层状硅酸盐水热晶化形成分子筛的第一原理模拟

For their uniform and well-defined pore structure and excellent performance, zeolites are widely used for catalysis, separation, selective adsorption, ion exchange and etc. Most zeolitic materials are synthesized by crystallization with either hydrothermal or solvothermal routes. However, as the crystallization of zeolite is a complex heterogeneous process in harsh condition involving many species, it is hard to investigate it in-situ with current experimental technologies and a generalized understanding to the zeolite crystallization is still challenging. With this proposal, we will theoretically investigate the impact of reaction condition and each species in the reaction system on the structure of resulting zeolite crystal based on their contribution to the total free energy during the crystallization process, to understand the form of existence, the interactions among and the evolution of silicates, aluminates, the structure directing agents, their aggregrations and etc. Taking the hydrothermal crystallization of zeolites from layered silicates and the synthesis of mesoporous zeolites as model systems, we will discuss the impact of reaction condition and each reaction species on the crystallization process based on extensive theoretical calculations. The output of this proposal will benefit the investigations in inorganic synthesis and quantum chemistry and provide guidelines and theoretical insights for the design and controlled synthesis of zeolites with superior properties.

分子筛因为具有均匀有序的孔道结构和优异的性能，在催化、分离、选择性吸附及离子交换等工业领域有应用广泛。目前，分子筛的主要合成途径是水热或溶剂热晶化途径，但由于分子筛晶化是合成条件下多组分参与的复杂多相过程，人们对该过程理解尚不统一。本项申请将从水热体系自由能对晶化过程的影响入手，在分子层次上分析多聚硅铝酸物种、结构导向剂等活性组分的存在状态、相互作用和结构演化规律，从理论上定量证明反应条件和反应体系组成对晶化形成的分子筛结构的决定规律。本项申请将以水热条件下处于亚稳态的层状硅酸盐晶化形成分子筛以及介孔分子筛晶化为模型体系，通过理论计算从热力学和动力学角度讨论反应条件、各活性组分对分子筛晶化过程的贡献和基本作用规律。本项申请的开展将极大丰富无机合成化学和量子化学的研究内容，并为高性能分子筛材料的设计和可控制备提供指导。

分子筛具有均匀有序的孔道结构和优异的性能，并且广泛应用。分子筛主要通过水热、溶剂热、固相晶种导向晶化等途径制备，但由于分子筛晶化是特定合成条件下多组分参与的复杂多相过程，其微观机理存在争议。本项目从水热体系自由能对晶化过程的影响入手，结合理论和实验研究，探讨分子筛晶化的微观机理。项目执行期间，按照申报书所列研究计划，围绕分子筛晶化的微观机理开展工作，在分子层次上分析和讨论了多聚硅铝酸物种、结构导向剂等活性组分的存在状态、相互作用和结构演化规律；从理论上证明反应条件和反应体系组成对晶化形成的分子筛结构的决定规律；探索了将统计热力学分析和微观动力学模拟相结合研究反应气氛下物质结构演化规律的策略；开发了层状硅酸盐为原料制备多种分子筛的绿色合成方法，相关反应物种的稳定性和结构演化规律也在实验机理研究和介孔分子筛形成机理的多尺度模拟中得到了验证。这些工作的开展为高性能分子筛材料的设计和可控制备提供指导提供了参考。