Mechanism of Mercury Removal in Syngas by Co-modified Activated Coke with H2S

doi:10.11944/j.issn.1000-0518.2018.12.180016

Chinese Journal of Applied Chemistry ›› 2018, Vol. 35 ›› Issue (12): 1497-1506.DOI: 10.11944/j.issn.1000-0518.2018.12.180016

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Mechanism of Mercury Removal in Syngas by Co-modified Activated Coke with H₂S

MAO Juezhen,ZHOU Jinsong(),LI Xueqian,ZHOU Qixin,CAO Hui

State Key Laboratory of Clean Energy Utilization,Zhejiang University,Hangzhou 310027,China

Received:2018-01-18 Accepted:2018-03-12 Published:2018-12-05 Online:2018-12-10
Contact: ZHOU Jinsong
Supported by:
Supported by the National Natural Science Foundation of China(No.51576173)

Abstract

Abstract:

Activated coke modified with cobalt(Co-AC) were prepared through impregnation and high temperature calcination method, and then characterized by BET(Brunauer-Emmett-Teller), XRD(X-ray diffraction) analysis. The adsorption of gas-phase elemental mercury by Co-AC under nitrogen and simulated syngas(N₂, H₂, CO, H₂S) was studied on a bench-scale fixed-bed apparatus and focus on the influence of H₂S. The results show that 5%Co-AC exhibits excellent Hg⁰ removal capacity at 120 ℃ and 97.8% of Hg⁰ can be removed in the presence of H₂S. In addition, based on the density functional theory, the adsorption energy and bond length of H₂S, HS and S on Co₃O₄ (110) surface were calculated. Firstly, H₂S will dissociate into HS and S in turn by comparing the bond length of H—S. Secondly the adsorption characteristic of Hg was calculated on S-Co₃O₄(110 ). The results indicate that Hg reacts with S to form a stable HgS with an adsorption energy of -3.503 eV and the adsorption of Hg follows Eley-Rideal mechanism.With an elevated temperature, mercury removal is suppressed, because the amount of active sulfurs on the surface decreases and the interaction between Hg and S is weakened. The reaction mechanism of Hg⁰ removal on the surface of cobalt-based adsorbents in the presence of H₂S was proved. This provides a theoretical guidance for synergistic removal of H₂S and Hg⁰ in coal gas.

Key words: cobalt modification, activated coke, removal efficiency, denstiy functional theory, H₂S

MAO Juezhen, ZHOU Jinsong, LI Xueqian, ZHOU Qixin, CAO Hui. Mechanism of Mercury Removal in Syngas by Co-modified Activated Coke with H₂S[J]. Chinese Journal of Applied Chemistry, 2018, 35(12): 1497-1506.

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Mechanism of Mercury Removal in Syngas by Co-modified Activated Coke with H₂S

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