Catalytically active centres in porous oxides: design and performance of highly selective new catalysts

Active centres have been designed on high-area, molecular sieve catalysts which, inter alia, can convert n-alkanes to n-alkanols and n-alkanoic acids, cyclohexane to cyclohexanol, cyclohexanone and adipic acid, and n-hexane to adipic acid all using either oxygen or air as oxidants. A number of one-step processes and solvent-free chemical conversions, of paramount importance in the development of clean technology, are also described with catalysts designed (i) to oxidise p-xylene to terephthalic acid aerobically, (ii) to effect Baeyer–Villiger reactions with oxygen, and (iii) for the conversion of cyclohexanone to ε-caprolactam under mild conditions. The inner surfaces of mesoporous silicas may also be atomically engineered so as to yield high-performance epoxidation of alkenes at TiIV-centred active sites, as well as enantioselective hydrogenations of organic species using constrained chiral catalysts.