Acidity and characterization of 12-Tungstophosphoric acid supported on Silica-alumina

• Autor(a) principal: Mattos, Flávia Cardoso Genaro de
• Data de Publicação: 2017
• Outros Autores: Carvalho, Eduardo N. C. B. de, Freitas, Elon F. de, Paiva, Mateus F., Ghesti, Grace Ferreira, Macedo, Julio Lemos de, Dias, Sílvia Cláudia Loureiro, Dias, José Alves
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UnB
• Texto Completo: http://repositorio.unb.br/handle/10482/30690; http://dx.doi.org/10.5935/0103-5053.20160183
• topic: Sílica-alumina; Álcool; Esterificação

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).