Bottom up design of a novel CuRu nanoparticulate catalyst for low temperature ammonia oxidation

Ammonia has been considered as a renewable and carbon free energy source. Aside from hydrogen, ammonia is the only carbon-free energy vector for transport application. As 26% of all CO₂ is emitted from transport sector, without reducing the emission from the transport sector, it will be impossible to significantly reduce overall CO₂ emission. Ammonia is the second most produced chemicals in the world. It has the lowest cost per GJ of energy among all the conventional fuels^[1]. It has been described as an important chemical storage of hydrogen that can transform the world to a low-carbon economy. Ammonia can also be produced with no carbon footprint at all using e.g. wind or solar energy. The decentralized small scale ammonia production units developed by Reese et al . and Proton Ventures can be a good way to store electrical energy in liquid chemical. Even though ammonia cracking in combination with low temperature fuel cells have long term potential in automotive applications, in short-term, the most attractive option is direct ammonia combustion. Ammonia is also combusted to generate hydrogen via ammonia cracking and auto thermal reforming. However the challenges of homogeneous ammonia combustion are high ignition temperature, low combustion rate and N₂O and fuel NOx production. So, there is a need to develop new ammonia combustion system. One possible way to avoid these issues is catalytic combustion which has many advantages over conventional non-catalytic combustion, as ignition temperature is decreased and NOx emission is reduced because of the low operating temperature^[11] . The combustion reaction is also easier to sustain for catalytic reaction.

In this study we present a bottom up approach to design a novel core-shell nanoparticulate catalyst of ruthenium (Ru) and copper (Cu). The CuRu catalyst invented in this work has proven to be superior in terms of catalytic activity towards ammonia oxidation compared to both copper and ruthenium. A systematic surface scientific investigation of thin films and supported nanoparticles have elucidated the reasoning behind activity enhancement.