REDOX MOLECULAR-SIEVES AS HETEROGENEOUS CATALYSTS FOR LIQUID-PHASE OXIDATIONS

Redox molecular sieves have been synthesized by isomorphous substitution of chromium in the framework of silicalite-1 and AlPO-5. CrS-1 was shown to be an effective catalyst for the oxidative cleavage of styrene to benzaldehyde at 70 degrees C. CrAPO-5 catalyzes the selective oxidation of secondary alcohols to the corresponding ketones, alkylbenzenes to acetophenones and cyclohexane to cyclohexanone, using TBHP or O-2 as the terminal oxidant. Both CrS-1 and CrAPO-5 could be recycled without loss of activity and no leaching of chromium from the catalyst occurred. In the case of CrAPO-5 evidence is provided for the reaction taking place inside the cavity of the molecular sieve.