The active sites of perrhenate supported on ?-alumina, a heterogeneous olefin metathesis catalyst, are generated when the catalyst is exposed to an olefin substrate. The kinetics of activation were observed by conducting propylene homometathesis in a batch reactor. The temperature-dependence of the apparent rate constants for both the activation and metathesis reactions were measured. The former shows typical Arrhenius behavior, with Ea = (61 � 12) kJ/mol. However, the kinetics of olefin metathesis showed an unexpected, inverse dependence on temperature.  Decreased catalytic activity at higher temperatures is attributed to a smaller number of active sites, which is a result of more rapid deactivation. Metathesis activity is dramatically enhanced by ZnCl2-modification of the alumina. The effect is attributed to alumina chlorination.

Understanding and improving supported perrhenate catalysts for olefin metathesis

244th National Meeting (2012)

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