Study On Slurry Phase Fused Iron Catalysts For Fischer-Tropsch Synthesis

The Fischer-Tropsch synthesis （FTS） offers the potential of converting syngas into high value chemicals and liquid fuels. Reaction temperature is generally higher between 300℃-400℃with traditional fused-iron catalysts for Fischer-Tropsch synthesis, so it is also called high-temperature Fischer-Tropsch synthesis catalyst and is usually used in fixed bed or fluidized bed reactor. The slurry reactor is effective in the removal of reaction heat which can avoid temperature rise in catalysts bed and CH4 selectivity increased because of the use of liquid paraffin for the media. At the same time, slurry reactor with reasonable products distribution, convenience for loading and unloading catalysts has therefore become the focus of the current development of industrial technology. Due to restrictions of the boiling point of medium paraffin wax （about 300℃）, reaction temperature is generally lower than 280℃in slurry reactor, so it is not suitable for traditional fused-iron catalysts used in slurry reactor, and it is not relationally reported. Reaction temperature must be reduced in order to use in slurry reactor.According to preliminary studies, the promoters and reaction conditions were studied in this paper in slurry reactor and characterized by means of XRD, TPR, BET and SEM and so on in oreder to get better insight into the relationship therein. The structure and fluid mechanics in continuous stirred tank were also studied. Main results from this work were as follows.Gas holdup increases with superficial gas velocity, and gas holdup reduces with the increase of solid holdup. When the solid holdup increases from 4% to 10%, CO, H₂ and CO+H₂ conversion increase, but the selectivity of CO₂ gradually lowers.Selectivity of CH₄ and reaction of CO water-gas shift are inhibited as A content gradually increases.Conversion of H₂ and CO+H₂ reduces and selectivity of CH₄ and CO₂ increases as C content increases. Promoter E only improves the alkene and alkyl ratio of C₂-C₄. The selectivity of CO₂ and CH₄ reduces as E content gradually increases.The study of reaction conditions indicated that the high pressure, the lower temperature, H₂/CO ratio and lower space velocity, the formation of methane was greatly suppressed. Fused-iron catalyst has a very good activity and stability in the slurry reactor. It is feasible to use low-temperature fused-iron catalyst in slurry phase for Fischer-Tropsch synthesis...