煤气气氛对汞在CeO_2(111)面吸附影响机理研究

Effect of Syngas Atmosphere on Adsorption of Elemental Mercury on CeO_2(111) Surface

CeO_2作为具有强大储氧能力的金属氧化物,在煤气条件下展现出极强的脱汞能力。然而对于不同煤气气分下Hg^0脱除的影响机制尚不明确。本文基于密度泛函理论的第一性原理,从竞争活性位的角度出发探究煤气气氛对Hg在CeO_2(111)面吸附的影响机制。结果表明,H2不会影响Hg在CeO_2(111)面的吸附;CO能够与部分活性S反应生成COS,消耗一部分活性S,抑制Hg在CeO_2(111)面的吸附;H_2O与Hg和H2S竞争吸附Ce Top位并且H_2O解离形成的H会抑制H_2S和HS的解离,减少活性S产生,抑制Hg的吸附。

As a metal oxide with powerful oxygen storage capacity, ceria has shown a strong ability to remove mercury in syngas. However, the mechanism of the removal of Hg-0 under different syngas atmospheres is not clear. From the perspective of competiting active absorption sites, the first principle of density functional theory was used to investigate the mechanism of syngas atmosphere＇s influence on the adsorption of Hg on CeO_2（111） surface. The results show that H2 does not affect the adsorption of Hg on the CeO_2（111）; CO reacts with the partially active S to form COS, and consumes a portion of the active S, thereby inhibiting the adsorption of Hg on CeO_2（111）; H_2 O competes active absorption sites（Ce Top site） with Hg and H2 S. And H_2 O dissociates to form H which can inhibit the dissociation of H_2 S and HS, and then reduce the production of active S, thereby inhibiting ceria from absorbing Hg.