Selective epoxidation of olefins over Co(II)-Schiff base immobilised on KIT-6

Co-Salen complex immobilised on amine functionalised mesoporous KIT-6 (Co-S-KIT-6) was prepared by post synthetic method. The synthesised materials were characterized by techniques such as small angle XRD, FT-IR, DRSUV-vis, thermal analysis, N-2 sorption, ESR, SEM and TEM. The small angle XRD patterns, N2 sorption studies and TEM images clearly revealed immoblisation of Co-Salen complex inside the pores of KIT-6. Further, decrease in the surface area, pore volume and pore diameter compared to parent KIT-6 also confirmed the immobilisation of Co-Salen complex inside the mesopores. The catalytic activity of Co-S-KIT-6 was tested in the liquid phase epoxidation of olefins using H2O2 as the oxidant. The influence of reaction parameters such as catalyst amount, reaction temperature, solvent and reaction time on the catalytic activity of Co-S-KIT-6 was also studied. The solvent polarity played a key role in the conversion and selectivity. Polar aprotic solvent such as acetonitrile exhibited high conversion with high selectivity of the product. Further, it was demonstrated that Co-S-KIT-6 can be recycled upto five cycles without loss of its catalytic activity. In addition, the catalyst was found to be highly active, stable and selective. (C) 2013 Elsevier B.V. All rights reserved.