Electrochemical Synthesis of Ammonia in Alkaline Media
The electrochemical synthesis of ammonia has been proposed to reduce the energy used in the generation of NH3. By using electricity as the driving force, ammonia can be generated at room temperature (25 oC) and atmospheric pressure (1 atm).
At the cathode side of an electrochemical cell, nitrogen (N2) gas is bubbled over the cathode. With the help of the cathode catalyst, N2 will be reduced to NH3 and hydroxyl ion (OH–) in the presence of water (Equation 1):
6e- + N2 + 6H2O → 2NH3 + 6OH- Eocathode = -0.77V/SHE 
At the anode side, hydrogen gas (H2) is bubbled and the H2 will be oxidized over the anode catalyst in the presence of OH– ions to form water (Equation 2):
3H2 + 6OH- → 6H2O + 6e- Eoanode = -0.83V/SHE 
The overall reaction for this electrochemical cell (galvanic cell), where N2 and H2 is supplied to cathode and anode respectively, is shown in Equation 3:
N2 + 3H2 → 2NH3 
The thermodynamic cell voltage for the synthesis of ammonia in this galvanic cell is 0.06 V.
The above listed chemical reactions are related to the, well proven, electrolysis of ammonia process (5). During the electrolysis of ammonia, electric current is applied to oxidize NH3 to N2 at the anode and water is reduced to H2 and OH– ions at the cathode. Reversing these reactions in a galvanic cell should produce ammonia from N2 and H2 gases. The focus of the present investigation is to synthesize, electrochemically, ammonia from N2 and H2 gases in 1 M KOH solution.
The effect of gas (N2 and H2) flow rates, concentration of KOH solution, amount of current drawn from the galvanic cell, and type of membrane used will be studied for the electrochemical synthesis of ammonia. The percentage of ammonia yield and current efficiencies for different operating conditions will be determined and analyzed.
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