γ‑Fe2O3‑M41S Sorbents for H2S Removal: Effect of Different Porous Structures and Silica Wall Thickness

In this work, the effect of the M41S support pore structure (hexagonal or cubic) and of the wall thickness of the silica mesochannels has been evaluated aimed at achieving more and more efficient and regenerable iron oxide-based sorbents for H2S removal at midtemperature. With this purpose, we set up a simple Pluronic-free synthetic strategy capable of producing silica supports with hexagonal (MCM- 41) or cubic (MCM-48) pore structure with different wall thicknesses that have been used to fabricate the corresponding sorbents made up of iron oxide nanoparticles homogeneously dispersed into the mesochannels. The combined use of 57Fe-Mössbauer Spectroscopy and DC magnetometry has allowed for ascertaining the presence of maghemite in the form of ultrasmall nanoparticles in both composites and gives new insights on the influence of the different silica matrices on the active phase features. The performances of the sorbents have been evaluated at mid temperature (300 °C) through three repeated sulfidation and regeneration cycles and then correlated to their microstructure and textural properties.