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Importance of Reaction Mechanism Involved in Design of the Catalyst and the Reactor for Future Ammonia Synthesis
Presentation

Importance of Reaction Mechanism Involved in Design of the Catalyst and the Reactor for Future Ammonia Synthesis

Ken-ichi Aika

The ammonia synthesis reaction is considered to involve several elementary steps [1]: N2 + 2＊ → 2N(a) (1) H2 + 2＊ → 2H(a) (2) N(a) + H(a) → NH(a) + ＊ (3) NH(a) + H(a) → NH2 (a) + ＊ (4) NH2 (a) + H(a) → NH3(a) + ＊ (5) NH3(a) → NH3 + ＊ (6) Here, the symbol ＊ indicates empty sites. For most metal catalysts, the dissociative adsorption of dinitrogen (step 1) is the rate-determining step, and all the other steps and its reverse step (from 2 to 6) are fast enough to be almost in equilibrium for…

Ammonia as an Energy Carrier for Renewable Energy
Presentation

Ammonia as an Energy Carrier for Renewable Energy

Ken-ichi Aika

At present, ammonia is mostly formed through reforming of natural gas (CH4). A 1,000 ton per day plant is said to consume about 35 GJ of natural gas to produce 1 ton of ammonia (22.5 GJ of enthalpy). About 50% of extra energy is wasted. If 1 ton ammonia is produced through water electrolysis, 22.5 GJ of electricity is necessary theoretically. Here again, extra electric energy must be wasted. The author discusses roughly how the efficiency depends upon the process size and the renewable energy cost.