A series of Fe/MgO catalysts were prepared by impregnation method and characterized by XRD and CO2-TPD.Selective synthesis of acrylonitrile from acetonitrile and methanol was carried out in a conventional flow reactor system.The effects of Fe loading and reaction temperatures on the catalytic properties of Fe/MgO were studied.Experimental results show the catalytic properties was greatly improved by the addition of Fe to MgO.As Fe loading was 5%,it had the best catalytic property with conversion 22.6% of acetonitrile and with selectivity to acrylonitrile 81.9% at 400℃.Excess addition of Fe results in a decrease in activity and selectivity.CO2-TPD showed that stronger and less base sites on the surface of catalysts were both unfavorable for the reaction.
A series of CexPr1-xO2-δ mixed oxides were synthesized by sol-gel met hod and characterized by Raman and XRD techniques. When x value was changed from 1.0 to 0.5, only a cubic phase CeO2 was observed. The samples were very well cr ystallized on decreasing x from 0.50 to 0.99. For CexPr1-xO2-δ samples 465 cm-1 and 1 150 cm-1 Raman peaks are attributed to the Raman active F2g mode of CeO2. The broad peak at about 570 cm-1 in the region of 0.3 ≤ x ≤ 0.99 can be linke d to lattice defects resulting in oxygen vacancies. The new band at about 195 cm -1 may be attributed to the asymmetric vibration caused by the formation of oxyg en vacancies. Calcination temperatures had great effect on the peak intensity fo r CeO2 but less effect on Ce0.8Pr0.2O2-δ in Raman spectra. It might be due to t he transformation of the colors for the mixed oxides, the insertion of Pr atom i nto the ceria lattice could enhance the sintering resistance and thermal stabili ty of the mixed oxides.
