Fe2O3 supported on hollow micro/mesospheres silica for the catalytic partial oxidation of H2S to sulfur

Abstract

A family of Fe-based catalysts supported on hollow silica mesospheres have been synthesized and tested in the catalytic partial oxidation of H2S to elemental sulfur at 170-180ºC, atmospheric pressure and under 300 minutes of time-on-stream. The characterization of the synthesized catalysts by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis spectra (DRS), H2-termoprogrammed reduction (H2-TPR), N2 adsorptiondesorption at -196 ºC and X-ray photoelectron spectroscopy (XPS) reveals the formation of a catalytic system with high micro-and mesoporosity and high dispersion of the Fe2O3 species. The catalytic results reported a high activity in the partial oxidation of H2S, reaching over the HMS-10Fe (i.e. with 10 wt% of iron loading) catalyst at 180 ° C and after 300 minutes of time in the stream (TOS), a higher conversion value close to 94% with a selectivity towards elemental sulfur of 98%. The comparison of HMS-10Fe catalysts with other SiO2-based supports, as a fumed silica (Cab-osil; Cab) or a mesoporous silica (SBA-15), indicates changes in the catalytic activity for H2S conversion depending on support, and showing the following trend: HMS-10Fe > SBA-10Fe > Cab-10Fe. These results suggest that the use of a support with a narrow pore tend to achieve facilitate the iron dispersion favoring higher conversion rates.

H2S Oxidative Decomposition Reaction in the Presence of CH4 over Metal-Sulfide-Based Catalysts: A Preliminary Investigation

“…In this novel process, a suitable amount of oxygen is added to the reaction system in order to use the heat produced by the H 2 S oxidation (H 2 S + 1 / 2 O 2 → 1 / 2 S 2 + H 2 O) to balance the endothermicity of the H 2 S decomposition reaction (H 2 S ↔ H 2 + 1 / n S n ), thus obtaining at the same time sulfur, H 2 O, and H 2 . − Because of the presence of oxygen in the reaction system, it is probable to observe SO 2 formation among the reaction products, which is highly favored kinetically over a wide range of temperature . The role of the catalyst is needed to improve the selectivity to hydrogen and sulfur, depressing as much as possible SO 2 formation while ensuring high H 2 S conversion. − …”