Zr助剂对Co/AC催化剂催化费托合成反应性能的影响

Effect of Zr Promoter on Catalytic Performance of Co/AC Catalyst for F-T Synthesis

采用CO加氢反应、X射线衍射 (XRD)、透射电镜 (TEM )、程序升温还原 (TPR)和程序升温表面反应 (TPSR)等技术考察了Zr助剂对Co/AC催化剂催化费 托合成反应性能的影响 .结果表明 ,还原、钝化后的Co Zr/AC催化剂的XRD谱上只有较弱的CoO特征衍射峰 ;反应 5 0h后 ,催化剂中Co主要以fcc晶相存在 ,同时还含有少量hcp晶相的Co ;加入Zr助剂后Co晶相衍射峰明显减弱 .TEM结果表明 ,15 %Co/AC中Co的平均粒径为 2 0nm ,加入Zr后Co粒径变小 ,15 %Co 6 %Zr/AC中Co的粒径为 10nm .CO加氢、XRD和TEM结果表明 ,加入Zr助剂可以提高活性组分Co的分散度 ,同时催化剂的活性随分散度的增大而增大 .TPR和TPSR实验结果证实了上述结论 .

The effect of Zr promoter on the catalytic performance of activated carbon (AC) supported cobalt catalyst for Fischer-Tropsch synthesis was investigated by means of CO hydrogenation, XRD, TEM, temperature-programmed reduction (TPR) and temperature-programmed surface reaction (TPSR). XRD results showed that the dispersion of Co/AC was enhanced with the addition of Zr. Weak CoO diffraction peaks were observed in the XRD patterns of the reduced and passivated catalysts. However, some peaks ascribed to fcc and hcp Co appeared after 50 h on stream in F-T synthesis, and the peak intensity decreased with the increase in Zr loading. TEM results showed that the average size of Co particles of reduced 15%Co/AC was about 20 nm, while that of reduced 15%Co-6%Zr/AC was 10 nm. Correlating the XRD and TEM results with the catalytic performance, it can be proposed that the higher the Co dispersion of the catalyst was, the higher its activity was. TPR and TPSR results confirmed the above conclusion.