Elucidation of Confined Catalytic Sites and Adsorption Intermediates in Crystalline Porous Structures for Renewable Ammonia Reactions

为了跟上经济的加速发展，同时实现环境的可持续发展，人们迫切需要可再生能源来替代日益枯竭的化石燃料，也迫切需要绿色化学品来替代不可降解聚合物等有害物质。氢是一种很有前途的可再生能源，是绿色化学合成中不可缺少的原料。为了产生大规模应用的氢气，研究人员仍在研究有效的生产程序。考虑到各种建议的化学反应产物，以及储存和运输的限制，氨被认为是通过分解反应产生绿色氢的优越环保来源。氨的生产、储存、运输方法齐全、先进；氨还具有氢密度高的优点；在分解过程中，不会释放出COx化合物。根据以往的研究，在吸热分解过程中，具有多孔结构的催化剂在降低活化能和创造更温和的反应条件（即反应强度）方面起着至关重要的作用。较低的温度和压力)，节省能源。通过催化剂形成的经典路易斯对（CLP）或受挫路易斯对（FLP），也可以实现高的周转频率。对氨反应催化剂的优化研究仍在进行中。因此，该项目将在牛津大学曾德文教授的指导下，研究氨分解的催化剂，以有效地在燃料电池和绿色化学中应用可持续制氢。目前研究的催化剂主要是各种类型的沸石/金属有机骨架（MOFs）。（如果时间允许，其他氨-有机反应也可以在催化剂上进行测试。）本项目对催化位点和吸附中间体在此过程中的行为感兴趣，通过在有限的纳米空间内控制金属原子的程度和类型以及具有特定电荷分布的多孔载体，并试图证明所涉及的催化机制。同时，我们的目标是寻找更好的催化剂设计，以增加催化位点以提高转化效率，并消除稀有元素如钌的使用。在项目中，重要的是在催化测试中收集高质量的衍射数据，并对物种进行现场监测，以研究反应。因此，我们的目标是在光束线I11上对选定的催化反应进行系统的原位研究。随着同步加速器技术的仪器灵敏度的最新进步，使用原位气体细胞和在线质谱仪，独特的实验环境将在这一领域提供竞争优势。戴蒙德光源是这个项目的联合创始人。Sarah Day博士和I11的Chiu Tang教授在SXRD方面拥有直接的专业知识，他们将担任Diamond的主要导师。在结构中定位H2也有助于补充SXPD工作，因此我们计划也使用NPD设施（例如ISIS的Polaris或HRPD）。此外，其他原位技术，即APXPS （Held教授，B07）和原位XAS （Cibin博士，B18）将应用于支持结果。综上所述，该项目将重点研究氨反应的催化行为和催化剂的优化，以产生可持续的氢气，参与质子交换燃料电池和绿色化学循环。该项目属于EPSRC的“能源和脱碳”研究领域。

In order to keep pace with the accelerating economic development, and simultaneously achieving sustainable environment, renewable energy sources are highly demanded to replace depleting fossil fuels, as well as green chemicals to substitute with hazardous substances such as non-degradable polymers. It was found that hydrogen is a promising renewable energy source adopted in fuel cells and an indispensable reactant for synthesizing chemicals in green chemistry. To generate tones of hydrogen for large scale application, researchers are still investigating effective production procedures. Considering products of various suggested chemical reactions, as well as limitations on storage and transportation, ammonia is found to be a superior environmentally friendly source for green hydrogen via decomposition reaction. There has been complete and advanced production, storage and transportation methodologies for ammonia; ammonia also has the advantage of high hydrogen density; and during its decomposition, no COx compound is released. Based on previous studies, during endothermic decomposition, catalysts with porous structures play essential roles in reducing activation energy and creating milder reaction conditions (ie. lower temperature and pressure) which saves energy. High turnover frequencies, via either classical lewis pairs (CLP) or frustrated lewis pairs (FLP) formed by catalysts, can also be achieved. The research on optimization of catalysts for ammonia reactions is still ongoing. For effective sustainable hydrogen generation with applications in fuel cells and green chemistry, the project will therefore investigate catalysts in ammonia decomposition under the supervision of Prof. Edman Tsang at University of Oxford. Catalysts fell into research are dominantly zeolites/metal-organic frameworks (MOFs) of diverse types. (Other ammonia-organic reactions may also be tested on catalysts if time is allowed.) This project is interested in the behaviors of catalytic sites and adsorption intermediates during the process, by controlling the degree and type of metal atoms and porous support with specific charge distribution in a confine nano-space and attempting to justify catalytic mechanisms involved. Meanwhile, we aimed to find better design of catalysts to increase catalytic sites for higher conversion efficiency and to eliminate the use of scarce elements such as ruthenium. In the project, it is important to collect high quality diffraction data during catalytic testing and carry out in-situ monitoring of species to investigate reactions. Thus, we aim to conduct systematic in-situ studies at beamline I11 for selected catalytic reactions. With recent advancement in the instrumental sensitivity of the synchrotron technique using the in-situ gas cells coupled with online mass spectrometer, the unique experimental setting will provide a competitive edge in this area. Dimond light source is the co-founder of this project. Dr Sarah Day and Professor Chiu Tang of I11, who have direct expertise in SXRD will act as main supervisors at Diamond. It is also helpful to locate H2 in the structure to complement the SXPD work, hence we plan to gain access to use NPD facilities too (e.g. Polaris or HRPD at ISIS). In addition, other in situ techniques i.e. APXPS (Prof. Held, B07) and in situ XAS (Dr Cibin, B18) will be applied to support results. To conclude, the project focuses on elucidation of catalytic behviours and optimization of catalysts for ammonia reactions, for the purpose of generating sustainable hydrogen gas involved in proton-exchange fuel cell and green chemistry cycles. This project falls within the EPSRC 'Energy and Decarbonisation' research area.