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

被引：28
作者：
de Mattos, Flavia C. G. [1 ]
de Carvalho, Eduardo N. C. B. [1 ]
de Freitas, Elon F. [1 ]
Paiva, Mateus F. [1 ]
Ghesti, Grace F. [1 ]
de Macedo, Julio L. [1 ]
Dias, Silvia C. L. [1 ]
Dias, Jose A. [1 ]
机构：
[1] Univ Brasilia, Inst Quim, Lab Catalise, Campus Darcy Ribeiro,CP 4478, BR-70904970 Brasilia, DF, Brazil
来源：
JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY | 2017年 / 28卷 / 02期
关键词：
supported heteropolyacid; 12-tungstophosphoric acid; silica-alumina; ethanol; esterification of acetic acid with ethanol; LIQUID-PHASE ESTERIFICATION; HETEROPOLY ACIDS; ACETIC-ACID; REACTION-KINETICS; GAS-PHASE; H3PW12O40; CATALYST; SITES; NMR; IMMOBILIZATION;
D O I：
10.5935/0103-5053.20160183
中图分类号：
O6 [化学];
学科分类号：
0703 ;
摘要：
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 degrees C, temperature of 100 degrees C, 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 Bronsted weak-medium strength (pyridine desorption between 300 and 500 degrees C).
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页码：336 / +
页数：19
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