基于2:1型蒙皂石族矿物界面可调性质设计苯加氢催化剂

The adjustable surface properties and complete cleavage along the (001) plane of smectites make these layer-structured materials as ideal supports for heterogeneous catalysts especially when the research is focused on interface properties. This project proposal is aimed to develop a type of clay-based catalysts that are to be used in the hydrogenation of benzene. In this project the surface properties of 2:1 smectite which includes functional groups, acid centers, surface charges, isomorphous substitutions and pore structures of smectites, are to be investigated in order to design composite catalysts which are composed with clay minerals, organic ligands or inorganic additives, and noble metals. The catalyst should have features such as long-term stability, high efficiency in converting benzene, and certain selectivity in obtaining cyclohexene. Hybrid films are to be constructed in order to study the surface features by using Langmuir-Blodgett (LB) technique. The clay elementary sheets are to be loaded with ligand molecules and noble metals in the LB deposition. By comparing the hybrid films with bulk materials - clay composites which are to be prepared via solution-based physical adsorption, the new formed chemical bonds, active sites, acidity, effects of inorganic additives or ligand molecules, and tenability in the size of metal nanocrystals are to be investigated with aid of optoelectrochemical characterizations. Key factors are to be sought out in order to get a high selectivity of cyclohexene. The kinetics of benzene hydrogenation is also to be clarified with presence of such type of clay-based catalysts. Theoretical calculations of molecular dynamics (MD) are also to be carried out to analyze the molecular conformation when the H2 or benzene molecules were activated at the surface of clay catalysts. New models or mathematical expressions for asymmetric force field are to be constructed between the elementary clay sheet and adsorbed molecules. Therefore, this study has its significances in designing new types of heterogeneous catalysts as well as finding a strategy of utilizing clay minerals.

粘土矿物以其可调的表面及沿（001）面完全解理特性，为催化剂界面设计提供理想的研究对象。本项目针对2:1型蒙皂石族矿物的表面官能团、酸中心、电荷、类质同象取代及孔道结构等可调性质，考察矿物与配体、添加剂、贵金属的复合过程，以及对催化底物分子的吸附规律，目标是开发出一类长效稳定的粘土矿物基催化剂，用于苯加氢选择性催化反应。拟采用Langmuir-Blodgett及光谱电化学联用技术，获取单片矿物/配体/贵金属杂化膜，结合体相吸附法制备的复合材料，重点研究材料表面成键，活性中心，酸碱性，无机添加剂或有机配体，以及多尺度贵金属纳米晶等调控机制，结合催化反应实验，揭示影响苯加氢催化动力学的关键科学问题。辅以分子动力学计算，构建在非对称力场下单片粘土与催化底物分子间作用模型或修正Dreiding统一力场，实现粘土矿物及分子界面设计与催化性能之间关系式的数学表达，为新型催化材料的设计提供科学依据。

本项目利用2:1型蒙皂石族矿物沿（001）面完全剥离的特性，考察了矿物表面官能团、酸中心、电荷、类质同像及孔道等可调性质，发现了SiO4四面体与AlO6八面体的界面异性，可实现选择性负载。研究了矿物不同界面与配体分子、添加剂、贵金属等复合过程，开发出5类长效稳定的粘土矿物基催化材料。所得催化剂用于苯的选择性加氢，CO2吸附、固载与环状碳酸脂生成及H2O2体系苯甲醇氧化等反应，表现出优异特性。研究中还发现了埃洛石腔体内可负载Pt等催化剂，形成外表面负载，所获复合材料在H2O2-醇体系中具有“自运动”特性，即“喷射型马达催化剂”。该类催化剂能在水溶液、毛细管体系中起到令人意想不到的效果。系统考查了1:1型高岭石，2:1型蒙脱石、皂石、合成锂皂石及以Mg为主的三八面体蛭石，阐明了材料表面对催化性能的构效关系，找到了界面调控设计准则，给出了键型、活性中心、酸碱性、配体分子的调控依据。采用了体相吸附法与LB技术构建了单片矿物杂化膜，借助表面化学、结构学及光谱电化学等手段，给出了界面电子传输以及催化剂对底物分子的吸附规律。最后，项目通过第一性原理计算给出粘土表面吸附模型，获得吸附分子平衡取向与吸附能级，实现粘土矿物与分子界面设计及催化性能之间关系的定量表达，并给出实验验证。项目开发的蒙脱石辅助玄武岩纤维负载催化剂已进入中试放大阶段。项目执行期发表了Adv. Energy Mater.、Langmuir、J. Am. Ceram. Soc.、Chem. Eur. J.、Appl. Clay Sci.、ACS Appl. Mater. Interfaces、Appl. Catal. A&B等多篇论文，申请国家发明专利4件，培养博士生2人，硕士生5人，项目产出多项指标超过预期。项目执行团队承办了“2022年第九届全国矿物科学与工程学术会议（NACMSE -2022，线上）”。