Synthesis of ammonia at atmospheric pressure with the use of solid state proton conductors

Ammonia was synthesized from nitrogen and hydrogen at atmospheric pressure in a solid state proton-conducting cell reactor. Two types of reactors were used, one double-chamber and one single-chamber cell. In the double-chamber cell, hydrogen flowed over the anode and was converted into protons that were transported through the solid electrolyte and reached the cathode (Pd) over which nitrogen was passing. At 570 degrees C, nearly 80% of the electrochemically supplied hydrogen was converted into ammonia. In the single-chamber cell, hydrogen and nitrogen were fed in together and the solid electrolyte cell was suspended in the gaseous stream. At 750 degrees C, a NEMCA effect was observed but the enhancement was not very strong (Lambda < 2). This novel process eliminates the thermodynamic requirements on the temperature and pressure of operation of conventional catalytic reactors. (C) 2000 Academic Press.