Sol-gel method preparation and characterization of NiMoO4 ultrafine particle catalyst

Ni-Mo ultrafine particle samples have been prepared by sol-gel method with citric acid as complexant. DTA, BET, XRD and LRS have been employed to characterize the structures of the samples obtained by calcining the Ni-Mo gel at various temperatures. The results show that when the Ni-Mo gel is calcined in air at 210 degrees C, citric acid reacts violently with O-2, it produces a flash heat and results in an aggregation of the Ni-Mo particles. When the gel is calcined in argon, citric acid is removed mildly and NiMoO4 ultrafine particles are formed. After calcined at 500 degrees C, the ultrafine particles grow up with a decrease of BET surface area from 51.5 m(2) . g(-1) to 25.0 m(2) . g(-1).