Loading Of Moo <sub> 3 </ Sub> Catalyst And Catalytic Esterification

The preparation and characterization of supported MoO3/SiO2 and MoO3/γ-Al2O3 catalyst were studied. A series of MoO3/SiO2 and MoO3/γ-Al2O3 catalysts with varying MoO3 loading(5-30wt%) were prepared by impregnation using the high surface area of silica,γ-Al2O3 and ammonium heptamolybdate (AHM). The samples were characterized by X-ray diffraction(XRD), Specific surface area measurements (BET),and Temperature-programmed desorption of NH3(NH3-TPD). The catalytic esterification of acetic acid with ethanol was carried.MoO3/SiO2 catalysts were prepared by the impregnation method. The surface composition of catalyst was characterzed by XRD, BET and NH3-TPD techniques. The results indicated that the optimal preparation conditions of MoO3/SiO2 are:20wt% Mo loading, calcination temperature 450℃, baking time 4h, in the above conditions, the conversion rate of acetic acid is 79.4%, and the selectivity to ethyl acetate is 100%; the experimental results show that the optimal reaction conditions are:reaction temperature 98℃, n(acid):n(alcohol)=1.4:1, reaction time 3h, w(catalyst)=1.9%(compared to the quality of the raw materials). XRD investigation showed that, the MoO3 loading of 20wt% close when capacity is calculated in the theory MoO3 single scattered on the carrier SiO2, MoO3 amorphous be highly dispersed on the carrier; Specific surface area measurements (BET) investigation showed that, MoO3/SiO2 catalyst is porous structure that includes both micro-pore and medium pore structure; Temperature-programmed desorption of NH3(NH3-TPD) indicated the uniquely existed weak Lewis acid sites in the MoO3/SiO2.MoO3/γ-Al2O3 catalysts were prepared by the impregnation method. The surface composition of catalyst was characterzed by XRD, BET and NH3-TPD techniques. The results indicated that the optimal preparation conditions of MoO3/γ-Al2O3 are:25wt% Mo loading, calcination temperature 500℃, baking time 4h, in the above conditions, the conversion rate of acetic acid is 79.5%, and the selectivity to ethyl acetate is 100%; the experimental results show that the optimum reaction conditions are:reaction temperature 98℃, n(acid):n(alcohol)=1.4:1, reaction time 3h, w(catalyst)=2.4%(compared to the quality of the raw materials). XRD investigation showed that MoO3 amorphous state with highly dispersed on the carrier when MoO3 loading is 25wt%; Specific surface area measurements (BET) investigation showed that MoO3/γ-Al2O3 catalyst is single porous structure, and medium pore structure. Temperature-programmed desorption of NH3(NH3-TPD) indicated the uniquely existed weak Lewis acid sites in the MoO3/γ-AlO3.