Organic–inorganic hybrid catalysts containing new Schiff base for environment friendly cyclohexane oxidation

Abstract

Organic and inorganic entities have been hybridized using 3-aminopropyltriethoxysilane (APTES) linker for the synthesis of three novel organic–inorganic hybrid catalysts [Cu(II), Co(II) and Ni(II)]. During the course of the synthesis, the static inorganic moiety was functionalized with versatile imine (CN) groups. The prepared catalysts were characterized by spectral techniques (EDS, FT-IR, DR UV-Vis., ²⁹Si CP/MAS NMR, powder-XRD and ESR), thermal study (TG-DTG) and surface studies (SEM and AFM). The reported catalysts are significant because of their geometrical and dispersive surface properties. The synthesised catalysts were tested with cyclohexane oxidation reactions using H₂O₂, to make the catalytic system eco-friendly. Compared to the previously reported catalysts, the present catalysts have shown better cyclohexane conversion and selectivity, and are also cost effective. Among the three catalysts studied, Cu(II) catalyst showed the maximum conversion efficiency (44%) with product selectivity of 29% cyclohexanol and 71% cyclohexanone. Because of the combination of interesting structural properties and acceptable catalytic property with better selectivity and environment benign character along with a low cost, these hybrid catalysts could be the best future catalysts for cyclohexane oxidation.