Integrated Ammonia Synthesis and Separation

Abstract

Ammonia is made by combining nitrogen and hydrogen at high pressure. In the conventional process on the left, these gases are partially reacted at about 400 °C, and ammonia is recovered by condensation at −20 °C. In an alternative shown in the center, the reactor is the same, but the more complete separation is conducted by absorption in metal chlorides at about 150–400 °C. In this work, both reaction and absorption are integrated to occur in the same vessel at 400 °C. Experiments are conducted by combining a conventional Fe-based catalyst with NiCl2 and MgCl2 sorbents in a semibatch reactor in the presence of stoichiometric nitrogen and hydrogen gases. This alternative has synthesis rates comparable with the other two but with a lower capital investment necessary for distributed ammonia synthesis using solar or wind energy.