Publications Details

Solar-Thermal Ammonia Production Via a Nitride Looping Cycle [Slides]

Ambrosini, Andrea A.; Bush, Hagan E.; Ermanoski, Ivan; Gao, Xiang (Michael); Loutzenhizer, Peter; Miller, James E.; Stechel, Ellen B.

Solar Thermal Ammonia Production has the potential to synthesize ammonia in a green, renewable process that can greatly reduce the carbon footprint left by conventional Haber-Bosch reaction. Ternary nitrides in the family A₃B_xN (A=Co, Ni, Fe; B=Mo; x=2,3) have been identified as a potential candidate for NH₃ production. Experiments with Co₃Mo₃N in Ammonia Synthesis Reactor demonstrate cyclable NH₃ production from bulk nitride under pure H₂. Production rates were fairly flat in all the reduction steps with no evident dependence on the consumed solid-state nitrogen, as would be expected from catalytic Mars-van Krevelen mechanism. Material can be re-nitridized under pure N₂. Bulk nitrogen per reduction step average between 25 – 40% of the total solid-state nitrogen. Selectivity to NH₃ stabilized at 55 – 60% per cycle. Production rates (NH₃ and N₂) become apparent above 600 °C at P(H₂) = 0.5 – 2 bar. Optimal point of operation to keep selectivity high without compromising NH₃ rates currently estimated at 650 °C and 1.5 - 2 bar. The next steps are to optimize production rates, examine effect of N₂ addition in NH₃ synthesis reaction, and test additional ternary nitrides.