This study investigates the influence of mesoporosity, pre-created by alkali etching in
ZSM-5 zeolite, on the characteristics of Fe3+ ion-exchange and subsequent changes in its
textural and optical properties. It is shown that the formed hierarchical porosity facilitates
the penetration of hydrated iron complexes into the internal channels. This not only
increases the degree of exchange, but also leads to the formation of multinuclear FexOy
clusters and, possibly, to the partial isomorphic replacement of Al3+ with Fe3+ in the framework.
Comprehensive characterization of mesoporous samples (XRD, SEM, N2 adsorption,
UV-Vis) confirms the preservation of the microporous crystal structure of MFI on the one
hand, and demonstrates a significant change in the distribution of iron-containing species
in mesoporous matrices on the other. The introduction of Fe ions significantly reduces
the bandgap energy, shifting the absorption edge into the visible range. The results obtained
demonstrate that preliminary mesostructuring is an effective approach for creating
hierarchically porous Fe zeolites with great potential for photocatalytic applications.