| Summary: | Layered 2D zeolite MCM-22 and its delaminated derivative, ITQ-2, were modified with iron, by different methods (ion-exchange and direct synthesis), and with the use of different precursors (FeSO<sub>4</sub>∙7H<sub>2</sub>O, Fe(NO<sub>3</sub>)<sub>3</sub>∙9H<sub>2</sub>O, and [Fe<sub>3</sub>(OCOCH<sub>3</sub>)<sub>7</sub>∙OH∙2H<sub>2</sub>O]NO<sub>3</sub> oligocations. The applied modifications were aimed at optimization of iron form in the samples (aggregation, amount, location, and reducibility), in order to achieve the highest catalytic activity in the N<sub>2</sub>O decomposition. The synthesis of the samples was verified with the use of XRD (X-Ray Diffraction), N<sub>2</sub>-sorption and ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy) techniques, while the form of iron in the samples was investigated by UV–vis-DRS (UV–vis diffuse reflectance spectroscopy), H<sub>2</sub>-TPR (Hydrogen Temperature-Programmed Reduction) and HRTEM (High-Resolution Transmission Electron Microscopy). The highest activity in the N<sub>2</sub>O decomposition presented the sample Fe(O,IE)MCM-22, prepared by ion-exchange of MCM-22 with Fe3(III) oligocations. This activity was related to the oligomeric Fe<sub>x</sub>O<sub>y</sub> species (the main form of iron in the sample) and the higher loading of active species (in comparison to the modification with FeSO<sub>4</sub>∙7H<sub>2</sub>O).
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