Computational Studies of Ambient Catalytic Dinitrogen Reduction by Electropositive Metal Tetraphenolate Complexes

正电金属四酚盐配合物环境催化二氮还原的计算研究

• 批准号: EP/X042049/1
• 负责人: Nik Kaltsoyannis
• 金额: $ 63.07万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX042049%2F1
• 关键词: Computational; Studies; Ambient; Catalytic; Dinitrogen

The worldwide industrial catalytic conversion of nitrogen to millions of tons of ammonia per annum is a starting point for the production of pharmaceuticals, plastics, fine chemicals and fertiliser. The latter has enabled the lives of around 3 billion people and addresses the United Nations global sustainable development goal #2: zero hunger. The high pressure/temperature Haber-Bosch (HB) process that converts nitrogen and hydrogen to ammonia, known as the nitrogen reduction reaction (N2RR), is perfectly optimised but still very energy intensive. Small scale, low-energy N2RR reactions, including to products other than ammonia, would be complementary to the HB process. They would also improve energy justice by allowing isolated communities to generate their own fertilisers or amines, and potentially facilitate off-world food production. Furthermore, ammonia has the potential to replace fossil fuels as an energy carrier, as it is energy dense and compatible with current infrastructures and fuel cell technologies. However, its incorporation into renewable technologies demands further understanding and better catalysts.Professor Polly Arnold, from the University of California at Berkeley and the Project Partner on this proposal, has recently reported the synthesis and characterisation of molecular uranium and thorium complexes that can convert nitrogen to ammonia at room temperature and pressure, and the first catalytic conversion of dinitrogen into a secondary silylamine by any metal. She has now extended this work to cerium and samarium analogues - the first non-radioactive f-block N2RR catalysts. All of these molecules feature two metal atoms, held in place by two tetraphenol-arene (mTP) ligands. Arnold has also synthesised d-block analogues using titanium and zirconium, which again can effect catalytic conversion of nitrogen to secondary silylamines, and uranium and lanthanide compounds containing two metals but only one mTP ligand, some of which are also effective catalysts. Work is ongoing in Arnold's laboratories to optimise this chemistry, and extend it to other metals, including the very abundant s-block elements calcium, strontium and barium. The proposed research is a comprehensive programme of computational quantum chemistry in the laboratory of Principal Investigator Kaltsoyannis to link synergistically with, and guide, Arnold's ongoing experimental development of new bimetallic homogeneous catalysts for the conversion of nitrogen to ammonia, and secondary or tertiary amines, with particular emphasis on furnishing detailed mechanistic and electronic structural insight. Kaltsoyannis and Arnold have collaborated on many previous projects, and have made important and well-received contributions to f and d block chemistry. Arnold's earlier report of uranium and thorium N2RR catalysts included quantum chemical analysis of the reaction mechanism, and the combination of experiment and computation was essential to the success of that work. The proposed combination of experiment and theory will yield new N2RR chemistry and catalysts, and deep insight into both mechanism and electronic structure. It will deconvolute the roles of the alkali metal reductant, mTP ligand and the Lewis acidic f-, d- and s-block metals to understand the path of the electrons to the metal bound nitrogen, and their subsequent behaviour. In so doing, it will also make fundamental contributions to understanding the role of d and f orbitals in bonding, including the interplay of these orbitals in f block chemistry. It is also anticipated that significant success in catalysis arising from the target compounds will stimulate further advances in the field of electropositive d block catalysis.

全球氮将氮转化为每年数百万吨氨的催化转化是制药，塑料，细化学物质和肥料的起点。后者使大约30亿人口的生命能够解决联合国全球可持续发展目标＃2：零饥饿。将氮和氢转化为氨（称为氮还原反应（N2RR））的高压/温度HABER-BOSCH（HB）工艺经过完美优化，但仍然非常精力充沛。小规模的低能N2RR反应，包括氨气以外的产品，将与HB过程互补。他们还将通过允许孤立的社区产生自己的肥料或胺，并有可能促进北部粮食生产来改善能源正义。此外，氨可能会替代化石燃料作为能量载体，因为它与当前的基础设施和燃料电池技术兼容。 However, its incorporation into renewable technologies demands further understanding and better catalysts.Professor Polly Arnold, from the University of California at Berkeley and the Project Partner on this proposal, has recently reported the synthesis and characterisation of molecular uranium and thorium complexes that can convert nitrogen to ammonia at room temperature and pressure, and the first catalytic conversion of dinitrogen into a secondary silylamine by any metal.现在，她将这项工作扩展到了铜和类似物 - 第一个非放射性F-block N2RR催化剂。所有这些分子具有两个金属原子，由两个四烯醇 - 丙烯（MTP）配体固定在适当的位置。 Arnold还使用钛和锆合成了D块类似物，这再次可以影响氮转化为二烯酰胺的催化转化，以及铀和灯笼化合物，其中含有两种金属，但只有一种MTP配体，其中一些也是有效的催化剂。阿诺德（Arnold）的实验室正在进行工作，以优化这种化学性质，并将其扩展到其他金属，包括非常丰富的S块元素钙，锶和钡。拟议的研究是在首席研究者Kaltsoyannis实验室中进行计算量子化学的综合计划，以与Arnold进行协同连接，并指导Arnold正在进行的新型双金属均质催化剂的实验开发，以转化氮气，以及对氨或二级或型构建机构的转化，并具有详细的详细信息，并构成了材料的构造。 Kaltsoyannis和Arnold已在许多以前的项目上进行了合作，并为F和D块化学做出了重要且受欢迎的贡献。阿诺德（Arnold）早期关于铀和N2RR催化剂的报告包括对反应机制的量子化学分析，实验和计算的组合对于该工作的成功至关重要。提出的实验和理论的组合将产生新的N2RR化学和催化剂，并深入了解机理和电子结构。它将否定碱金属还原剂，MTP配体和刘易斯酸性F-，D和S块金属的作用，以了解电子对金属结合的氮的路径及其后续行为。这样一来，它也将对理解d和f轨道在粘结中的作用（包括这些轨道在F块化学中的相互作用）做出基本贡献。还可以预见，靶化合物引起的催化成功取得了重大成功，将刺激电阳性D块催化领域的进一步进步。