COLL 173 |
| John W. Geus, I. J. Dijs, and Leonardus W. Jenneskens. Debye Institute, Dept. of Physical Organic Chemistry, Utrecht University, Utrecht, Netherlands |
| The fairly inconsistent literature about sulfated zirconia catalysts suggests that reaction of zirconia with sulfuric acid, subsequent removal of part of the sulfate by thermal treatment and extent of hydration determine the activity. We prepared bulk zirconium sulfate by reaction of zirconium chloride with sulfuric acid, supported zirconium sulfate by applying zirconia on a silica support and reacting the zirconia with sulfur trioxide, and usual sulfated zirconia. The activities were assessed in the gas-phase transalkylation of diethylbenzene with benzene and the liquid-phase reaction of camphene with acetic acid. The activity appears to be governed by the equilibrium Zr(SO4)2 + 4H2O <-> Zr(SO4)2.4H2O + nH2O <-> ZrO2 + 2H2SO4.(n+2)H2O Neither water-free zirconium sulfate nor the tetrahydrate is catalytically active. To prevent formation of a diluted adsorbed sulfuric acid phase, formation of the tetrahydrate has to be prevented. Consequently reaction with sulfuric acid is preferably confined to the surface layer. |
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The Science and Engineering of Catalyst Preparation
2:00 PM-5:25 PM, Monday, March 29, 2004 Marriott -- Orange County 3, Oral
Division of Colloid and Surface Chemistry |