Preparation and properties of Ti-containing MCM-41

The new policies on environment preservation are directing the chemical processes to not only avoid the use of unfriendly reactants and catalysts but also to find more selective catalysts that minimize product waste and/or expensive separations and recycling. Zeolites doped with V and Zn can selectively oxidize n-butane to maleic anhydride. Pd/Cu–Y zeolites can replace the homogeneous Pd and Cu salts for the oxidation of short-chain olefins to carbonyl compounds using molecular oxygen. Metal phthalocyanine complexes entrapped in zeolites have also shown great activity and selectivity for the oxidation of alkanes, cycloalkanes, olefins, and alcohols using iodosobenzene and air as oxidants. An important advance in oxidation catalyst was given when Ti and V containing zeolites were shown to be active and selective to carry out the oxidation of different hydrocarbons with H2O2. Thus, the isomorphous substitution of Si by Ti and/or V into the framework of MFI and MEL zeolite structures leads to materials that show good activity and selectivity for the oxidation of phenol to catechol and hydroquinone, olefins to epoxides, and alkanes to alcohol and ketones using H2O2 at relatively low temperatures. However, in the field of fine chemicals, it is sometimes required to oxidize large molecules that cannot penetrate in the narrow pores of the MFI structure.