DEHYDRATION OF 4-METHYLPENTAN-2-OL OVER ZIRCONIA CATALYSTS

Several zirconia catalysts, differing in their preparative procedures and/or in the addition of dopants, have been tested for the title reac tion. The catalysts were characterized by means of calorimetric techni ques. The heats of adsorption of the probe molecules, ammonia and carb on dioxide, were measured to obtain information on the acid-base prope rties of the samples, Both flow and pulse reactors were used to invest igate the behaviour of the catalysts. 4-Methylpentan-2-ol undergoes de hydration to give 4-methylpent-1-ene, which is the desired product, an d 4-methylpent-2-ene, in variable amounts; skeletal isomers of C-6-alk enes can also form. Simultaneous dehydrogenation of the reactant to 4- methylpentan-2-one can also occur. The acid-base properties of the cat alyst appear to play a key role in governing the reaction mechanism, a well balanced number of acid and base sites being needed to obtain a good selectivity to the alk-1-ene isomer.