Preparation, characterization, and catalytic properties of ultrafine mixedFe-Mo oxide particles

Ultrafine mixed Fe-Mo oxide particles are prepared by the sol-gel technique using citric acid as a complex agent. The formation process of the ultrafi ne oxides is studied by using XRD, DTA-TG, FT-IR, TEM, and BET surface area measurement, It is found that the morphology and structure of the oxide pa rticles are significantly dependent on the process parameters such as therm al treatment temperature (T), pH of the starting solution, and the molar ra tio of citric acid to metallic ions (L/M), The formation temperature of cry stalline Fe-2(MoO4)(3) by the sol-gel process is much lower than that by th e coprecipitation method. The catalytic properties of ultrafine Fe-Mo oxide particles are tested and compared with those of large oxide particles havi ng the same composition. It is shown that for selective oxidation of toluen e to benzaldehyde the ultrafine Fe-Mo oxide particles exhibit higher benzal dehyde selectivity and toluene conversion than the large oxide particles, T he unique catalytic properties of ultrafine Fe-Mo oxide particles may be co rrelated to the higher mobility of lattice oxygen species in the ultrafine oxide particles and their higher BET surface area. (C) 1999 Academic Press.