Development of Gas-Solid Reactor for Activating Iron-Based Fischer-Tropsch Catalysts

In industries, Fischer-Tropsch technology uses syngas by coal gasification for producing clean oil through some iron-based catalysts, which should be firstly activated from its oxidation state to the reduced state before application. Currently, the reactor for activation of catalysts belongs to some kind of slurry bed with a gas-liquid-solid fluidization system. Due to the existence of liquid between gas and catalysts, the activation rate is affected directly by the liquid resistance. Furthermore, compared with gas-liquid-solid slurry bed, gas-solid fluidized reactor has advantages in aspects of shorting activation time, lowering investments, reducing operating costs, and online make-up, etc. Therefore, the idea of gas-solid fluidization reactor was presented by us for the activation of catalysts. The study of the fluidization behaviors for iron-based Fischer-Tropsch catalysts was carried out on a cold fluidization reactor by using air as fluidization medium, including particle characteristics, the degassing capacity and the distribution of catalysts concentration. The experimental results of fluidization showed that iron-based Fischer-Tropsch catalysts belonged to Geldart A and had an easier ability of fluidization than FCC catalysts. On the basis of fluidization results, a pilot gas-solid reactor for the catalysts activation was built to investigate the affecting factors, such as pressure, superficial velocity of syngas, CO concentration, and so on. The activation experiments on the pilot unit indicated that the greater the pressure the better the activation, and the turbulent state was much better than the bubbling state. The comparison of the activation effect between gas-solid fluidization reactor and gas-liquid-solid slurry bed showed that gas-solid fluidized activated catalyst almost has the same Fischer-Tropsch catalyst performance. The study helps to achieve the process package and promote the commercialization of gas-solid reactor for catalysts activation.