Oxidation of Ammonia in Aqueous Solution to Nitrogen for Ammonia Removal

摘要

Catalysts are formulated to resemble a direct ammonia/air fuel cell at short circuit at the nanoscale level to convert ammonia in aqueous solution directly and spontaneously to nitrogen at near or above ambient temperature. The catalyst particle contains a type-A catalyst subparticles for ammonia oxidation to nitrogen, and a type-C catalyst subparticles for oxygen reduction, with the type-A and type-C catalyst subparticles electrically shorted. Advantages realized at the nanoscale level are enhanced conductances for electrons and hydroxyl anions between the neighboring type-A and type-C catalyst subparticles. With the catalysts packed and confined in a catalyst bed in a chemical reactor, the direct conversion of ammonia in an aqueous phase to nitrogen can be carried out continuously for ammonia removal from a water stream in a compact package, and without the high cost arising from constructing and maintaining a bulk electrochemical device, and without the step of exacting the ammonia into gas phase.