| The synthesis of liquid fuels from coal-derived syngas via Fischer-Tropsch reaction is one of the most important processes to solve the shortage of transport fuels. The conversion of syngas on the iron-based catalysts is one of the most pivotal steps. It has been experimentally proved that the iron-based catalysts starting from their oxide precursors have complex phase transfer during the reduction as well as synthesis operation. The catalysts have different phases during different period of reaction. Consequently, the catalysts have different reaction performance.Zhong et al. had developed a novel Fe-Mn catalyst with higher activity and selectivity to synthesize light olefins and liquid fuels, which had shown transparent applications to industrialization, hi this paper, we focus on the detailed reaction performance, stability, the distribution of products and the adaptability to slurry reactor for the Fe-Mn catalyst. The reaction performance of its early period, middle and later period has been carried out in an integral fixed-bed reactor and the effects of various operation conditions including reaction temperature, pressure, inlet H2/CO ratio and space velocity are investigated. The experimental results can provide detailed information for the scale-up of Fischer-Tropsch synthesis processes based on this type of catalyst, In addition, the detailed kinetics is conducted for the Fe-Mn catalyst, which can meet the demands of catalysts improvement and reactors design.The experimental results of Fischer-Tropsch synthesis over the Fe-Mn catalyst show that high temperature is preferential for chain termination and removal of light hydrocarbon products while low temperature is preferential for chain growth and removal of heavy hydrocarbon products. The selectivity of (C2-4=) and the space time yield of hydrocarbon products are increased from 15.18 % to 25.23 %, 0.38 g/ml cat-h to 0.49 g/ml cat-h, respectively, with the change of reaction temperature from 270 ℃ to 300℃ at 2.06 MPa, syngas (H2/CO=2.00) and space velocity of 4000 h-1, whichindicated that this catalyst has high activity, good selectivity and promising productivity. The results show that the catalyst still has excellent stability and relatively high activity even during its middle (after 900 h) and later period (after 1800 h) of reaction, but methane selectivity has an apparently increase compared with that of early period. After 2200 hours, this catalyst also has relatively high activity, which indicates that this catalyst has very good longevity and promising application for the production of light olefins and high-quality liquid fuels from a coal-derived syngas with low H2/CO ratio in slurry process.The assumption that Fischer-Topscher synthesis (FTS) reactions and water gas shift (WGS) reaction take place on two kinds of active sites, carbide and Fe3O4 phases, respectively, has been deduced on the basis of the comprehensive analysis of existing catalysis knowledge. The present thesis established two kinds of detailed mechanism for FTS and one kind of mechanism for WGS reaction based on the Langmuir-Hinshelwood-Hougen-Watson or Eley-Rideal mechanisms. The detailed kinetic models of FTS, in which olefin re-adsorption is considered, are derived on the basis of the assumption of multiple slow elementary reaction steps. The parameters in the detailed kinetic models have been optimized, and the models have been discriminated by fitting the experimental data. The result shows that the detailed kinetic model of FTS based on the alkylidene mechanism can preferable fit the experimental data. The activation energy of olefins formation is 97.37 kJ.mol-1, which is smaller than that of the paraffin formation (111.48 kJ.mol-1), and this is a good explanation for the high selectivity of olefin over Fe-Mn catalyst. The deviations from the conventional ASF distribution can be quantitatively described with this kinetic model.
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