Improving the energy yield of plasma-based ammonia synthesis with in situ adsorption

Plasma-based ammonia synthesis is studied as an option for electrifying the chemical industry. However, the energy efficiency of plasma-based ammonia synthesis is severely limited by ammonia decomposition in the plasma phase. We show that the use of zeolite 4A as an adsorbent for in situ ammonia removal from the plasma phase suppresses product decomposition, thereby increasing the ammonia yield. It is found that the ammonia yield for plasma-chemical ammonia synthesis with in situ ammonia removal is improved by a factor of 2 compared to steady-state plasma-chemical ammonia synthesis. Plasma-induced surface heating limits the effective ammonia adsorption capacity of the zeolite, decreasing the adsorption capacity. In situ product removal is of interest for plasma chemistry and plasma catalysis, in general, as the product decomposition in the plasma is a general phenomenon limiting the product yield.