Alumina-supported manganese oxide sorbent prepared by sub-critical water impregnation for hot coal gas desulfurization
2013
Wang, Jiancheng | Liu, Lianwei | Han, Lina | Hu, Yongfeng | Chang, Liping | Bao, Weiren
Manganese oxide was loaded on the surface of γ-Al₂O₃ by sub-critical water impregnation using manganese acetate and manganese nitrate precursors to synthesize Mn(A) and Mn(N) sorbents for removing H₂S from hot coal gas. Active component precursors present very obvious effect on the desulfurization capacity of sorbent. Mn(A, 11) sorbent with 11% Mn content in γ-Al₂O₃ maintains a desulfurization efficiency of close to 100% over 480min. However, it reduces to below 90% for Mn(N, 11) sorbent when the reaction lasts over 75min. The characterizing results of fresh and used sorbents from different precursors using AAS, SEM, BET, Raman, XAS and XPS techniques show that the acidity and alkalinity of active component precursor solution greatly influences the loading rate, valence state and dispersion of manganese on γ-Al₂O₃, which are the main properties for improving desulfurization performance of sorbents. The manganese loading rate of Mn(A) sorbent is much higher than Mn(N) sorbent. The better dispersion of manganese on γ-Al₂O₃ and the higher Mn²⁺ and Mn³⁺ contents on the surface of sorbent afford the high desulfurization activity of Mn(A). Moreover, Mn(A, 11) performs well in removing H₂S from hot gas at 400°C after three desulfurization -regeneration cycles.
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