金属含量对Pt-Co/AC催化剂低温苯加氢性能的影响

采用浸渍法制备了活性炭负载的Pt-Co双金属催化剂Pt-Co/AC。探讨了不同金属质量分数(Pt的质量分数0.1%~1.2%，Co的质量分数5.0%~40.0%)对Pt-Co/AC催化剂在70℃时催化苯加氢反应活性的影响。采用差热-热重方法分析了浸渍后样品的热分解过程，采用H₂程序升温还原法考察催化剂的还原性能，采用CO脉冲化学吸附测定催化剂表面活性位点。结果表明，Pt-Co/AC催化剂的加氢活性和表面活性位点均随着Co质量分数的增加而呈现先增加后减少的趋势，当Co质量分数为20%时，催化剂的活性最高；Co质量分数从5%增至40%时，催化剂单位活性位点的活性相近。当Pt-Co/AC催化剂中Pt质量分数在0.3%~1.2%时，其催化加氢活性随着Pt质量分数减少仅略有下降，表明加入少量的Pt即可表现出双金属效应。Pt-Co/AC双金属催化剂在70℃，甚至室温(30℃)时均表现出优异的苯加氢催化活性。

Effect of Metal Loadings on Pt-Co/AC Catalyst for Low Temperature Hydrogenation of Benzene

Activated carbon supported Pt-Co bimetallic catalysts(Pt-Co/AC) were synthesized by impregnation method. The influence of metal contents on the catalytic activity of Pt-Co/AC for benzene hydrogenation was evaluated at 70℃. The investigated metal mass fraction ranges were 0.1%-1.2% for Pt and 5.0%-40.0% for Co in Pt-Co/AC catalyst. Differential thermal analysis-thermogravimetry (DTA-TG), H₂-temperature programmed reduction (H₂-TPR) and pulse CO chemisorption were carried out to study the thermal decomposition and reducibility behaviors and the number of active sites of Pt-Co/AC, respectively. The results showed that the catalytic activities of Pt-Co/AC with different Co contents depended on the active site number. With the increase of Co content the catalytic activity and active sites number of Pt-Co/AC displayed the volcano curves, and reached their maximum value at 20% Co. On the other hand, the catalytic activity of Pt-Co/AC decreased slightly with the decrease of Pt content when the Pt mass fraction ranged between 0.3%-1.2%. It is found that small amount of Pt could enhance the catalytic activity of Pt-Co/AC significantly, demonstrating the excellent performance in benzene hydrogenation at atmospheric pressure and at both 70℃ and room temperature (30℃).