Environmental Friendly Titanium Pillared LDHs Supramolecule Catalyst

Facing the increasing seriously environmental problems, the world has seen a more and more stringent level for sulfur content in liquid fuels proposed in many countries. Currently, oxidative desulphurization (ODS) become the hotspot which is investigated extensively for its mild reaction condition, simple equipment, and high efficiency. Titanium containing materials as efficient oxidative catalyst has attracted the interest of many research groups.In this study, a water-soluble titanium compound peroxotitanium has been intercalated within the gallery spaces of the layered double hydroxides (LDHs) using anion exchange technique, and a titanium pillared LDHs supramolecule was obtained.By tuning the pH value and concentrations of the peroxotitanium solutions, the ratio of the Ti/Al and the initial of the host layer, peroxotitanium pillared LDHs with different crystallite size and host metal composition have been synthesized. Elemental analysis, X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, XPS spectroscopy, SEM and HR-TEM have been used to characterize these materials. TEM micrographs of LDH-Ti materials revealed platelike morphology, characteristic of hydrotalcite-like compounds. The expansion was 0.54 nm corresponding to the dimension of the peroxotitanium. The structural model of the peroxotitanium pillared LDHs was proposed. The thermal stability of the intercalates was studied through TG/DTA/MS and in situ HT XRDThe quantitative oxidation of organic sulfides to sulfoxides and sulfones with 30% aqueous hydrogen peroxide as the oxidant were applied as the probe reactions, the effect of the crystallite size, the size of the substrate and host metal composition of the intercalates were all studied. The selectivity of sulfoxide differs with the divalent metal of the host layer, and the TON value was influenced by the different crystallite size. The substrate with different size exhibited different diffusion behavior over the catalyst. The selected Mg₂Al-Ti LDHs-40 possessed two major advantages over titanium peroxotitanium sol-gel, namely, stability toward hydrolysis and greater recyclability.