화학공학소재연구정보센터
Catalysis Today, Vol.41, No.4, 387-407, 1998
Liquid phase oxidation at metal ions and complexes in constrained environments
Various approaches towards the rational design of novel catalysts based on the concept of confinement (site-isolation) of redox active metal centres in molecular sieves are reviewed. These comprise (a) substitution of T elements (Si, Al and P) in the framework of silicates, zeolites, AIPOs and SAPOs, (b) encapsulation of metal complexes in intrazeolite space (ship-in-a-bottle catalysts) and (c) grafting or tethering of metal complexes to the internal surface of the molecular sieves. Related materials - redox pillared clays, clay intercalated metal complexes, redox aerogels and metal complexes incorporated in aerogels - are also reviewed. The advantages and limitations of the various materials with regard to activity and selectivity as catalysts for liquid phase oxidations with O-2, H2O2 and RO2H and stability towards leaching, are discussed.