Al_2O_3改性Co/SiO_2费托合成催化剂的制备及结构表征

Preparation and configuration of cobalt-based catalyst supported on Al_2O_3 modified SiO_2 for Fischer-Tropsch synthesis

采用溶液浸渍法制备不同含量Al2O3的Co/SiO2-Al2O3催化剂。采用程序升温还原(TPR)、X射线衍射(XRD)、物理吸附(BET)以及原位CO吸附红外光谱(DRIFT)对催化剂进行表征。结果表明:Al2O3的添加导致催化剂比表面积稍有下降,但对孔径分布无明显影响;随着Al2O3负载量的增加,载体表面钴粒子粒径变小,分散度提高,同时还原度逐步降低;Al2O3改性后催化剂表面CO吸附峰位发生蓝移,并且桥式CO吸附峰强度明显增大,说明Al2O3改性后钴催化剂具有更高的表面活性。

Co/SiO2-Al2O3 catalysts were prepared by wetness impregnation method by adjusting the amount of Al2O3. The properties of various catalysts were characterized by in situ TPR, XRD, N2 physical adsorption, and DRIFT. As shown in results, the addition of a small amount of Al2O3 to silica-supported cobalt catalysts decreased BET surface area but the added alumina did not change the pore structure. With the increase of alumina loading, the cobalt particle size and the reduction degree decrease, and the dispersion of supported cobalt increases. On the other hand, the addition of Al2O3 led to the blue shift of the adsorbed CO peak and stronger and broader bridged adsorbed CO peak, which indicates that the addition of Al2O3 to Co/SiO2 catalysts results in higher surface activity.