调整双季铵盐表面活性剂与单季铵盐表面活性剂的使用量,通过协同晶化的方式合成了高结晶度、高介孔容的薄层ZSM-5沸石.利用XRD、XRF、SEM、TEM、NH3-TPD、低温氮气物理吸脱附以及27Al MAS NMR对沸石样品进行表征,并评价其甲醇制丙烯反应(MTP)催化性能.结果表明,薄层沸石的b轴厚度随着双季铵盐表面活性剂使用量的减少而增加,适量的单季铵盐表面活性剂的加入可以起到协同晶化的作用,能够有效稳定胶束,从而调控沸石的形貌.优化2种季铵盐表面活性剂的使用量所得薄层ZSM-5沸石的比表面积和介孔孔容都有所增加,在甲醇制丙烯反应中的活性稳定性也得到较大改善.此外,协同晶化的方式减少了双季铵盐表面活性剂的使用,有利于降低薄层ZSM-5沸石的合成成本.
Abstract
Nanolayered ZSM-5 zeolites with high crystallinity and large mesopore volume are prepared through cooperative synthesis mode by adjusting the dosages of bi-quaternary ammonium surfactant and mono-quaternary surfactant,and characterized in detail by means of XRD,XRF,SEM,TEM,NH3-TPD,low-temperature nitrogen physisorption,and 27 Al MAS NMR.Furthermore,their catalytic performance for methanol-to-propylene reaction(MTP)is evaluated.It is shown that C16-6-6 is able to synthesize nanolayered ZSM-5 effectively,but the b-axis thickness of nanolayered ZSM-5 zeolite inevitably increases as the dosage of C16-6-6 decreases in the gel.It is found that the addition of an appropriate amount of low-cost C16-3 can play a synergistic role during the crystallization,which can effectively stabilize the micelles and tune the thickness of the nanolayered ZSM-5 zeolites.Through optimizing the dosages of C16-6-6 and C16-3 in the synthesis,the specific surface area and mesopore volume of the nanolayered zeolites prepared increase,and the stability of catalytic activity of the resulting zeolite samples in methanol-to-propylene reaction is also significantly improved.Most importantly,the cooperative synthesis reduces the using amount of expensive C16-6-6,which is beneficial to reduce the synthesis cost of nanolayered ZSM-5 zeolite.
维普
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