选择性
化学
钴
催化作用
硫黄
离解(化学)
费托法
吸附
无机化学
乙炔
密度泛函理论
光化学
有机化学
计算化学
作者
Yagmur Daga,Ali Can Kızılkaya
出处
期刊:Catalysts
[MDPI AG]
日期:2022-04-10
卷期号:12 (4): 425-425
被引量:8
标识
DOI:10.3390/catal12040425
摘要
Sulfur is a common poison for cobalt-catalyzed Fischer–Tropsch Synthesis (FTS). Although its effects on catalytic activity are well documented, its effects on selectivity are controversial. Here, we investigated the effects of sulfur-covered cobalt surfaces on the selectivity of FTS using density functional theory (DFT) calculations. Our results indicated that sulfur on the surface of Co(111) resulted in a significant decrease in the adsorption energies of CO, HCO and acetylene, while the binding of H and CH species were not significantly affected. These findings indicate that sulfur increased the surface H/CO coverage ratio while inhibiting the adsorption of carbon chains. The elementary reactions of H-assisted CO dissociation, carbon and oxygen hydrogenation and CH coupling were also investigated on both clean and sulfur-covered Co(111). The results indicated that sulfur decreased the activation barriers for carbon and oxygen hydrogenation, while increasing the barriers for CO dissociation and CH coupling. Combining the results on elementary reactions with the modification of adsorption energies, we concluded that the intrinsic effect of sulfur on the selectivity of cobalt-catalyzed FTS is to increase the selectivity to methane and saturated short-chain hydrocarbons, while decreasing the selectivity to olefins and long-chain hydrocarbons.
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