ZSM-35沸石原位固相转化法合成过程控制

Control of process for synthesis of ZSM-35 zeolite by in-situsolid phase transformation method

以乙二胺(EDA)为模板剂,采用原位固相转化法合成了ZSM-35沸石,并通过XRD对沸石晶化过程中的影响因素和晶化机理作了详细考察。结果表明,制备ZSM-35沸石适宜的硅铝摩尔比为21<n(SiO2)/n(Al2O3)<37;Na+与模板剂EDA协同作用,共同对ZSM-35沸石起着结构导向作用;延长晶化时间,ZSM-35沸石容易向ZSM-5沸石转晶,合成ZSM-35沸石合适的晶化时间为14～21 h。对晶化机理的考察表明ZSM-35沸石的合成过程具有固相机理的特征,并且由于ZSM-35沸石与ZSM-5沸石具有相同的次级结构单元,在晶化过程中容易发生转晶。

Using ethylenediamine （EDA） as template agent, ZSM - 35 zeolite was prepared by in - situ solid phase transformation method. The influences on crystallization process as well as crystallization mechanism were investigated in detail by XRD method. Results showed that the proper silicon - aluminum molar ratio n （SiO2）/ n（A1203 ） for synthesis of ZSM -35 zeolite is 21 - 37; both Na^＋ and EDA play a cooperative structure - orientation role in the synthesis of ZSM - 35 zeolite; suitable time for crystallization is 14 - 21 h, while extension of crystallization time tends to change ZSM - 35 zeolite into ZSM - 5 zeolite. Results of study on crystallization mechanism indicated that the synthesis process displays features of solid phase crystallization mechanism. Since both ZSM - 35 zeolite and ZSM - 5 zeolite have same secondary structural units, they are easily to transform each other in the crystallization process.