Abstract: Cr₂O₃ catalysts were prepared by citric acid method and direct decomposition of Cr(NO₃)₃. The POM reactions were carried out in a flow-type fixed bed micro reactor(quartz tube, i.d. 5 mm) at atmospheric pressure. The influences of reaction temperature and space velocity on POM reaction were investigated. The results show that the conversion of methane, selectivities of CO and H₂ increase with the reaction temperature(500-750 ℃) and the oxygen is almost exhausted under the conditions of GHSV=12×10⁴ h^-1 and V(CH₄)∶V(O₂)=2. Furthermore, the conversion of methane, selectivities of CO and H₂ increase with the GHSV(6.0×10⁴-24×10⁴ h^-1) under the conditions of V(CH₄)∶V(O₂)=2 at 700 ℃. In 500 h on stream, the conversion of methane, selectivities of CO and H₂ decrease slowly with the time on stream and the oxygen is almost exhausted under the conditions of GHSV=12×10⁴ h^-1 and V(CH₄)∶V(O₂)=2 at 700 ℃. The results of X-ray diffraction(XRD), TEM and BET specific surface area showed that the sinter of Cr₂O₃ catalyst may be responsible for the deactivation of Cr₂O₃ catalyst. Methane pulse reaction was carried out and the results indicated that the POM mechanism over Cr₂O₃ catalyst may be Mars-Van Krevelen mechanism.

Key words: Cr₂O₃, Partial oxidation of methane, Syngas, Lattice oxygen, Pulse reaction