid Supported on Silica-Alumina

AUTOR(ES)

Mattos, Flávia C. G. de, Carvalho, Eduardo N. C. B. de, Freitas, Elon F. de, Paiva, Mateus F., Ghesti, Grace F., Macedo, Julio L. de, Dias, Sílvia C. L., Dias, José A.

FONTE

J. Braz. Chem. Soc.

DATA DE PUBLICAÇÃO

2017-02

RESUMO

This work deals with preparation and characterization of H3PW12O40 (H3PW) supported on silica-alumina. Impregnation of H3PW (15, 20, 30 and 40 wt.%) on commercial silica-alumina support in acidic aqueous solution is effective for preparing this catalyst keeping its Keggin structure, according to different methods of characterization. The catalysts were tested in a model reaction of acetic acid with ethanol and 30 wt.% H3PW/SiO2-Al2O3 had the highest activity under the conditions: catalyst calcination at 300 ºC, temperature of 100 ºC, acetic acid:ethanol molar ratio of 2:1 and catalyst:acetic acid mass ratio of 10 wt.%. The reaction yield was 79 and 100% selectivity for ethyl acetate over three reutilizations, for reaction time of 2 h. The calculated total acid site distribution was 0.299 mmol g-1 (97% of the theoretical probed by pyridine), and most of these (0.236 mmol g-1) were Brønsted weak-medium strength (pyridine desorption between 300 and 500 ºC).

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