Hexaaluiminate-type catalysts for n2o abatement

Identifier:  TDX:889

Handle: https://hdl.handle.net/20.500.11797/TDX889

Authors:  Santiago Redondo, Marta

Abstract:
Over the last decades, a large number of catalysts have been studied for catalytic decomposition of N2O. Most of these catalysts failed to be an alternative option for already commercialized counterparts and few of them showed reasonable activities under realistic conditions. Metal‐substituted hexaaluminates, so far applied mainly in the catalytic combustion of methane in gas‐turbine applications, show excellent qualities as promising candidates for high‐temperature N2O abatement. Their layered structure together with the presence of redox sites provides chemical stability, high‐resistance to thermal shock and high activity. This thesis focuses on the development of metal‐substituted hexaaluminates, a novel catalytic system for high‐temperature N2O abatement. Synthesis, in situ thermal activation and characterization of metal‐substituted hexaaluminates have been carried out with the aim of gaining a better understanding of their formation. The catalytic activity was also evaluated simulating realistic conditions in both processes, i.e. nitric acid plant and stationary combustion. Additionally, an alternative route of synthesis, using templating approaches for the first time, has been successfully developed improving their catalytic activity. Finally, transient studies in the Temporal Analysis of Products (TAP) reactor have been carried out in order to gain insights into the N2O decomposition mechanism into N2 and O2.