SAPO-34分子筛晶化机理及晶化动力学研究

对SAPO-34分子筛晶化过程中预相形成、诱导期内晶核生成、晶体生长和晶化过程的研究进行综述。SAPO-34分子筛晶化过程首先形成不稳定的层状预相结构,进而发展为具有有序排列晶格骨架的晶核。结晶热力学控制晶相结构,晶化动力学控制晶体成核和生长速率。影响晶化动力学的关键因素是温度和浓度,成核速率和晶体生长速率互相竞争控制晶粒大小。晶化过程的Si取代机理和Si分布影响分子筛酸性。晶化动力学研究结果表明,温度升高,结晶速率增加,成核时间缩短。

Development in crystallization mechanism and crystallization kinetics of SAPO-34 molecular sieves

The pre-phase formation,the crystal nuclei generation in the induction period,crystal growth and the termination of crystallization during the crystallization process of SAPO-34 molecular sieves were summarized.A firstly formed layered prephase evolved into orderly lattice frame of crystal nucleus.Crystalline thermodynamics controled phase structure and crystallization kinetics controled the rates of the crystal nucleation and crystal growth.The key influential factors of the crystallization kinetics were the crystallization temperature and concentration;the competition of the nucleation rate and crystal growth rate determined the crystal size.The Si substitution mechanism and Si distribution during the crystallization process had influence on the acidity of the molecular sieve.The research results of crystallization kinetics showed that the crystallization rate increased and the nucleation time was shortened with the increase of the crystallization temperatures.