Fe-oxide/Al2O3 for the enhanced activity of H2S decomposition under realistic conditions: Mechanistic studies by in-situ DRIFTS and XPS

Fe-oxide nanoparticles (less than 2 nm) were evenly dispersed onto mesoporous Al2O3 beads, and the structure was used as an adsorbent and catalyst for removing H2S. The Fe-oxide enhanced the removal efficiency of H2S molecules at room temperature and suppressed SO2 emission into the gas phase upon thermal treatment of the H2S-covered substrate. Compelling evidence is provided by in-situ DRIFTS and XPS that Fe-oxide not only catalyzes the conversion of H2S to S8, as previously suggested, but also facilitates the formation of SO42− species on the surface of Fe-oxide/Al2O3. A spill-over process of SO42− from Fe-oxide to Al2O3 at their interfacial site was proposed. The removal efficiency of the SO42−-poisoned surfaces could be recovered by water cleaning. This study clearly provides molecular level information about the problems one can face when supported Fe-oxide catalysts are used as H2S-removing agents in field applications, and details regarding how one can avoid such problems.