03/01706 Partial oxidation of methane to synthesis gas using lattice oxygen instead of molecular oxygen: Li, R. et al. Cuihua Xuehao, 2002, 23, (4), 381–387. (In Chinese)

Abstract

The redox performance of Fe 2O 3, which was used as a provider of lattice oxygen, was investigated by using thermogravimetry under a methane flow. The lattice oxygen in Fe 2O 3 can react with CH 4 to form CO 2 and H 2O while Fe 2O 3 is reduced through steps Fe 2O 3→Fe 3O 4 and Fe 3O 4→FeO→Fe. The redox circulation technique combined with on-line quadrupole mass spectrometric analysis was used to study the feasibility of the methane oxidation to synthesis gas using lattice oxygen instead of molecular oxygen. The switching reaction between 13%O 2/He and 6.5%CH 4/Ar at a flow rate of 31 ml/s and 750 ℃ was carried out in a fixed-bed reactor, in which 100 mg Fe 2O 3 was placed on the layer of Ni/Al 2O 3 catalyst (400 mg). The results show that methane can be converted to CO and H 2. During the CH 4 reaction step, about 25% methane is oxidized to CO 2 and H 2O by lattice oxygen from Fe 2O 3 and the remaining 75% methane is reformed with CO 2 and H 2O over the Ni/Al 2O 3 catalyst to produce synthesis gas. During the O 2 reaction step, lower valence iron oxide is reoxidized by molecular oxygen to its initial state. Using a suitable period of redox circulation, high conversion of methane and high selectivity to synthesis gas could be obtained over Fe 2O 3 and Ni/Al 2O 3 catalyst. These results indicate that methane can be oxidized to synthesis gas by using lattice oxygen instead of molecular oxygen through a combustion-reforming mechanism.