一维孔道沸石多形体控制合成、结晶形态调控及催化性质

The stacking of the same subunit of the zeolite can form the polymorphs of similar framework but with different spatial symmetry, which often causes the differences of their morphology, active sites and fine microporous structures, and thereby the serious difference of the catalytic and diffusion properties. Aimed at this challenging and significant field, this project will focus on the development of new strategies and theory for controllable fabrication and catalytic application of novel structured zeolite polymorphs, especially on those with 1-dimensional porous frameworks, on the basis of our recent researches and new observations in literatures. We try to rationally design series organic structure-directing-agents (OSDAs) with special rigid heterocycles and fexible carbon chains, and explore the host-guest effects and the directing regularity of their charge density and hydrophilic/hydrophoric features on aluminosilicate aggregation and framework formation. The frameworks of some end member polymorphs and their hybrids with defined ratio and subunit distribution would be obtained from the deliberately prepared gel system with the aid of the pre-designed OSDA and/or seeds under the hydrothermal and microwave-assisted hydrothermal conditions. And the ordered hybrid polymorph crystals of zeolites with defined spatial symmetry, morphology and pore structures will attempt to be developed. We will also attempt to deepen the understanding of the fine effects of the special active sites, framework defects, pore size and its intersection manner in polymorphs on the spatial limitation and synergy for reactants and active intermidiates. On the basis of the spacial active sites within the confined nanoporous architectures of these polymorphs, the new concepts would be harvasted on the catalytic mechanism and fine structure-property relationship of zeolite framework, which will promote to develop new ideas on zeolite catalyst designing both for energy and for chemical conversions.

沸石相同构筑单元的不同堆垛将形成结构类似、但空间对称性不同的多形体结构，往往造成其结晶形态、活性位微环境、孔道结构及贯通性等精细结构的差别，直接导致其催化和扩散性能的重大差异。项目瞄准这一既有挑战，又具有重要理论和实用价值的领域，以一维孔道沸石多形体结构为模型，基于我组前期在沸石领域研究结果，结合理论模拟，试图发展沸石多形体催化材料控制合成新路线和理论。将通过特定结构刚性杂环和柔性链共存的多环季铵盐衍生物模板剂设计，结合过程控制，探索其与硅铝聚集态的主客体作用规律、骨架电荷及亲疏水性对沸石骨架的导控规律；以之为指导，实现沸石多形体骨架选择性合成，发展可控组成和空间分布、具有特殊结晶形态和孔结构的新型沸石多形体杂化结构；针对重要能源和化学品的催化需求，解决多形体特殊活性位微环境和骨架缺陷、孔道贯通性等精细结构对客体分子及过渡态的空间限制和协同催化作用，形成对催化机理的新认识，发展新催化材料。

项目的核心思路在于结合近年来文献对沸石多形体精细结构的认识，基于本实验室在纳米沸石及多形体控制合成的初步结果，通过特殊结构模板剂设计、特定晶面的晶种介入及其与硅铝凝胶相互作用研究，实现不同孔道结构和结晶型态多形体和形貌的的控制合成，探索其不同杂化堆垛所形成的特殊活性位和孔道微环境作用规律，为发展精细结构可控的沸石催化剂奠定基础。根据这一指导思想，项目对多种多环季铵盐衍生物模板剂结构设计及其对沸石骨架的导控规律、沸石材料的多形体空间堆垛方式控制及演化规律、特殊形貌沸石结晶形态和孔道性质的调控，及其在大分子和扩散控制的催化反应构效关系等关键科学问题上取得了规律性的新认识。实现了多种多形体堆垛方式沸石杂化结构和特殊形貌介观结构沸石的控制合成，表征并确定了一维孔道沸石多形体孪生或组装单元的位错形态及其独特的介微孔结构，丰富和发展了基于晶种及模板导向的沸石介观晶体非经典晶化机理，揭示了具有等级结构沸石催化剂催化反应特征和规律。并结合沸石合成所需要的复合活性位的创制要求，对相关涉氢转化的活性相进行了初步探索。基于以上研究，先后在Chemical Society Reviews、Angewandte Chemie International Edition、Energy and Environmental Science、Chemistry of Materials、Journal of Materials Chemistry A、Chemistry -a Europe Journal、Catalysis Science and Technology、Chemcatchem等杂志发表标注论文24篇，部分有实用意义的创新成果申请专利8件，创制了适合大分子能源催化及精细化学品转化的新结构沸石催化剂近10种。博士研究生和硕士研究生毕业9名，目前在读10名。博士后出站3人，2名青年教师或博士毕业生晋升为副教授，1名青年老师获得上海市科委扬帆计划人才基金。项目负责人及主要参与人员参加国际分子筛会议8人次，开展学术交流。本研究不仅为沸石晶化规律和特殊形貌或介微孔复合结构沸石的发现和发明提供了基础，而且也对多种结晶材料形成过程认识和多组分复合分子筛功能材料制备策略，拓展分子筛催化剂的性能和反应适应性提供了实验和理论根据。