ZSM-5/MOR共生分子筛的合成机理Ⅱ——合成中的相变过程  

SYNTHESIS MECHANISM OF ZSM-5/MORDENITE INTERGROWTH MOLECULAR SIEVES Ⅱ——THE PHASE TRANSITION PROCESS

作　　者：马广伟[1] 张慧宁[1] 姜向东[1] 

机构地区：[1]中国石化上海石油化工研究院,上海201208

出　　处：《硅酸盐学报》2010年第10期1937-1943,共7页Journal of The Chinese Ceramic Society

基　　金：国家"973"计划(2003CB615804);国家自然科学基金石化联合重点基金(20736011);国家科技支撑计划(2008BAF-33B05)资助项目

摘　　要：以相变理论为基础,通过估算溶液表面能、X射线衍射物相分析、扫描电子显微镜形貌观察和能谱分析,研究了合成ZSM-5/丝光沸石(mordenite,MOR)共生分子筛溶液的变化特点、晶体的生长过程。结果证明:ZSM-5分子筛和MOR物相间的相变过程中存在自由能驱动力、相界面、位相关系、惯习面和应变能等明显的固相转变特征。结合液-固、液-液和固-液3种相变机理,建立了ZSM-5/MOR共生分子筛的合成机理为:合成溶液先出现固-液分相,形成富硅相和富铝相,在富硅相中生成ZSM-5,在富铝相中生成MOR;由于ZSM-5分子筛的表面能比MOR大,体系处于亚稳相,在成核生长后期,ZSM-5分子筛通过固态相变过程,逐渐转变为MOR,达到相态平衡。通过实验验证了ZSM-5/MOR共生分子筛合成中3种相变过程的存在及ZSM-5/MOR共生分子筛的生长机理。On the basis of phase transition theory,the characteristics of synthetic ZSM-5/mordenite（MOR） sieves solution,the growth progress of molecular sieves crystals were investigated by estimating solution surface energy,X-ray diffraction,scanning electron microscope and energy spectroscopy analyses.The results show that obvious solid phase transition exists between ZSM-5 and MOR molecular sieves,which are characterized by formation free energy,phase interface,phase relationship,habit plane and strain energy.Together with liquid-solid,solid-solid,and solid-liquid phase transition mechanism,the synthetic mechanism of ZSM-5/MOR can be explained as：the phase separation of solution appears on the first stage;as a result,the solution is separated into silicon-rich phase to produce ZSM-5 and aluminum-rich phase to produce MOR.However,the phases are metastable because the surface energy of ZSM-5 sieves is larger than that of MOR.Thus,on the late stage of nucleation,ZSM-5 sieves transit to MOR gradually until intergrowth phase balance reaches.The above-mentioned explanation is also further proved by our experiments.

关 键 词：共生分子筛 丝光沸石 合成机理 相变 

分 类 号：TQ424[化学工程]