Dinitrogen Activation Using Heterobimetallic Complexes Supported by an Extended Cryptand Ligand

Fertilisers. Detergents. Nylons. All of these products are derived from ammonia, which is produced on a megaton scale every year by the Haber-Bosch process. This is one of the world's most important industrial processes: it is the only commercially viable method for transforming nitrogen from the atmosphere into ammonia. However, the environmental impact of the Haber-Bosch process is huge: between 1-2% of the global energy demand, and 1.4% of global CO2 emissions, are a direct result of this process. Despite over a century of research, no commercially viable alternatives have been developed to mitigate this damage.

One of the reasons that the Haber-Bosch process consumes so much energy is the need to break the very strong triple bond between two nitrogen atoms, followed by the reaction with hydrogen to generate ammonia. This project aims to develop an entirely new method for synthesising ammonia by using a single molecule as a catalyst to break that triple bond and form ammonia, all in one step. The key feature of the single molecule is that it will incorporate two different transition metal atoms. One metal will be responsible for binding and activating nitrogen, whilst the other metal atom will carry out the hydrogenation to form ammonia.

Using two different metal atoms means that each metal can be the best one for the job it needs to do, whereas more traditional metal-based catalysts have to compromise on one (or both) parts of this reaction. By selecting the best metals for the job, the energy demand of the reaction will be substantially reduced. This will translate into lower CO2 emissions and lower energy consumption on a global scale.