骨架掺杂亚甲基微孔分子筛的干胶粉末晶化法合成及催化应用研究

Organic-inorganic hybrid microporous molecular sieves are one type of newly functionalized materials combining the properties of organic groups and inorganic molecular sieves, which have recently been attracting great attention due to their unique structural features and abilities to manipulate the interaction between the host framework and various organic/inorganic guest species. Based on our previous works, the present project will innovate controllable crystallization mode and strategy to synthesize organic-inorganic microporous molecular sieves with methylene-hybrid framework and variable carbon content under the absence of template or the use of extremely low amount of template (sometimes with seeding crystals), and to resolve the biggest problems of this field, i.e. very low doping amount of organic groups in the frameworks and difficult applications of the relevant hybrid molecular sieves as the catalysts and adsorbents due to the difficult removal of organic templates filled in the pore channels. .Importantly, thus-crystallized materials can directly be treated by simple ion-exchange and applied in the catalytic reactions and adsorptions due to the lack of organic template molecules occluded in the pores. Also, the synthesized solids can be bestowed with excellent Bronsted acid-catalyzed or Lewis base-catalyzed activity comparable to the homogeneous process through post-synthesis modifications like the sulfonation of methlyene groups or the amination of lattice [O]. . Extensively physical and structural characterizations, as well as theoretical computation, will be conducted to deeply reveal the effect of the [C] with lower electronegativity substituting for the [O] with higher electronegativity and incorporating into the framework of molecular sieves on the distribution of network electric charge, ion-exchangeable property and catalytic activity. The adsorption laws of thus-synthesized materials for organic molecules will be carefully investigated to probe the interaction between organic-inorganic hybrid frameworks and guest organic molecules. Furthermore, the present project will deeply study the effect of the pore sizes and pore channel structures on the diffusion of organic molecules and the catalytic activity.

有机-无机杂化微孔分子筛是一类结合了有机基团与无机分子筛性能的新型功能材料,在调控分子筛骨架与客体分子相互作用方面表现优异，近年成为了研究热点。本项目基于前期工作，拟通过创新晶化模式等可控合成策略，在不使用或者仅使用极低量有机模板剂（有些需添加晶种）的条件下，合成骨架有机碳含量可调变的亚甲基杂化微孔分子筛，解决该领域有机碳掺杂量低及由于模板剂移走困难严重影响了材料的应用等难题。杂化分子筛经过简单离子交换后可直接应用于催化反应和吸附过程，并能通过后处理改性等赋予更优异的质子酸及碱催化活性；将对材料进行广泛的物理化学及结构表征，并结合理论计算研究，深入揭示低电负性[C]取代了高电负性[O]进入分子筛骨架后对材料的骨架电荷分布、离子交换性能、催化性能产生的影响；考察杂化材料对有机分子的吸附特性，探索分子筛骨架与客体分子间的相互作用规律，研究孔径大小、孔道结构特征对有机分子扩散及催化反应的影响。

对有机-无机杂化微孔分子筛材料的晶化合成进行了创新，尤其是成功开发了干胶转化晶化法（DGC法），应用于有机-无机杂化微孔分子筛材料的合成取得了显著的进展。改进的干胶晶化法合成亚甲基功能化分子筛过程中，制备的干胶粉末中含有所需量的水分，不再加水作为单独蒸汽源；此方法更有利于有机Si-CH2-Si结构的稳定，保留的骨架碳超过97%，断裂的部分较少。然而，使用有机Si-CH2-Si原料作硅源时，无模板剂的干胶晶化法目前只能晶化出MOR结构，无论加入何种晶种（如ZSM-5、beta、MCM-22等）均无诱导作用，可能由于Si-C-Si进入骨架后它的尺寸更有利于形成MOR孔道结构，这已经被DFT-calculation初步证实了。. 无模板剂条件下，使用传统的DGC晶化法，一步合成了内核为MOR、ANA、GIS沸石，外包裹大量有机基团的毛毛球状有机-无机杂化类沸石材料。其晶化过程将沸石成核、DGC自组装和沸石表面的有机功能化等结合一步完成。对合成的杂化分子筛进行了广泛的结构表征，包括XRD、IR、Raman、BET、TG/DTA、SEM、固体NMR技术等。杂化分子筛经过简单离子交换后可直接应用于催化反应和吸附过程，并能通过后处理改性等赋予更优异的质子酸及碱催化活性。. 所获得的功能材料，在环己酮与乙二醇缩合反应中，在催化苯乙烯、alpha-蒎烯、alpha-甲基苯乙烯与空气的环氧化反应中，在催化苯甲醛与氰乙酸乙酯的Knoevenagel缩合反应中及丙烯腈与伯醇的Michael加成反应，均表现出了显著的催化活性。该课题的研究结果，对功能性催化材料的合成具有指导意义。