基于晶格限域效应的纳米金属催化剂制备及其催化生物乙醇转化性能研究

Biomass energy, one green energy for sustainable development, can help to alleviate human dependence on non renewable fossil resources. It is of great significance for developing biomass energy utilization technology for promoting the diversification of the energy structure, increasing energy supply, promoting emission reduction and environmental protection. As an important platform of bio molecules, bio-ethanol can not only be used as a fuel, but be converted to a variety of chemical products with high added values. The development of high performance bio-ethanol conversion catalysts and related technology has become the focus of the study...Catalytic technologies have widely been used in many industrial fields such as energy conversion, environmental protection, chemical synthesis, and preparation of materials. Developing catalytic technologies is one of giving priority to the development of China's high-tech industry areas. The study on the heterogeneous metal catalysts has shown that the interaction between the metal active centers and the support can affect the characteristics of the metal surface valence electrons, which has a direct effect on the level of the reactive activation energy and the reaction channel. Recently, it was discovered that the electronic properties of the confined catalytic systems have significant effects on improving the activity and stability of catalyst. The regulation of the catalytic properties on the molecular and atomic level for the nanometal catalysts has been attempted by the confinement effects related to the metal surface, the porous material channel, the carbon nanotube space, and the crystal lattice...The project will be mainly engaged in the design and preparation of nanometal catalysts by lattice-confined reduction from single precursor of layered double hydroxides (LDHs) and their catalytic performance for bio-ethanol conversion reactions, based on the demand for technology progress of the chemical conversion of biomass energy to high value fuel and chemicals technology, and the study on the interaction between the catalytic centers and the support for the heterogeneous metal catalysts. The focus of this project will be on the resolution of three key scientific problems in the fields of catalysis and biomass energy conversion: (1) the effects of confinement microenvironment on the structural and electronic properties of catalytic centers and the related synergistic effect; (2) the formation mechanism of metal active sites and their controllable preparation; (3) the roles of confinement effect on the modulation of catalytic conversion of bio-ethanol into high value fuel and chemicals. The lattice-confined reduction strategy was developed for preparation of several nanometal catalysts such as nickel, cobalt, and iron catalyst, from the single LDHs precursor. Modulation of metal particles aggregation and growth was achieved by regulating the confinement micro-environment of the LDHs precursor. A systematic investigation on the mechanism of transformation of LDHs precursor to obtain metal nanoparticles confined in the remaining metal oxide phase upon lattice-confined reduction at different temperature stages will be carried out. Meanwhile, this project will study the catalytic performance of the resulting metal catalysts for the chemical conversion of biomass ethanol to 1-butanol and acetaldehyde, and investigate the confinement effects on the relationship between the structure of active centers and the catalytic performance. We hope that such a systematic study of design, controllable preparation and catalytic properties of the heterogeneous metal catalysts may provide an evident proof for the control of confinement environment for metal catalysts and catalytic reactions, with the purpose of enhancing the catalytic properties for conversion of bio-ethanol into high value fuel and chemicals.

本项目基于生物质能源化学转化合成燃料及高值化学品的技术进步需求，依托于催化科学技术领域中催化活性位与载体之间相互作用影响规律的研究成果，从限域体系金属活性位结构设计、制备机制及催化性能研究中提炼出三类关键科学问题：（1）限域微环境对催化活性位结构及电子特性的影响及协同效应；（2）金属活性位的形成过程机制及控制制备；（3）限域效应调变生物乙醇分子定向催化转化的作用本质。突破晶格限域还原合成高效负载型镍、钴、铁等纳米金属催化剂材料的关键制备技术；调变限域微环境来调控催化剂粒子聚集、生长及其电子特性；结合理论计算揭示晶格限域结构性质对于金属催化剂表面价电子特性的作用本质；研究金属催化剂在生物质乙醇分子化学转化生成1-丁醇、乙醛等反应中的催化性能，探讨限域体系活性位结构与催化性能之间的构效关系。希望为实现生物质资源的高值转化及限域催化机制研究提供理论及实验基础。

作为一种重要的生物质平台分子，生物乙醇既可以用作燃料，又能够经过化学转化合成多种具有高附加值的化学产品。这样，通过将生物乙醇进行燃料品质提升或者化学转化，为降低乙醇成本并使之能与化石燃料产品在价格上具有竞争优势提供了一条途径。研发高性能的生物乙醇转化催化剂材料及相关工艺成为人们关注的重点。伴随着催化研究发展的进程，特别是新世纪以来，人们发现“限域体系”电子和几何特性对提高催化剂的活性及稳定性具有显著的影响。虽然目前基于限域效应的新型催化剂材料创制及限域效应影响机制等方面的研究业已取得了长足进展，但相关催化活性位与载体之间相互作用研究中仍存在一些重要科学问题。.本项目基于生物质能源化学转化合成燃料及高值化学品的技术进步需求，从限域体系金属活性位结构设计、制备机制及催化性能研究中提炼出三类关键科学问题：（1）限域微环境对催化活性位结构及电子特性的影响及协同效应；（2）金属活性位的形成过程机制及控制制备；（3）限域效应提高生物乙醇分子催化转化活性的本质。项目选择在生物乙醇分子化学转化反应过程中具有重要应用的多相负载型镍、铁、钌等金属催化剂材料作为工作重点，突破了类水滑石LDHs前驱体晶格限域合成负载型纳米金属催化剂材料的关键制备技术；探究了层状前体限域结构的形成、演化和控制机制；提出了制备纳米金属粒子催化剂时LDHs前驱体的“复合限域效应”机制；研究了限域效应提高催化剂粒子的分散及稳定性，控制活性晶面取向生长的本质。同时，采用理论计算的方法揭示层状前体限域结构性质对于金属催化剂电子及几何特性的作用本质，探讨活性位结构与催化性能之间的构效关系。通过解决上述科学问题，有望为实现生物质资源的高值转化，以及基于限域效应的新型催化剂材料的创制研究提供理论及实验基础。