Epoxidation of olefins catalyzed by a molybdenum-Schiff base complex anchored in the pores of SBA-15

• The SBA-15 modified with amine or salicylaldehyde by 2 one pot synthetic approaches.
• Novel mesostructured hybrid materials containing molybdenum Schiff base complex.
• High-efficiency catalysts for the selective oxidation of olefins.
• The catalysts exhibited remarkable recyclability for six consecutive cycles.

Novel mesostructured hybrid materials containing a molybdenum Schiff base complex grafted on the internal surface of SBA-15 pores were prepared by introducing MoO2(acac)2 into a mesoporous silica functionalized with Schiff base ligands. The SBA-15 supports modified by an amine or salicylaldehyde were obtained by co-condensation of tetraethylorthosilicate and the corresponding organosilane in the presence of Pluronic P123 surfactant as a structure directing agent using bis[3-(trimethoxysilyl)propyl]amine or 5-chloromethylsalicylaldehyde coupled with bis[3-(trimethoxysilyl)propyl]amine as precursor. The molybdenum (VI) complexes immobilized on the internal surface of SBA-15 pores were employed as catalyst in the epoxidation of various alkenes using tert-butylhydroperoxide as oxidant. These immobilized molybdenum complexes are highly active and selective catalysts in liquid phase olefin epoxidation in dichloroethane at 84 °C. Leaching tests and metal analysis of reaction solutions showed that the kinetically competent catalyst is the molybdenum complex immobilized on the internal surface of SBA-15 pores and there is no molybdenum species in the solution.

Figure optionsDownload high-quality image (200 K)Download as PowerPoint slide