X型沸石粉体的水热制备与表征

HYDROTHERMAL PREPARATION AND CHARACTERIZATION OF ZEOLITE X POWDER

以酸处理红辉沸石为主要原料 ,采用水热法制备了X型沸石粉体。利用XRD ,SEM ,IR等手段研究了水热制备各阶段反应体系中X型沸石成核与晶体生长情况。实验结果表明 :反应混合物的室温陈化是制备纯X型沸石的关键 ,水热反应 6h是制备X型沸石的最佳晶化时间 ,所制得的X型沸石粉体晶形完整 ,粒度 2～ 3μm ,且分布均匀。X型沸石晶粒的生成经历了前驱物溶解 ;硅 (铝 )氧四面体、多元环、β笼等结构的形成 ;成核并形成纳米粒子 ;纳米粒子的聚合生长 ;微米晶粒的继续长大等阶段。X型沸石晶体的表面结构花纹是 β笼四面体在各个面族上叠合的轨迹 ,与 β笼四面体的联结方向相互对应。β笼四面体在各个面族上联结的稳定性顺序为 {1 0 0 } <{1 1 0 } <{1 1 1 } ,因此 ,X型沸石晶体的结晶习性与

Taking acid-treated stellerite as main material, zeolite X powder was prepared by hydrothermal method. The nucleation and crystal growth process of zeolite X in hydrothermal condition were characterized by XRD, SEM and IR. The results show that zeolite X powder with uniform granularity of 2-3 μm in well-proportioned distribution and intact crystal shape can be obtained. The aging of the reaction mixture at room temperature is key to prepare zeolite X. The best reaction time of hydrothermal preparation is 6 h. The formation stages of zeolite X crystal undergo the dissolution of feedstocks and formation of [Si-O4]4-, [Al-O4]5- tetrahedra, multi-member rings, β cage structure et al. The crystal nucleus and nano-particles form and the nano-particles aggregate and grow. Then the crystallites continuously grow up. The surface structure patterns of zeolite X crystal are the superposition tracks of β cage tetrahedra on every crystal face family, and corresponded with the coupling direction of β cage tetrahedron mutually. The sequence of the coupling stability of β cage tetrahedron on every crystal face family is {100}<{110}<{111}. Thus the crystal habits of zeolite X are intimately related with the coupling direction of β cage tetrahedron in crystal and its coupling stability on every crystal face family.