还原空速对Fe/Cu/K/SiO_2催化剂浆态床F-T合成性能的影响

Effect of space velocity in syngas reduction on performance of Fe/Cu/K/SiO_2 catalyst for slurry phase Fischer-Tropsch synthesis

在浆态床反应器中详细考察了合成气还原空速对微球状工业铁基催化剂还原和反应后的物相以及F—T合成反应性能的影响．研究结果表明：空速能够影响铁基催化剂还原反应进程，催化剂在较高的空速下易被还原，还原后催化剂的比表面积降低，平均孔径增大．在较低空速下还原时，还原形成的高的CO2分压对铁物相有一定的氧化作用，使得还原态催化剂中的Fe抖（spin）含量增大．还原空速对FT合成烃产物分布影响不明显，但对催化剂的反应活性和运行稳定性影响较大，较低和较高空速还原后的催化剂失活速率均较高，适宜的还原空速为1．0～2．0L·（g cat）^-1·h^-1．

The effects of space velocity in syngas reduction on the reaction performance of the FischerTropsch synthesis （FTS） over a spray-dried spherical Fe/Cu/K/SiO2 catalyst and on the bulk compositions of the reduced and used catalysts were investigated in a continuous stirred slurry reactor under reaction conditions of 250--280 ℃, 1.5 MPa, H2/CO=0.67 and 2.0 L · （g cat）^-1· h^-1. The results showed that the BET surface area of the reduced catalysts decreased with the increase of the space velocity in reduction, and the reverse trend for the average pore diameter was observed. The space velocity in syngas reduction did affect the reduction process. The catalyst was easier to be reduced at a higher space velocity. The higher partial pressure of CO2 in slurry reactor during reduction could partially oxidize the iron carbide. And the content of Fe^3＋ （spm） was higher in the reduced catalyst. The space velocity in syngas reduction had no obvious effect on the hydrocarbon selectivity, and the effect of the space velocity in syngas reduction on the catalyst activity and stability was significant. The deactivation rate of the catalyst was higher at both lower and higher space velocity. The appropriate space velocity in syngas reduction was 1.0--2.0 L· （g cat）^-1 · h^-1.