On the Nature of Ti(IV)-Pillared Layered Metal Hydroxides Prepared from Green, Water-Soluble Ti-Peroxide

摘要

Ti-peroxide pillared layered double hydroxides (LDHs) have been prepared for the first time using water-soluble Ti-peroxide as an intercalating precursor. It is novel and alluring that the whole preparation procedure does not involve any usage of organic or chlorine-containing hazards. Intercalated into the LDH interlayer region, Ti-peroxide is prevented partially from condensation in the solvent evaporation. The interlayer Ti—O2 unit exists in triangular (η~2) structure with C_(2v) symmetry in most cases, giving an interlayer gallery of 0.50-0.60 nm. But in the case of pH 4.0, monodentate (η~1) structure is also observed, giving an interlayer gallery of 0.70 nm. All the Ti-peroxide pillared LDHs prepared in this work show catalytic activity in the selective oxidation of thioether. The Ti-peroxide introduced into the interlayer regions of Mg/Al LDH with a particle size of around 50-120 nm exhibits better recyclability than Ti-peroxide gel, either in bulk or adsorbed on the exterior surface of LDH particles.