(677g) Lih Mediated Ammonia Synthesis Under Mild Condition

Having a hydrogen content of 17.6 wt% NH₃ is an attractive hydrogen carrier. The key issue for NH₃ synthesis and decomposition is the development of non-noble metal based, highly active and stable catalysts that can be operated under mild condition. With the understanding on the interaction of LiH and Li₂NH with 3d metals or their nitrides, novel catalyst systems, i. e., LiH-3d transition metals for NH₃ synthesis and Li₂NH-3d transition metal for NH₃ decomposition, that have activities surpassing the highly active Ru-based catalysts were developed. The unique chemistry among TM, Li, N and H creates a two-reactive center mediated pathway favouring NH₃ synthesis/decomposition over both early and late 3d transition metals under mild condition, i.e., detectable NH₃ formation rates can be obtained at 150 °C over the Mn-, Fe- and Co-LiH composite catalysts, respectively. The characterization of intermediate phases and surface clusters of the catalysts allow the elucidation of the step-wise reaction pathway and the interpretation of catalytic mechanism.