CHARACTERIZATION OF MO AL2O3 SOL-GEL CATALYST BY AL-27 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY/

The Mo/Al2O3 catalysts at various molybdenum loading was prepared by a dding (CH3COCH=C(O-)CH3)(2)MoO2 (Mo-acac), dissolved in ethanol, to th e boehmite alumina sol driven from aluminum isopropoxide (AIP). The st ructural evolution of Mo/Al2O3 gel was investigated by using Al-27 nuc lear magnetic resonance (NMR) spectroscopy and X-ray diffractometry (X RD). Al-27 NMR of Mo/Al2O3 has been compared with that of pure alumina . The addition of molybdenum species to alumina sol was to have no eff ect on the alumina structure when the molybdenum loading was lower tha n 20%. No incorporation of molybdenum species to alumina lattice was o bserved and the finely dispersed MoS2 crystallite on the support was o btained upon sulfidation. However, an Al-2(MoO4)(3) phase, which was a n indication of the interaction between Al2O3 and MoO3, was formed on the alumina surface when molybdenum loading was higher than 20%. All m olybdenum species were accessible by reactant molecules regardless of molybdenum loading.