Liquid phase esterification of acrylic acid with 1-butanol catalyzed by solid acid catalysts

Esterification of acrylic acid with l-butanol has been studied in a heterog eneous solid-liquid reaction system using a variety of solid acids includin g an acidic salt of H3PW12O40, Cs2.5H0.5PW12O40 The catalytic activity (per proton) of liquid acids such as heteropolyacids, H2SO4, and para-toluenesu lfonic acid increased as the acid strength of the solution increased, but t he difference in the activity among them was not significant. In the solid- liquid reaction system, Cs2.5H0.5PW12O40 exhibited the highest catalytic ac tivity in the unit of catalyst weight among the solid oxide catalysts, whil e the activity of Cs2.5H0.5PW12O40 was less than those of organic resins su ch as Nafion and Amberlyst 15. Contrary to the liquid acids, the specific a ctivity values (per proton) of solid acids were significantly different. It was demonstrated that the activity of Cs2.5H0.5PW12O40 was almost retained after the addition of water, while the activities of the organic resins gr eatly decreased. The water-tolerant property of Cs2.5H0.5PW12O40 is presume d to be due to the hydrophobic nature of the surface. (C) 1999 Elsevier Sci ence B.V. All rights reserved.