Effects of Cu and K promoter on Fe-based catalysts for Fischer-Tropsch synthesis
助剂Cu、K对F-T合成铁基催化剂作用的表征研究

A series of spherical micron-scale Fe-based catalysts, in which K and Cu promoters are incorporated respectively or simultaneously, are prepared by a combination method of continuous co-precipitation and spray drying technology. The textural properties, reduction performance, phase transformation in reduction and/or carbonization process are studied by means of low temperature N_2 adsorption, MES, XRD, H_2-TPR, CO-TPR and constant temperature reduction in H_2, CO and syngas environment. The results indicate that the addition of K promoter can increase the surface area of Fe-based catalyst and iron species dispersion in catalyst, and reinforce the interaction between Fe_2O_3 and silica. The addition of Cu promoter improves the reduction of catalyst and the formation of Fe_3O_4 phase in H_2 and syngas environment, but Cu promoter favors the formation and stabilization of a-Fe phase in CO environment. The addition of K promoter only will suppress the reduction and/or carbonization of catalyst in H_2-containous environment, but the simultaneous addition of K and Cu promoters can apparently enhance the reduction and/or carbonization in H_2, CO and syngas environment, which shows the synergic effect of Cu and K promoters.