费托合成 Fe基催化剂中铁物相与活性的关系

 采用连续共沉淀和喷雾干燥相结合的方法制备了微球形 Fe 基催化剂, 采用 N2 吸附-脱附、X 射线衍射和穆斯堡尔谱等手段, 考察了催化剂在不同还原条件下铁物相的转变, 并在浆态床反应器中评价了催化剂的费-托合成 (FTS) 反应性能. 结果表明, Fe 基催化剂在合成气气氛下首先从α-Fe2O3 转变为 Fe3O4, 然后转变为铁碳化物 (FexC); 还原压力的增大有利于 α-Fe2O3 向 Fe3O4 的转变, 而抑制 Fe3O4 向 FexC 的转变; 还原空速的增加则促进 Fe3O4 转变为 FexC. 催化剂的 FTS 反应活性随着催化剂中 Fe3O4 含量的增加而逐渐下降, 而随着 FexC 含量的增加而逐渐上升.

Relationship between Iron Phase and Activity of Iron-Based Fischer-Tropsch Synthesis Catalyst

A typical Fe-based catalyst for Fischer-Tropsch synthesis (FTS) was prepared by a combination method of continuous co-precipitation and spray-drying technology. The study was undertaken to investigate the iron phase transformation under different pretreatment conditions and the influence of phase structure on FTS activity of the catalyst in a stirred tank slurry reactor. N2 adsorption-desorption, X-ray diffraction, and Mössbauer effect spectroscopy were used to characterize the catalyst. It was found that α-Fe2O3 in the fresh catalyst was reduced first to Fe3O4 and then converted to iron carbides (FexC) in the syngas atmosphere. Increasing the reduction space velocity promoted the reduction and carburization of the catalyst. Higher reduction pressure facilitated the reduction of α-Fe2O3 to Fe3O4 but suppressed the carburization of magnetite. During FTS the catalytic activity decreased gradually with increasing magnetite content and decreasing iron carbide content.