To study the flow process of the Fischer?Tropsch (FT) catalyst in the gas?solid fluidized bed, the main physical parameters of the catalyst were analyzed firstly. And then the flow behaviors of the FT catalyst in different superficial gas velocities in the fluidized bed with different diameters were measured. Finally the flow behaviors of the fluid catalytic cracking (FCC) catalyst, which was widely used in the field of catalytic cracking of petrochemical industry, were compared with that of the FT catalyst. It was found that, although the FT catalyst and the FCC catalyst were both Geldart-A particles, the FT catalyst had smaller stagnation angle (almost 75% of that of the FCC catalyst). This caused that the FT catalyst had lower minimum fluidization velocity, less expansion height, less surge height. The fluidization process of the two catalysts in the gas?solid fluidized bed were basically similar, including the expansion, bubbles, turbulent and other flow patterns, which appeared successively with the increasing superficial gas velocity. However, the critical velocities during the transition between different flow patterns were quite different. The results showed that the physical parameters of the catalysts affected the flow characteristics considerably. Comparing with the FCC catalyst, the FT catalyst was much stable in each step during the fluidization process, which was benefit to the uniform distribution of the catalyst in the gas–solid fluidized bed. Consequently, the contact performance of the FT catalyst was better than that of the FCC catalyst. Furthermore, with different ratios of bed height to diameter, the turning points of the surge height were related with the flow patterns. Therefore, the relationship between the surge height and the superficial gas velocity could be the estimation basis of the critical velocity in different flow patterns of the turbulent fluidized region.
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