CoMo／Al_2O_3和CoMo／TiO_2－Al_2O_3加氢脱硫催化剂的研

STUDIES OF CoMo/Al_2O_3 AND CoMo/TiO_2-Al_2O_3 HDS CATALYSTS

研究了ＣｏＭｏ／Ａｌ２Ｏ３和ＣｏＭｏ／ＴｉＯ２－Ａｌ２Ｏ３催化剂的加氢脱硫性能，并用ＬＲＳ，ＸＲＤ和ＴＰＳ等方法表征其表面相结构和硫化行为．结果表明，以ＴｉＯ２－Ａｌ２Ｏ３为担体的Ｍｏ和ＣｏＭｏ催化剂的活性均比相应的Ａｌ２Ｏ３为担体的高；少量Ｃｏ，Ｎｉ助剂的引入可显著提高ＭｏＯ３在担体上的分散度和改进催化剂的活性；Ｃｏ助剂还有降低Ｍｏ物种硫化温度的作用．

he surface structure and the sulfidation behavior of CoMo/Al2O3and CoMo/TiO2-Al2O3 catalysts were studied by LRS, XRD and TPS,and their thiophene hydrodesulfurization (HDS) and cyclohexene hydrogenation (HYD) activities were measured in a fixed-bed reactor with 0.5 g of catalyst at 3.0 MPa H,pressure. The results are as follows:(1) LRS spectra show that crystalline MoO3 bands disappear when a small amount of CoO or NiO is added to Mo/TiO2-Al2()3 samples.It means that CoO or NiO promoter can effectively enhance the dispersion of MoO, on TiO2-Al2O3 carrier. XRD data are consistent with the LRS results, and the CoMoO4 phase on CoMo/TiO2-Al2O3 catalyst is readily formed. (2) The measurement of the activities of the catalysts shows that the activities of Mo/TiO2-Al2()3 and CoMo/TiO2-Al2O3 are always higher than that of Mo/Al2O3 and CoMo/Al2O3. CoO and NiO can greatly improve the HDS and HYD activities of Mo/TiO2-Al2O3 and Mo/Al2O3. The catalyst exhibits the highest activity when Co/Co+Mo atomic ratio is in the range of 0.3～0.5.(3) The sulfidation of Mo/TiO2-Al2O3, and CoMo/Tio2-Al2O3, catalysts is carried out in multi-step including O-S exchange at low temperature, S-H2 reaction and deep sulfidation at high temperature.CoO promoter can make sulfiding peak of Mo species shift to low temperature.