Mo/Tio_2-Al_2O_3催化剂加氢脱硫性能的研究

在中压反应装置上以环己烷70w％、环己烯25w％和噻吩5w％混合液为反应物,考察了Mo/TiO_2-Al_2O_3催化剂的噻吩加氢脱硫(HDS)和环已烯加氢(HYD)活性。催化剂采用三种预处理条件:(1)400℃H_2S/H_2硫化;(2)500℃H_2还原;(3)不处理。结果表明,预硫化处理的催化剂活性最高,且HYD/HDS大于1。Mo/TiO_2-Al_2O_3的HYD和HDS的活性总是比Mo/Al_2O_2高。当TiO_2的含量超过单分子层时,不经任何处理的Mo/TiO_2-Al_2O_3催化剂就具有很高的HDS和HYD性能,表明TiO_2-Al_2O_3载体有显著改善Mo催化剂加氢脱硫性能的作用。

Studies on Hydrodesulfurization of Mo/TiO_2-Al-2O_3 Catalyst

Thiophene HDS and cyclohexene HYD activities of Mo/Al_2O_3 and Mo/TiO_2-Al_2O_3 catalysts were studied by using a mixture of cyclohexane (70wt％), eyclohexene (25wt％) and thiophene (5wt％)as reactants. Reactions were carried out under 3.0 MPa H_2 pressure and at 250—350℃.The catalysts were either pretreated in H_2S/H_2 at 400℃, or in H_2 at 500℃, or without pretreatment before reaction. Results show that: (1) HDS and HYD activities are greatly improved in the case of Mo/TiO_2Al_2O_3 catalysts, and the activities of catalysts with two theoretical monolayers of TiO_2 on Al_2O_3 are higher than that of lower TiO_2 contents; (2) pretreatment conditions influence obviously the catalytic activity of HDS and HYD. The activities are in the order of presulfided>prereduced>without any treatment for supported MoO_3 catalysts on Al_2O_3 and on TiO_2-Al_2O_3 with low TiO_2 loading, while catalysts with higher TiO_2 contents exhibit relatively high HDS and HYD activities even without any pretreatment. It is suggested that the presence of TiO_2 on Al_2O_3 surface favors the formation of active Mo species and their sulfidation.