Modelling ammonia and nitrous oxide decomposition reactions in solid oxide fuel cells for combined energy generation and treatment of flue gas streams

Abstract

Solid oxide fuel cells (SOFCs) offer a promising technology for clean and efficient power generation. In this study, an SOFC combining in-situ hydrogen generation from ammonia with nitrous oxide reduction to nitrogen was simulated and validated against experimental results for the first time. Ammonia decomposition generates the hydrogen needed for the electroreduction of nitrous oxide, with simultaneous generation of electrical power. Nickel was considered as the anode catalyst since it is highly active for ammonia decomposition. Perovskite catalyst LSCF - lanthanum strontium cobalt ferrite, was used as the cathode where N2O, a potent greenhouse gas, is efficiently decomposed into harmless molecular nitrogen and oxygen. The simulation study was performed on ANSYS Fluent, a CFD platform. The developed simulator was revealed to be a powerful tool to understand and optimize the operating conditions of the reactor, when applied to the treatment of the flue gas of a nitric acid plant. Under optimal conditions, the modelled reactor displays current densities >100 mAcm(-2) and power densities of ca. 11 mWcm(-2), where full conversion of N2O could be obtained by adjustments of the residence time. Besides nitric acid plants, these findings provide valuable insights for further industries with N2O emissions and those involved in the delivery and storage of ammonia, ultimately contributing to the advancement of SOFC as an effective integrated technology for combined electrical generation and flue gas stream treatment. Synopsis : The development of new SOFCs enables the valorisation of potent greenhouse gases such as N2O and sustainable power generation.