| Iron based catalysts modified by potassium and manganese oxides were investigated on their physicochemical discrepancies and catalytic performances in CO hydrogenation.Unmodified iron catalysts were prepared with the method of precipitation, sol-gel and impregnation. The performances of the catalysts at various reaction conditions were studied.K/Fe compound oxide catalysts were prepared by sol-gel technique. In the CO hydrogenation test under reaction conditions of 300°C,1.5 MPa syngas (H2/CO = 2, V/V),1000 h-1, 60.8 wt.% C2=～C4= were given on sample K0.04Fe. Additionally, Mn/Fe catalysts prepared by coprecipitation were in the nano scale of ca. 20 nm, and the sample of Mn/Fe (nMn/nFe = 4/96) gave high light alkenes yield of 52.1 wt.% under the conditions of 350°C, 1.5 MPa(H2/CO = 2, V/V), 1000 h-1.For the impregnated catalysts of K/Mn/Fe/Si-2, it was found that the impregnating sequence among K, Mn and Fe has great impact on the catalytic activity and selectivity in CO hydrogenation. Experimental results showed that impregnating KNO3 prior to Fe(NO3)3 on Si-2 facilitates the improvement of catalytic selectivity to light alkenes.In this paper, a modified competition model was proposed to give a logical interpretation of all the phenomena found in the experiments. In this model, the...
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