Selective Oxidation of Cyclohexane over Transition-Metal-Incorporated HMS in a Solvent-Free System

Mesostructure materials A-HMS (A = Ce, Ti, Co, Al, Cr, V, Zr) were synthesized with cetylamme as the structure director and tetraethyl orthosilicalue as the silica source CeO2/V-HMS and CeO2/Al-HMS were prepared by dipping-calcination method The materials were characterized by X-ray diffraction (XRD), UV-vis, Fourier transform infrared (FT-IR). N-2 adsorption-desorption, inductively coupled plasma atomic emission spectroscopy (ICP-AES), transmission electron microscopy (TEM), and Al-27 magic wide spinning nuclear magnetic resonance (MAS NMR). The incorporated ions were mostly in the framework of the mesoporous materials, which were confirmed by the XRD. FT-IR, UV-vis, and Al-27 MAS NMR analyses The solids obtained were employed as heterogeneous catalysts for the selective oxidation of cyclohexane with oxygen (O-2) as oxidant in a solvent-flee system. The material CeO2/V-HMS exhibited the highest activity with about 18% conversion of cyclohexane but 68% total selectivity to cyclohexanol and cyclohexanone The performance of Al(40)-HMS is satisfying for nearly 10% conversion of cyclohexane and 93% total selectivity to the desired products Also, Al(40)-HMS is efficient rot its excellent recyclable property in the oxidation of cyclohexane.