CATALYTIC PROPERTIES OF SO42- TI-M-O SUPERACIDS IN ESTERIFICATION/

SO42-/Ti-M-O (M=Al, Fe, Sn) solid superacids were used in the esterifi cation of phthalic anhydride with 2-ethyl hexyl alcohol. The catalytic activity of SO42-/Ti-Al-Sn-O (1) is higher than SO42-/TiO2, and SO42- /Ti-Al-O solid superacids. In the presence of(1) DOP is prepared in go od yield at 175 degrees C over a period of 6 h. The acid strength, sur face area and catalytic activity of SO42-/Ti-M-O are obviously affecte d by the preparation conditions. Temperature-programmed desorption of pyridine adsorbed on the catalyst was used to characterize the acid st rength distribution of the catalysts. It was found that there were thr ee kinds of acid sites (weak acid, middle acid and superacid) on SO42- /Ti-Al-O, and the concentration of the middle-acid site on the catalys ts is directly proportional to its catalytic activity for the esterifi cation. Adding Al into SO42-/TiO2 could increase its surface area grea tly.