First principles design of novel ammonia synthesis catalysts

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.

This project will apply computational design of metal nitrides to develop novel ammonia synthesis catalysts. When consideration is given to the very highly energy intensive nature of ammonia synthesis as currently practiced on an industrial scale, the economic and environmental benefits to both industry and society as whole resulting from any improvement is readily apparent. It has been estimated that, globally, industrial ammonia synthesis accounts for more 1% of energy demand.
In order to realise any industrial benefit and to achieve maximum impact, it is necessary to have direct contact with an industrial company with interests related to this area. Accordingly Johnson Matthey Catalysts, a UK-based company which have a major international presence in the area of ammonia synthesis catalysts, (and hence concomitant relationships with a range of industrial ammonia manufacturers and users), are involved as a partner in this project. Under the terms of a non-disclosure agreement, they will provide industrial guidance and also some support in kind. This will include the opportunity to test catalysts under industrially relevant conditions and to benchmark their performance against industrial catalysts. The UCL Business and Glasgow Research and Enterprise departments will ensure effective exploitation of any IP arising from this project.
An international nitrogen activation workshop will be organised and a resultant international network will be established as part of this project and these will ensure dissemination pathways to those with interests in, and the ability to exploit, any outcomes arising. Dissemination of results to the wider academic and industrial community will also be achieved through the traditional routes of publication in high quality international journals and presentations at major international meetings.