不同放大级Fe／Cu／K／SiO2催化剂的表征及其浆态床费托合成反应性能

Characterization and Slurry Fischer-Tropsch Synthesis Performance of Fe/Cu/K/SiO_2 Catalysts with Different Scaled-Up Levels

采用连续共沉淀和喷雾干燥成型相结合的方法,制备了实验室级和放大级微球状费托(FT)合成Fe/Cu/K/SiO2催化剂.实验室级催化剂的颗粒尺寸为5～15μm,放大级催化剂的颗粒尺寸为40～60μm.利用低温N2物理吸附、H2程序升温还原、CO2程序升温脱附、穆斯堡尔谱和X射线衍射等表征手段考察了催化剂的织构性质、还原行为、碳化行为及物相变化.结果表明,与实验室级催化剂相比,放大级催化剂具有较大的晶粒尺寸和孔径、较小的比表面积和较弱的表面碱性,催化剂的还原和碳化受到抑制.浆态床FT合成反应及扫描电子显微镜结果表明,放大级催化剂经诱导期达到稳定状态后,转化率可达到实验室级催化剂的水平,且具有很高的稳定性、重质烃选择性及抗磨损性.

Two spherical Fe/Cu/K/SiO2 catalysts with different preparation scale for slurry Fischer-Tropsch （FT） synthesis were prepared by a combination of co-precipitated and spray drying method. The pellet size of the catalyst with a laboratory scale is 5-15 μm, whereas that is 40-60 μm for the scaled-up catalyst. N2 physical adsorption, H2 temperature-programmed reduction, CO2 temperature-programmed desorption, M6ssbauer spectroscopy, and X-ray diffraction were used to characterize the textural properties, reduction and carburization behavior, and phase transformation of the two catalysts. The results show that the scaled-up catalyst has larger crystallize size and pore volume, lower BET surface area, and lower surface basicity than the laboratory-scale catalyst. Moreover, the scaled-up catalyst was more difficult to be reduced and carburized. However, the results of FT synthesis in a slurry bed indicate that the scaled-up catalyst exhibits comparative activity, better reaction stability, and higher selectivity for olefin and heavy hydrocarbons. Scanning electron microscopy results suggest a better attrition resistance of the scaled-up catalyst during the FT reaction tests.