摘要
应用X射线衍射(XRD)、程序升温还原(TPR)技术对等体积浸渍法制备的Co-Mo/CNT催化剂进行了表征.采用高压微反装置、以二苯并噻吩为模型化合物,对催化剂进行了HDS活性评价.XRD结果表明:260℃条件下处理催化剂,催化剂的表面物种主要是MoO3,表面物种高度分散;500℃焙烧处理的催化剂的表面物种主要是MoO2,同时在Co-Mo/CNT催化体系中出现了CoMoO3和Co2Mo3O8物种的强衍射峰,高温焙烧时催化剂活性组分在碳纳米管的表面容易聚集形成MoO2等晶体.TPR结果表明:在Co-Mo/CNT催化剂中,表面物种的还原温度低于Co-Mo/γ-Al2O3中物种的还原温度.活性评价表明:催化剂的TPR特性和加氢脱硫活性有很好的对应关系,Co-Mo/CNT具有很高的加氢脱硫选择性,并且活性明显高于Co-Mo/γ-Al2O3催化剂.
In this paper, X-ray diffraction, TPR (temperature programmed reduction) techniques are used to characterize the Co-Mo/CNT catalysts prepared by pore volume impregnation method. The HDS activity and selectivity of catalysts are evaluated using dienzothiophene as model compound at definite temperature and LHSV(liquid hour space velocity/ h^(-1))in high-pressure micro-reactor equipment. The XRD results show that all the active phases are highly dispersed on the carbon nanotube support and the main species are found to be MoO_3 when calcinated at 260 ℃, While the main species are MoO_2, CoMoO_3 and Co_2Mo_3O_8 which congregate to form three micro-crystals when calcinated at 500 ℃ under the atmosphere of N_2. The TPR curves revealed that the active species in Co-Mo/CNT catalytic system are more easily reduced at lower temperature than those dispersed on γ-Al_2O_3 support. The HDS activity evaluation experiments find that there is a good relationship between HDS activity of catalyst and its TPR properties. In the Co-Mo/CNT system, it is found that the Co/Mo atom ratio has deep influence on the HDS activity. It is found that the Co-Mo/CNT catalysts are extremely more active than the Co-Mo/γ-Al_2O_3 in HDS experiments of dibenzothiophene. The Co-Mo/CNT catalyst with atom ratio 0.7 is of the highest HDS activity, while the Co-Mo/CNT catalyst with Co/Mo ratio 0.35 is of very high selectivity (direct desulfurization/hydrogenation of aromatic rings).
出处
《分子催化》
EI
CAS
CSCD
北大核心
2004年第1期41-46,共6页
Journal of Molecular Catalysis(China)
基金
中国石油股份有限公司CNPC集团公司催化重点实验室资助课题(CNPC-KL-2001-05).
