热分解法制备的Co/SiO2催化剂上费-托合成反应性能

摘要

Cobalt based catalysts supported on amorphous SiO2 were prepared through thermal decomposition as well as incipient wetness impregnation. They were characterized by means of TG, XRD, TEM and TPR and used in Fischer-Tropsch (F-T) synthesis. The results indicated that Co/A200-I catalyst prepared by impregnation exhibits high F-T synthesis activity, though cobalt particles in it are in irregular shape. In comparison, the cobalt particles in Co/A200-D catalyst prepared through decomposition are in secondary spherical structure with relatively uniform diameter and the Co/A200～D catalyst exhibits high selectivity to light hydrocarbon in F-T synthesis. The specific surface area of SiO2 support also influences the structure of catalysts obtained. Compared with the Co/A200-D catalyst, Co/A380-D catalyst prepared by decomposition with higher surface area support is more difficult in reduction due to the stronger metal-support interaction; however, Co/A380-D exhibits higher catalytic activity in F-T synthesis, probably due to the higher cobalt dispersion.%以无定形二氧化硅为载体,分别采用浸渍法和热分解法制备了钴基催化剂Co/A200-I和Co/A200-D,采用TG、XRD、TEM和TPR等手段对其进行了表征,并考察了这些催化剂在费-托合成反应中的性能.结果表明,浸渍法制备的Co/A200-I催化剂中钴颗粒没有规则的形状,但却具有较高的费-托合成反应活性;热分解法制备的Co/A200-D催化剂中钴颗粒呈一种球形二次结构,直径比较均匀,对于费-托合成反应具有较高的轻质烃选择性.此外,载体比表面积对催化剂结构也有较大的影响;相对于Co/A200-D催化剂,Co/A380-D催化剂的载体比表面积较大,这使得金属-载体间的相互作用较强而较难还原,但还原后Co/A380-D催化剂拥有较高的钴分散度和较好的反应活性.