【摘要】 低温Fe基费托催化剂的主要活性相是_η-Fe₂C,CO在该催化剂上的吸附与活化行为是Fe基费托合成反应的重要步骤。为了从原子尺度上研究这一过程,本文基于密度泛函理论计算,在η-Fe₂C（011）完美表面和缺陷表面上对CO的吸附和活化行为进行了系统的对比研究。计算结果表明,CO在完美表面上的最稳定吸附位为与表面Fe结合的Top位,但活化前驱体位于三齿空位。CO直接解离路径因为能垒太高在_η-Fe₂C（011）完美表面上很难发生,而以HCO为中间体的H辅助CO解离路径则更有优势。当_η-Fe₂C（011）表面产生C空缺时,其生成的四齿空位成为CO的最稳定吸附位和活性位。同时,CO的直接解离能垒大幅下降,这导致CO直接解离和以HCO为中间体的H辅助解离路径可能同时发生。更多还原

【Abstract】 Fe₂C is discriminated as the active phase of the low-temperature Fischer-Tropsch synthesis（FTS）.CO adsorption and activation on this catalyst is the key step during the Fe-based FTS.In order to gain insight to this process,spin-polarized density functional theory calculations were performed to investigate the CO adsorption and activation on both the perfect and defectiveη-Fe₂C（011）surfaces.The calculated results show that the most stable configuration of CO adsorption is the top site binding with Fe atom,while the precursor state for CO dissociation is the3Fsite.The direct CO dissociation can hardly occur due to the high CO dissociation barrier,and the H-assisted CO dissociation via HCO intermediate is proposed to be as the dominant activation pathway.Furthermore,with the formation of C-vacant site,the 4Fsite works as the most stable adsorption and activation site,with largely decreases of direct CO dissociation barriers,leading to the similar overall CO activation energy barriers for both direct and H-assisted CO dissociation via formation of HCO.Therefore,they may occur simultaneously with the C-vacant site over theη-Fe₂C（011）surface.更多还原