Study of Ni-YSZ anode under pure and diluted NH3 conditions towards NO production

• Nitrous oxide (N 2 O) tail gas abatement was studied using Direct Ammonia (NH 3 ) Solid Oxide Fuel Cell (SOFC). • A 10 % concentration of NH 3 as fuel has only a minor impact on power density while increasing fuel utilization. • NH 3 oxidizes via simultaneous direct and indirect pathways, with the indirect being dominant. • Fuel dilution is determining condition for direct NH 3 oxidation to nitric oxide. • Sr 2 Fe 1.5 Mo 0.5 O 6-δ converts approximately 10 % of feed N 2 O. Direct ammonia solid oxide fuel cells (DA-SOFCs) have been widely recognized as highly efficient energy conversion devices. Their application to the reduction and valorisation of nitrous oxide (N 2 O), a potent greenhouse gas, represents a promising strategy for mitigating global warming while simultaneously addressing energy demands. The present work extends this concept by investigating an Sr 2 Fe 1.5 Mo 0.5 O 6- δ ||CGO||YSZ||Ni-YSZ solid oxide fuel cell (SOFC), providing insight into the simultaneous electrochemical reduction of N 2 O at the cathode and the electrochemical oxidation of NH 3 at the anode. This approach aligns with the objective of achieving N 2 O abatement and valorisation through the production of NO at the anode, a valuable intermediate in the nitric acid synthesis process. In this study, the anodic reaction is examined for different fuel compositions, ranging from pure NH 3 to 6 % of NH 3 balanced in N 2 , at an intermediate operating temperature of 750 °C. The results indicate that fuel dilution had no significant impact on the overall electrical performance of the cell, as decreasing the ammonia concentration from pure NH 3 to 10 % NH 3 led to only a moderate reduction in power density, from 75 to 62 mW cm −2 . Notably, operation under diluted fuel conditions enabled the electrochemical oxidation of NH 3 to produce NO, which makes operation under diluted conditions attractive. Concurrently, nitrous oxide decomposition at the cathode was ca . 10 %, which, although modest, is a promising result considering the high thermal stability of the N 2 O molecule.