新型介孔固体酸催化烯基芳香化合物高效清洁合成研究

Alkenylation of arenes with alkynes has been considered as a novel simple, clean and atom-economic approach for synthesizing alkenylaromatic compounds, one of the most important fine chemicals. The alkenylation catalysts are mainly focused on precious metals or organometallic compounds. Due to their high cost and difficult separation, to replace them with acid catalysts is a promising approach. The use of microporous zeolite overcomes the inherent shortcomings of liquid acids, but the low catalytic efficiency, poor selectivity and heavy alkyne-polymerization remain to be resolved. Therefore, this proposed work is, based on the difference in reactivity and molecular size of to fabricate novel and highly-efficient mesoporous solid acid catalysts, and to adjust and control the diffusion of reactants and alkenylated products, activation of alkynes and collision process of arenes with the produced alkenyl cations through tuning the acidic properties, pore-structure and morphology of novel mesoporous solid acids. The purpose is to resolve the open problems in existing solid acid in alkenylation reactions. Various characterization techniques would be employed to reveal the relationship between the catalyst nature and catalytic performance of the fabricated novel mesoporous solid acids. Moreover, the assistance effect of microwave on the mesoporous solid acid catalysts on the alkenylation reactions would also be investigated. The intensification effect of microwave on the catalytic properties of the fabricated mesoporous solid acids for the alkenylation reactions would be discussed via correlating the catalytic properties and the change of nature for the fresh and spend catalysts under the microwave and conventional heating conditions, and also investigating the temperature rise behavior of mesoporous solid acid catalysts in the microwave field. The main objective of this proposed work is to lay a solid foundation for the highly-efficient and clean synthesis of alkenylaromatic compounds.

芳烃与炔的烯基化是合成烯基芳香化合物这一重要精细化学品的简单、清洁、原子经济的新路线。烯基化催化剂多用贵金属或有机金属，存在价格高、分离难等问题，而酸催化则颇具前景。沸石克服了液体酸所固有的一些缺点，但其仍存在底物适用范围窄、催化效率低、选择性差和炔聚合严重的不足。为此，本项目拟针对不同底物反应性质和分子尺寸的差异，构建新型高效的介孔固体酸，通过酸性质、孔结构和形貌的调节并结合微波强化技术的运用以对反应底物和烯基化产品的扩散、炔的活化及芳烃与烯基阳离子之间的碰撞过程进行调控，从而解决现有固体酸催化该反应存在的问题。通过分析介孔固体酸的烯基化催化性能数据并结合催化剂的表征结果，来揭示其构效关系。也将通过对微波和热化学下烯基化反应结果及反应前后催化剂特征变化的对比并结合微波场中固体酸温升特性考察，探究微波对介孔固体酸催化烯基化反应的强化作用及规律。本项目旨在为烯基芳香化合物的清洁生产奠定基础。

烯基芳香化合物作为重要的精细化学品及中间体在医药、染料、农药、香料、新型高分子材料、天然产品等化学工业领域占据显著地位。芳烃与炔的烯基化是合成烯基芳香化合物的简单、清洁、原子经济的新路线。烯基化催化剂多用贵金属或有机金属，存在价格高、分离难等问题，而酸催化则颇具前景。沸石克服了液体酸所固有的一些缺点，但其仍存在诸多问题。本项目针对常规沸石分子筛催化烯基化所存的不足，开展了烯基化用新型固体酸催化剂的构建、催化性能评价和构效关系研究，主要涉及以下几个方面：1）新型载杂多酸催化剂 基于前期研究工作，进一步研究了载体类型、形貌和织构性质的调控；2）新型固体超强酸 探索该类固体超强酸用于烯基化反应的可行性，氧化镧的改性、氧化镧锆的孔结构调控及硫酸化镧锆的担载；3）硅铝酸盐 研究天然埃洛石的处理及其烯基化催化性能，并合成了系列多级孔分子筛，研究了其烯基化催化性能和构效关系。通过TEM、XRD、BET、NH3-TPD、吡啶-IR、TGA、XRF、ICP、XPS等表征手段对反应前后固体酸催化剂进行表征，结合芳炔烯基化催化性能测试，揭示所构筑固体酸催化烯基化的构效关系，并探讨了固体酸的调控规律。通过该研究，开发了性能较为优良的烯基化固体酸催化剂，催化活性和稳定性显著提高，并发现了一些有价值的规律。发现，所构筑的固体酸催化剂的烯基化催化性能显著依赖于固体酸的类型、组成和微结构。除了酸性质，固体酸的织构性质和形貌对其烯基化催化性能影响显著。通过孔道长度的调节，可以加强传质，抑制聚合，显著提高烯基化催化稳定性。此外，还开展了纳米碳的制备与调控研究，从而为新形貌固体酸催化剂的构筑提供硬模板，这为后续开展新颖结构固体酸催化剂的研究奠定了基础。总的来讲，通过本项目研究，制备了系列新型具有较高催化活性和稳定性的烯基化用固体酸催化剂，并发现了一些有价值的反应规律和催化剂调控规律。固体酸催化剂用于烯基化反应合成烯基芳香化合物，清洁无污染、催化活性高、催化剂可以再生，具有美好的工业化应用前景。但是，由于炔烃和形成的烯基芳香化合物均易于聚合，固体酸催化剂抗积炭失活催化稳定性仍有待进一步提高。本项目的研究成果，对烯基芳香化合物清洁合成用新型高效固体酸催化剂的开发具有一定借鉴意义。