Ammonia synthesis by N_2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe_2O_3

摘要

The Haber-Bosch process to produce ammonia for fertilizer currently relies on carbon-intensive steam reforming of methane as a hydrogen source. We present an electrochemical pathway in which ammonia is produced by electrolysis of air and steam in a molten hydroxide suspension of nano-Fe_2O-3. At 200℃ in an electrolyte with a molar ratio of 0.5 NaOH/0.5 KOH, ammonia is produced at 1.2 volts (V) under 2 milliamperes per centimeter squared (mA cm~(-2)) of applied current at coulombic efficiency of 35% (35% of the applied current results in the six-electron conversion of N_2 and water to ammonia, and excess H_2 is cogenerated with the ammonia). At 250℃ and 25 bar of steam pressure, the electrolysis voltage necessary for 2 mA cm~(-2) current density decreased to 1.0 V.