The reduction behavior of iron-based catalysts modified by different additives was investigated by H2-TPR. As shown in Fig. , all the catalysts exhibit two reduction peaks, corresponding to the reduction of Fe3O4 to FeO and the reduction of FeO to elemental Fe , respectively. The reduction temperature for Fe120K10 and Fe120Zn20K10 are around 390 and 580 ℃. After the incorporation of Cu and Mn promoters, the temperature for the first reduction peak shifted to 300 ℃ probably owing to the good H2 dissociation ability of copper and the strong interaction between Fe and Mn species promoting the reduction of Fe3O4 to FeO . In addition, the Mn additive-modified iron-based catalyst also showed an H2 reduction peak corresponding to MnO2 in the 400-600 °C interval .