Synthesis of Cobalt Molecular Sieve Catalyst and Influence of the Support on the Selective Oxidation of Cyclohexane

In order to investigate the influence of the pore structure and shape-selective performance of catalyst support on the selective oxidation of cyclohexane,Co incorporating molecular sieve Co/S-1,Co/TS-1 and Co/MCM-41 were hydrothermally synthesized by one-pot synthesis method.The prepared samples were characterized by XRD,TEM and IR.The results showed that Co had incorporated into the matrix of all samples with good crystallinity and regular particle morphologies.The catalytic performance of the samples for the cyclohexane liquid-phase oxidation into cyclohexanone and cyclohexanol by oxygen was investigated in the absence of solvents.The catalytic activities were also compared with CoAPO-5,Co/Al_(2)O_(3) as well as Co(OAc)_(2)·4H_(2)O which used as homogeneous catalyst.Experiment results suggested that the use of molecular sieve support improved the cyclohexane conversion as well as the selectivity of cyclohexanol and cyclohexanone,accordingly reduced the dependence of the cyclohexanone and cyclohexanol selectivity on the cyclohexane conversion.The selectivity to cyclohexanone and cyclohexanol was inclined with the increase of the pore diameter of the molecular sieve support.Co/S-1 and Co/TS-1 with the smaller pores showed superior selectivity to Co/MCM-41,CoAPO-5,Co/Al_(2)O_(3) as well as Co(OAc)_(2)·4H_(2)O.96.7% selectivity to cyclohexanol and cyclohexanone at 5.2% conversion of cyclohexane was obtained over Co/S-1 at 140 ℃ for 3 h.