磁性双功能催化剂的构建及甲醇一步合成甲缩醛和甲酸甲酯反应机理研究

Both the dimethoxymethane and the methyl formate are more valuable secondary productions of the methanol. However, in the gas-solid catalytic reaction process of the methanol to form dimethoxymethane and methyl formate, there are the excessive inert gases to be circled and the deep oxidation of methanol will occur in higher reaction temperature. In this project a new method for construction the magnetic bifunctional catalysts was proposed. This is that, firstly, the macro(meso)pore shell layer with the acid sites was coated on the surface of superparamagnetic Fe3O4 core and the macro(meso)pore shell@Fe3O4 magnetic nano particles were synthesized. Secondly, the catalytic activity components of the selective oxidation of methanol, such as Pd and Au, are assembled into the macro(meso)pore shell. Finally, the magnetic bifunctional catalysts, named the catalytic activity components/macro(meso)pore shell@Fe3O4 are prepared. At the same time, the performance of the magnetic bifunctional catalysts for the methanol to form dimethoxymethane and methyl formate in the liquid-solid catalytic reactor will be evaluated. The relationship of the catalytic active components, the acid sites, the reaction mechanism, the recycling properties and the magnetic bifunctional catalysts will be adequately investigated. Actualized this project, the new technology of preparation the magnetic bifunctional catalysts and the catalysis process of the methanol to form dimethoxymethane and methyl format will be formed. This project has an important scientific significance to understand the Pd and Au for the selective oxidation of methanol, the acid sites for the condensation and the esterification reaction, and the reaction mechanism to form dimethoxymethane and methyl formate over the bifunctional catalysts. There is a bright future application for the methanol to dimethoxymethane and methyl formate.

甲缩醛和甲酸甲酯是高附加值的甲醇下游产品。在甲醇合成甲缩醛和甲酸甲酯的气-固催化反应过程中有大量惰性气体要循环，且易发生深度氧化。本项目提出一种新的磁性双功能催化剂制备方法，即在磁性Fe3O4颗粒表面包裹一层具有酸性位的大(介)孔壳，制成大(介)孔壳@Fe3O4磁性微球，再将Pd、Au等组装在大(介)孔壳的孔中，制备出“催化活性组分/大(介)孔壳@Fe3O4核”磁性双功能催化剂。然后在液-固反应器中将甲醇选择氧化、及新生的甲醛（甲酸）与甲醇缩合（酯化）耦合在一起，一步合成甲缩醛和甲酸甲酯，并深入研究催化剂的制备、结构与性能关系、耦合反应机理、磁性回收重复使用等，形成磁性双功能催化剂制备新技术和甲醇一步合成甲缩醛和甲酸甲酯新工艺。项目实施对认识Pd、Au的甲醇选择氧化、酸性位的甲醇缩合(酯化)、以及双功能催化剂耦合机理有重要的科学意义，对实现甲醇合成甲缩醛和甲酸甲酯新工艺有重要的应用价值。

甲缩醛和甲酸甲酯是高附加值的甲醇下游产品，将甲醇催化转化一步合成甲缩醛和甲酸甲酯的关键是即具有甲醇选择氧化催化活性组分、又具有酸性位的双功能催化剂。本项目采用两种方法制备了新型双功能催化剂：在磁性Fe3O4纳米颗粒表面原位合成一层具有酸性位的大(介)孔壳层，再将Pd、Au等催化活性组分组装在大(介)孔壳层孔中，制备出“催化活性组分/大(介)孔壳@Fe3O4核”磁性双功能催化剂；在磁性Fe3O4纳米颗粒表面原位合成一层含有悬挂-NH2的NH2-MOFs@Fe3O4磁性纳米球，然后将Pd、Au离子与悬挂-NH2进行配位络合，再经过焙烧使MOFs分解为具有酸性位的多孔氧化物壳层，Pd、Au节点则被限域在具有酸性位的多孔氧化物壳层中，制备出“单原子金属/多孔酸性氧化物壳@Fe3O4核”磁性双功能催化剂。采用XRD、HR-TEM、XPS、FT-IR等现代分析测试方法表征了催化剂的结构，在液-固催化反应器中评价了催化剂的甲醇一步合成甲缩醛和甲酸甲酯的催化性能，深入研究了催化剂的制备、结构与性能关系、甲醇选择氧化及新生甲醛（甲酸）与甲醇缩合（酯化）的耦合反应机理、磁性回收重复使用等，获得了磁性双功能催化剂制备新技术和甲醇一步合成甲缩醛和甲酸甲酯新工艺。研究工作对Pd、Au等催化活性组分上甲醇选择氧化、酸性位上新生的甲醛（甲酸）与甲醇缩合（酯化）耦合反应机理的深刻认识具有重要的科学意义，对甲醇一步合成甲缩醛和甲酸甲酯新工艺的开发具有很好的应用前景。研究工作申请中国发明专利5件（其中授权2件）；发表学术论文18篇；毕业研究生9名（其中博士生1名）。