Publications Details

Solar Ammonia Production via Novel Two-step Thermochemical Looping of a Co₃Mo₃N/Co₆Mo₆N pair [Slides]

Gao, Xiang; Ermanoski, Ivan; De La Calle, Alberto; Ambrosini, Andrea A.; Stechel, Ellen B.

Ternary nitrides in the family A₃B_xN (A=Co, Ni, Fe; B=Mo; x=2,3) identified and synthesized. Experiments with Co₃Mo₃N in Ammonia Synthesis Reactor demonstrate cyclable NH3 production from bulk nitride under pure H₂. Production rates were approx. constant in all the reduction steps with no evident dependence on the consumed solid-state nitrogen up to formation of 661. Material can be re-nitridized under pure N₂ (or 10% H₂/N₂). Bulk N utilization per reduction step averaged between 25 – 40% of the total (2-3 hours). Rate equations and parameters extracted from data. NH₃ selectivity exceeds gas phase equilibrium at higher temperatures (in a large excess of H₂). Selectivity begins to decrease significantly above 650 C, N₂ production rapidly increases above 650 C seemingly due to reaction that is zero order in H₂ (thermal reduction of the nitride?). Poised to begin the systematics studies of relationships between materials and reactions.