THE ACIDITY OF ZIRCONIUM-PHOSPHATES IN RELATION TO THEIR ACTIVITY IN THE DEHYDRATION OF CYCLOHEXANOL
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Three samples of zirconium phosphate varying in crystallinity from amorphous to highly crystalline were prepared and characterized as to surface area, surface acidity, and activity in cyclohexanol dehydration. The number of strong acid groups was found to increase with increased temperature of pretreatment of the solids, except for the amorphous exchanger. For that solid condensation of hydroxyl groups is significant at temperatures of 200400 C reducing the surface acidity. The dehydration reaction was found to be first order in alcohol concentration and to increase in rate with increase in the number of strong acid groups. The reaction was poisoned by the exchange of surface protons with Cs+ or introduction of quinoline into the feed stream. Thus, the active sites must be the monohydrogen phosphate protons. However, a small amount of activity is due to a second site probably of the Lewis acid type. 1980, All rights reserved.