Operando-FTIR investigation of bifunctional Pt or Pd,Fe-HMOR catalyst for simultaneous abatement of NOx and N2O by CH4

The simultaneous removal of NOx and N2O is performed by a bifunctional catalyst in which Pt or Pd metal particles located outside MOR channels abate NOx and Fen+ ions located at exchanging sites inside the MOR channels abate N2O. The reductants/oxidants ratio in the reactant mixture, CH4/(NO+N2O+O2), affects the oxygen transfer processes at the active sites, determining their redox states. The formation of adsorbed NOy species that can deactivate the catalyst occurs on oxidized sites. The formation of adsorbed NH4+ species probes the Pt or Pd metal nanoparticles formation. The different interaction strength of cations with MOR exchanging sites, weak for Pt and Pd ions and strong for Fe ones, leads to active sites in different locations, aggregated noble-metal nanoparticles on external surface and Fe ions confined inside the channels, guaranteeing simultaneous and nearly independent pathways for the two abatements.