二氧化锆助剂对碳纳米管负载钴基催化剂费-托合成催化性能的影响

Effect of ZrO_2 Promoter on the Performance of Carbon Nanotube Supported Cobalt Catalysts in Fischer-Tropsch Synthesis

通过浸渍法制备了碳纳米管负载的钴基催化剂,考察了助剂ZrO2的加入方式对催化剂的费-托合成催化性能的影响.采用透射电子显微镜、氮气物理吸附脱附、X-射线衍射、H2-程序升温还原、X-射线光电子能谱等方法对催化剂进行了表征,并在固定床反应器上对催化剂的费-托合成反应性能进行了测试.结果表明:对于先浸渍钴后浸渍锆或者钴和锆同时浸渍的催化剂,ZrO2的加入提高了钴的分散度;但是先浸渍钴后浸渍锆,ZrO2覆盖了部分钴的表面,使得此种催化剂表现出最低的反应活性.先浸渍锆后浸渍钴的催化剂的钴颗粒虽然较大,但是催化剂中表面钴原子的密度最大,从而表现出最高的反应活性.

A series of carbon nanotubes supported cobalt catalysts were prepared by impregnation method.The catalysts were characterized with TEM,BET,XRD,XPS,H2-TPR and the Fischer-Tropsch synthesis activity tests were carried out in a fixed-bed reactor.The results illustrated that for the catalysts which cobalt was added prior to ZrO2 or cobalt and ZrO2 were added at the same time,the addition of ZrO2 increased the dispersion of the cobalt.The catalyst with added cobalt prior to ZrO2 exhibited the lowest activity.It may be that the impregnated Co prior to the ZrO2 partly covered the Co active site.The catalyst added ZrO2 prior to cobalt exhibited the highest activity,it is due to the highest density of cobalt atoms on the catalyst surface.