Effect of Na₂CO₃ solution treatment on the performance of Ni-Mo/ZSM-5 catalyst in thioetherfication

ZSM-5 zeolites were treated by alkali Na₂CO₃ solution; the effect of treatment temperature and time on the structural feature and physical and chemical properties of ZSM-5 zeolites were investigated. The ZSM-5 samples before and after alkali treatment were characterized by XRD, N₂ sorption, XRF, SEM and NH₃-TPD. With n-butyl mercaptan and isoprene as the model compounds for thioetherfication, the activity of Ni-Mo/HZSM-5 prepared from alkali treated HZSM-5 zeolites with micro- and meso-porous structure were evaluated. The results show that the original zeolite frame structure is reserved after Na₂CO₃ solution treatment; moreover, the performance of the Ni-Mo/HZSM-5 catalyst in thioetherfications is improved and the modification process was gentle and controllable. An appropriate increase of the treatment temperature and treatment time was beneficial to the increase of surface area, meso-pore volume and average pore size, as well as the regulation of the acid properties without affecting the microporous structure. However, excessive long treatment time was disadvantageous to the formation of mesopores and the modulation of acidity. The Ni-Mo/HZSM-5 catalyst from ZSM-5 treated with Na₂CO₃ solution at 90℃ for 5 h exhibits high thioetherfication performance; the conversions of n-butyl mercaptan and isoprene reach 92.36% and 97.33%, respectively.