This paper sets the new design parameters for the development of low temperature ammonia decomposition catalysts based on readily available cobalt as an alternative to scarce but highly active ruthenium-based catalysts. By using a variety of carbon materials as catalytic supports, we systematically demonstrate that microporous supports capable of stabilising small cobalt crystallites (~2 nm) lead to high catalytic activities compared to bigger nanoparticles. Additionally, the degree of graphitisation of the carbon support has a detrimental effect on the activity of the cobalt (0) active sites, likely due to their potential as an electron donator. Consequently, the addition of electron donating promoters such as cesium substantially decreases the activity of the cobalt catalysts. This relationship deviates from the trends observed for ruthenium-based catalysts with an optimum 3–5 nm size where an increase of the graphitisation degree of the support and the addition of electron donating promoters increases the ammonia decomposition activity.The authors would like to acknowledge the UK Engineering and Physical Science Research Council (grant number EP/L020432/2) and the Doctoral Training Centre in the Centre for Sustainable Chemical Technologies at the University of Bath (grant number EP/K016334/1) for funding, and SASOL UK Ltd for supporting TEB’s studentship. We would also like to thank the Research Catalysis Group at Harwell(RCaH)for access to the TEM microscopy facilities.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.cattod.2016.05.04
