The hydration of ethylene was carried out over different metal phosphates a
nd phosphoric acid impregnated metal phosphates at high pressure. The catal
ysts were compared to phosphoric acid on silica, which is used in the indus
trial application of the reaction. The impregnated phosphates showed slight
ly higher conversions than phosphoric acid on silica. It was shown by X-ray
diffraction that aluminum and zirconium phosphate are, like silica gel, no
t inert against phosphoric acid. The activity of the catalysts, the amounts
of leached phosphoric acid, the determination of the surface areas, of the
free phosphoric acid, and of the acidity indicated that the catalytically
active compound is liquid phosphoric acid. (C) 2001 Elsevier Science B.V. A
ll rights reserved.