Clean Conversion of Aqueous Ammonia Using a Solid Oxide Cell

Abstract

Waste aqueous ammonia is produced in significant quantities as part of coke production processes required for steelmaking. In this work, the utilization of a simulated aqueous ammonia waste (ammonium hydroxide) was investigated using a commercially available anode-supported solid oxide cell. The electrical performance of the cell was characterized using I-V curves and the output gases from the anode were measured in real-time using quadrupole mass spectrometry. Upon delivery to the anode, there was total decomposition of ammonia to form hydrogen and nitrogen with no NO x formation observed. The cell operated more efficiently in fuel cell mode due to alleviation of OCV, activation, and concentration losses. In electrolysis mode, the cell produced H 2 through a mixture of catalytic ammonia decomposition (48 vol%) and electrochemical H 2 O reduction (52 vol%) to yield output gas mixtures composed of 90-93 vol% H 2 (voltage dependent) balanced only in N 2 .