First principles design of novel ammonia synthesis catalysts

Haber Bosch工艺在工业规模上合成氨的发展是20世纪的主要成就之一。它通过提供获得合成肥料的便利途径，可以直接归功于维持全球人口。该工艺是基于纯N2和H2进料流在促进铁基催化剂上的反应。它在高压（100个大气压）和中等温度下运行，整个过程目前占全球能源需求的很大一部分（100个大气压）。在这项研究中，我们正在尝试开发替代催化剂，通过在较低的反应温度下促进反应来节省能源（在热力学上有优势）。所采取的方法将包括计算设计和实验测试的混合，并基于先前对氨合成中表现出有趣活性的金属氮化物催化剂的研究。金属氮化物在其结构中可能含有“活性”氮，而这种晶格氮的反应性可能是其高活性的关键。使用计算模型，将获得对实验结果的理解，并将其扩展到鉴定具有潜在高催化活性的氮化物材料。在平行的实验室实验中，确定的材料将被合成和测试，并将结果反馈到计算模型中，以提供更好的理解。通过这种方式，将确定最佳催化剂配方，并在工业相关的氨合成条件下制备和测试这些配方，并将结果与传统工业应用的铁基催化剂进行比较。

The development of the Haber Bosch Process for the synthesis of ammonia on an industrial scale was one of the major achievements of the 20th Century. It can be directly credited with sustaining the global population through the provision of an accessible route to synthetic fertilizers. The process is based upon the reaction of pure N2 and H2 feedstreams over a promoted iron based catalyst. It is operated at high pressure (>100 atmospheres) and moderate temperature and the process as a whole currently accounts for a significant proportion of global energy demand (>1%). In this research, we are attempting to develop alternative catalysts which will contribute to energy savings by facilitating the reaction at lower reaction temperatures (where there is a thermodynamic advantage.) The approach to be taken will involve a mixture of computational design and experimental testing and is based upon previous studies of metal nitride catalysts which exhibit interesting activity for ammonia synthesis. Metal nitrides potentially contain "activated" nitrogen within their structure and it is the reactivity of this lattice nitrogen which which could be the key to their high activity. Using computational modelling, understanding of experimental results will be obtained and will be extended to the identification of nitride materials of potential high catalytic activity. In parallel laboratory experiments, the identified materials will be synthesised and tested and the results fed back into the computational modelling to provide improved understanding. In this way, optimal catalyst formulations will be identified and these will be prepared and tested under industrially relevant ammonia synthesis conditions and the results will be compared to those from conventional industrially applied iron based catalysts.