Synthesis, characterization and catalytic activity of oleic acid-coated TiO2 nanoparticles carrying MoO2 (acac)2 in the oxidation of olefins and sulfides using economical peroxides
Abstract
Titanium oxide nanoparticles were synthesized by a modified polymerized complex derived sol–gel method followed by coating with oleic acid (OA) to modify their surface. The reaction with MoO2 (acac)2 yielded the TiO2–OA–MoO2 nanocomposite as a supported cis-dioxomolybdenum complex. The structural and morphological characterization of the as-prepared TiO2 and TiO2–OA–MoO2 were carried out by different techniques such as XRD, FT-IR, TGA and TEM. The catalytic activity of the TiO2–OA–MoO2 nanocomplex in the epoxidation of olefins and oxidation of sulfides to sulfoxides using H2O2 in ethanol as a safe solvent was investigated. The reactions also proceeded efficiently in the presence of tert-butylhydroperoxide (TBHP). Good/high yields and excellent selectivity were obtained. The recovery of the title heterogeneous nanocatalyst was easy and efficient and its catalytic activity was strikingly different from other nanooxometals such as m-ZrO2, MoO3, Fe3O4 and TiO2, as well as their nanocomposites such as TiO2–OA, ZrO2–OA–MoO2, MoO3–OA–MoO2 and Fe3O4–OA–MoO2.