Abstract:
A series of spinel catalysts, including ZnFe
2O
4, MgFe
2O
4, CuFe
2O
4, and MnFe
2O
4, were prepared and applied to the Fischer-Tropsch synthesis (FTS). Zn, Mg, Cu and Mn easily form spinels with Fe. Among them, Zn and Mg can significantly maintain the spinel structure during the pretreatment and reaction, resulting in a low CO conversion. Cu and Mn are beneficial to the formation of iron carbide during the reaction, resulting in an apparent influence on FTS performance. ZnFe
2O
4 has little effect on the hydrocarbon distribution and the olefin/paraffin (O/P) ratio of C
2−C
4. MgFe
2O
4 exhibits low selectivity for C
5+ hydrocarbons, and the selectivity of \mathrmC_2^=-\mathrmC_4^=\; and the O/P ratio of C
2−C
4 in the product are increased due to the alkaline effect of Mg. Cu can promote the carbonization of the catalyst, so that CuFe
2O
4 has higher activity. Meanwhile, CuFe
2O
4 can significantly improve the selectivity of C
5+ hydrocarbons. Moreover, Cu can promote the dissociation and activation of H
2, which is beneficial to the secondary hydrogenation of olefins, thereby reducing the selectivity of \mathrmC_2^=-\mathrmC_4^=\; and the O/P ratio of C
2−C
4. Mn promotes carbonization during the reaction, but MnFe
2O
4 has little effect on the chain growth of hydrocarbon. However, Mn can promote the generation of a certain amount of
ε-Fe
2C, which may explain the higher selectivity of \mathrmC_2^=-\mathrmC_4^=\; and the O/P ratio of C
2−C
4 for MnFe
2O
4. All spinel catalysts exhibit low CO
2 selectivity, which meets the current green environmental protection requirements.