pH刺激响应“蛋黄-蛋壳”型介孔纳米反应器的构筑及其对苯甲醇选择性氧化反应的调控

Benzaldehyde is an important chemical and pharmaceutical intermediate and selective oxidation of benzyl alcohol is a main method to obtain benzaldehyde. To overcome the problems in this transformation, such as low activity of catalyst and poor selectivity for benzaldehyde, the pH-responsive yolk-shell mesoporous catalytic nanoreactors will be prepared via a modification of pH-responsive polymers on the mesoporous shell of yolk-shell nanoreactor with Pd or Au cores. The catalytic selectivity of oxidation to benzaldehyde will be maintained on a high level by effective close of the nanochannel, which was stimulated by trace benzoic acid generated in the oxidation as the by-product. The catalytic activity of nanoreactor in the oxidation of benzyl alcohol to benzaldehyde will be improved by the separation of active metal species and polymer, expanding the pore size of the mesoporous shell and the multi core of the active metal species. The relationships between nanoreactor and its good catalytic performance will be revealed based on necessary characterizations. In addition, a set of design and preparation methods of pH-responsive nanoreactors with tunable catalytic performance will be established. The research of those new type pH responsive mesoporous nanoreactors would be beneficial to enhance the synthetic efficiency of alcohol oxidation, and has important scientific significance and potential for broad applications.

苯甲醛是一种重要的化工和医药中间体，而苯甲醇的选择性氧化是制备苯甲醛的重要方法。针对目前苯甲醇氧化反应中存在的催化剂活性和选择性偏低的问题，本课题拟将“蛋黄-蛋壳”型介孔纳米反应器的壳层进行pH刺激响应性聚合物修饰，构筑以Pd或Au为活性组分的pH响应“蛋黄-蛋壳”型介孔纳米反应器。将利用在苯甲醇氧化反应中生成的微量苯甲酸，使反应器周围环境pH值下降的特点，刺激介孔外壳孔道自动关闭，终止反应进程，从而使氧化反应保持高的苯甲醛选择性。将通过避免金属活性组分与聚合物接触、适当扩大介孔外壳的孔道尺寸和金属活性组分的多内核化，提高反应器在苯甲醇氧化反应中的催化活性。将通过必要的表征手段研究反应器的纳米结构、聚合物性能与其高选择性和高活性的关系，建立一套具有高活性pH响应介孔纳米反应器的制备方法，其研究成果将有益于提高醇类催化氧化反应的合成效率，具有重要的科学意义和应用价值。

在环境条件的刺激作用下调控催化反应效率，具有非常重要的学术意义和应用价值。基于单宁酸分子与金属离子和多种官能团的反应特性，我们首先制备了两种生物多酚类化合物单宁酸修饰的埃洛石纳米管，得到具有温度响应行为的金纳米催化剂。采用粉末X-射线衍射、透射电子显微镜等表征手段对所制备催化剂进行了较为系统的表征，确定了催化剂的纳米结构和形貌，重点考察了温度对催化性能的调控作用，给出了催化剂纳米结构与调控作用之间的规律性认识。我们还通过Debus-Radziszewski反应快速合成了含咪唑鎓离子的有机多孔聚合物，并通过固体核磁、CO2吸脱附等手段确定了有机多孔聚合物的纳米结构和组成成分，重点研究了咪唑鎓离子和聚合物骨架中的三嗪单元对钯金属纳米粒子的协同稳定作用，揭示了碱性位点与活性位的协同作用对苯甲醇氧化反应的活性和选择性的提升作用。此外，我们还在炔类化合物和苯酚的选择性加氢领域取得进展。以上研究成果在Journal of Catalysis等国内外学术期刊上共发表研究论文9篇，申请发明专利1项，获得1项河北省科技进步一等奖，为高性能环境刺激响应催化体系的设计和可控制备及其在选择性催化反应中的应用奠定了基础。