Effect of H₂S/HCl on the removal of elemental mercury in syngas over CeO₂-TiO₂

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• 作者：Wenhui Hou ; Jinsong Zhou ; Pan Qi ; Xiang Gao ; Zhongyang Luo
• 关键词：Mercury ; Hydrogen sulfide ; Syngas ; Removal ; CeO2&ndash ; TiO2
• 刊名：Chemical Engineering Journal
• 出版年：1 April, 2014
• 年：2014
• 卷：241
• 期：Complete
• 页码：131-137
• 全文大小：1846 K

文摘

CeTi sorbent (CeO₂ supported on TiO₂) was employed to remove elemental mercury (Hg⁰) from syngas when H₂S and/or HCl are present. CeTi sorbents exhibited higher Hg⁰ removal efficiency compared with S-impregnated activated carbon. H₂S and HCl were the most effective syngas components responsible for Hg⁰ removal when they were employed separately. When 400 ppm H₂S and 10 ppm HCl were introduced separately with a balance of dry N₂, over 97% of the Hg⁰ was removed under the experimental conditions. However, the combination of H₂S and HCl exerted a prohibitive effect on Hg⁰ removal, which could be attributed to two causes: (1) the HCl consumed the surface oxygen active for Hg⁰ removal, hence limiting Hg⁰ removal by H₂S; and (2) the H₂S competed with Hg⁰ for active adsorption sites, limiting the Hg⁰ removal by HCl. On the basis of the temperature-programmed decomposition (TPD) analysis and X-ray photoelectron spectroscopy (XPS) characterization of the sorbents, a Hg⁰ removal mechanism in the presence of H₂S over CeTi sorbents was proposed, suggesting that surface oxygen on the of CeTi sorbent supported the transformation of H₂S to active surface sulfur, through which Hg⁰ could be captured resulting in the formation of HgS.