Study of cobalt molybdenum oxide supported on mesoporous silica for liquid phase cyclohexane oxidation

Liquid phase oxidation of cyclohexane, by molecular oxygen, has been carried out using cobalt molybdenum oxide (CoMoO4) catalyst supported on mesoporous silica supports (SBA-15, KIT-6 and FDU-12). For each support, the catalyst activity has been studied as a function of loading, pore size, and calcination temperature. The catalysts were characterized using surface area analysis (BET), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Among the three supported catalysts, the one on FDU-12 shows the highest activity. The catalysts with lower loading, lower calcination temperature and lower pore size of support show higher activity but with lower selectivity. All the studied catalysts gave about 7-8% conversion, with selectivity of 85% for cyclohexanone and cyclohexanol (KA oil), before deactivation took over. The deactivated catalysts could be fully regenerated by re-calcination in every case. With such regeneration between runs, the catalysts are shown to retain their activity and selectivity over multiple cycles. The kinetic model which was proposed for the unsupported catalyst has been shown to work well for the supported catalysts as well.