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Química Nova

versão impressa ISSN 0100-4042

Resumo

SCROCCARO, Karine Isabel et al. Impregnation of 12-tungstophosphoric acid on silica - part II: effect of different solvents on the impregnation and catalytic activity in methyl esterification of stearic acid. Quím. Nova [online]. 2014, vol.37, n.2, pp.232-237. ISSN 0100-4042.  https://doi.org/10.5935/0100-4042.20140040.

Materials obtained by the immobilization of 12-tungstophosphoric acid (PTA) on silica using the method of impregnation with excess solution in distinct solvents (aqueous HCl, methanol:H2O, and acetonitrile) were evaluated for use as catalysts in the methyl esterification of stearic acid. Optimum conditions were established for the impregnation of 0.5 g (w/w) of PTA on amorphous silica, under stirring at 150 rpm for 24 h, using 20 mL of 0.1 mol L-1 HCl as the solvent. After calcination at 200 ºC, high conversions were obtained under mild reaction conditions, resulting in high turnover numbers. The catalyst was evaluated in ten catalytic cycles of use, where the activity was reduced only slightly, attesting its stability and the possibility to apply it to industrial production of methylesters.

Palavras-chave : stearic acid; 12-tungstophosphoricacid; esterification.

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