Na_2CO_3溶液处理对Ni-Mo/HZSM-5分子筛硫醚化催化性能的影响

采用Na2CO3溶液对ZSM-5分子筛进行碱处理,考察了处理温度和处理时间对ZSM-5分子筛结构特征和物化性能的影响。利用XRD、N2吸附-脱附、XRF、SEM及NH3-TPD表征对处理前后样品进行分析。以正丁硫醇和异戊二烯组成的模型化合物为原料,对碱处理后含微-介孔HZSM-5分子筛制得的Ni-Mo/HZSM-5催化剂进行硫醚化活性评价。结果表明,Na2CO3溶液处理没有破坏原分子筛晶体形貌,保持微孔结构的同时,适当的提高处理温度和延长处理时间有利于ZSM-5分子筛比表面积、外比表面积、介孔孔容和平均孔径的增大,并调节了酸性质。但过长的处理时间并不利于介孔的生成和酸性的调变。经90℃的Na2CO3溶液处理5 h得到催化剂表现较高硫醚化活性,正丁硫醇和异戊二烯转化率分别可达92.36%和97.33%。由此,Na2CO3溶液处理可提高催化剂硫醚化活性,且改性过程温和可控。

Effect of Na2 CO3 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.