Hydrogen sulfide removal from hot coal gas by various mesoporous silica supported Mn₂O₃ sorbents

Graphical abstract: - Highlights: • Mn₂O₃/KIT-1 presented the best desulfurization performance at 600–850 °C. • High sulfur capacity of Mn₂O₃/KIT-1 correlated closely with 3-D channel of KIT-1. • Desulfurization character depended strongly on framework structure of sorbents. • High steam content suppressed greatly the occurrence of sulfidation reaction. - Abstract: A series of 50 wt% Mn₂O₃ sorbents was prepared using various mesoporous silica, MCM-41, HMS, and KIT-1 as support. The influence of textural parameters of mesoporous silica, especially type of channel on the desulfurization performance of Mn₂O₃ sorbents was investigated at 600–850 °C using hot coal gas containing 0.33 vol.% H₂S. The fresh and used sorbents were characterized by means of N₂-adsorption, x-ray diffraction (XRD), high resolution transmission microscopy (HRTEM) and H₂ temperature- programmed reduction (H₂-TPR) techniques. The results confirmed that the manganese oxide was dispersed highly in regular pore channel of the mesoporous supports due to high surface area. Compared with the Mn₂O₃/diatomite, all mesoporous silica supported Mn₂O₃ sorbents exhibited high breakthrough sulfur capacity and a sharp deactivation rate after the breakthrough point. Compared to Mn₂O₃/MCM-41 and Mn₂O₃/HMS sorbent, the Mn₂O₃/KIT-1 showed better desulfurization performance because of the 3D wormhole-like channel. The high sulfur capacity of the Mn₂O₃/KIT-1 sorbent was maintained during the eight consecutive desulfurization-regeneration cycles. The Mn₂O₃/KIT-1 still presented high desulfurization activity when hot coal gas contained low steam (<5%)