Ammonia

Ammonia is the second most transported chemical in the world today, with a global annual trade of around 180 Mtons. The history of the chemical’s generation and widespread utilization is based around demand from global food production, resulting in rapid expansion of the fertilizer industry through the twentieth century. Current widespread utilization of ammonia facilitated by global transportation has been enabled through the significant breakthrough of two German Nobel prizewinners (Fritz Haber and Carl Bosch) in the early twentieth century. Their catalytic Haber–Bosch process enabled the creation of ammonia from its constituent elements on industrial scale for the first time. The chemical can be utilized as a fuel via two main routes: first, by cracking ammonia to recover hydrogen prior to utilization in a combustion system or fuel cell, or secondly by direct ammonia use. Whereas the former requires an additional process penalty, the latter is less well publicized to the inherent difficulties associated with direct ammonia/air utilization, excessive NOx production when unproperly burned, and slow reaction kinetics, resulting in challenges associated with ignition and flame stability. Recent advances on enhanced ammonia combustion strategies have increased the potential of directly fired ammonia utilization or ammonia/fuel mixtures.