Sulfur dioxide (SO₂) and carbon dioxide (CO₂) removals are of great significance for fossil fuel combustion, where they can be simultaneously captured by calcium‐based absorbents. Nevertheless, the CO₂ uptake capacity declines with SO₂ partial pressures. This paper aims at explaining the mechanisms of steam‐declined sulfation and steam‐enhanced carbonation by density functional theory calculations. CaO(001) surface is chosen as the absorbent, and the transition state is calculated to obtain the desorption barrier energy of the adsorbates. By analyzing the desorption of the adsorbate on pristine CaO(001) surface and the CaO(001) surface that has adsorbed other adsorbate, it can be concluded that SO₂ adsorption inhibits CO₂ adsorption since the barrier energy of CO₂ desorption on SO₂‐CaO(001) surface (24.15 kJ mol^–1) is less than CO₂ desorption on CaO(001) surface (129.52 kJ mol^–1). By comparing the coadsorption energy of the two adsorbates with the sum of the adsorption energy of each adsorbate, it is practical that the H₂O adsorption inhibits SO₂ adsorption because the calculated coadsorption energy (−221.27 kJ mol^–1) is larger than the sum of H₂O adsorption energy (–100.00 kJ mol^–1) and SO₂ adsorption energy (−194.37 kJ mol^–1). However, the calculated coadsorption energy of H₂O and CO₂ adsorption (−254.89 kJ mol^–1) is less than the sum of CO₂ adsorption energy (−144.23 kJ mol^–1) and H₂O adsorption energy (−100.00 kJ mol^–1), indicating the promotion of CO₂ adsorption. Steam in the adsorption process plays the roles of sulfation suppression and carbonation enhancement. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

中文翻译：

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通过DFT计算得出蒸汽下降的硫酸化和蒸汽增强的碳酸化的机理

二氧化硫（SO ₂）和二氧化碳（CO ₂）的去除对于化石燃料燃烧具有重要意义，在燃烧过程中，钙基吸收剂可以同时捕获它们。然而，CO ₂吸收能力随SO ₂分压而下降。本文旨在通过密度泛函理论计算来解释蒸汽下降的硫酸化和蒸汽增强的碳酸化的机理。选择CaO（001）表面作为吸收剂，并计算过渡态以获得被吸附物的解吸势垒能。通过分析原始CaO（001）表面和已吸附其他吸附质的CaO（001）表面吸附质的解吸，可以得出SO _2的结论。吸附抑制了CO _2的吸附，因为在SO ₂ ‐CaO（001）表面（24.15 kJ mol ^–1）脱附的CO ₂的势垒小于在CaO（001）表面（129.52 kJ mol ^–1）脱附的CO ₂。通过将两种被吸附物的共吸附能与每种被吸附物的吸附能之和进行比较，H ₂ O吸附会抑制SO ₂吸附是可行的，因为计算出的共吸附能（-221.27 kJ mol ^–1）大于H ₂ O吸附能（–100.00 kJ mol ^–1）和SO _2的总和吸附能（−194.37 kJ mol ^–1）。但是，H ₂ O和CO ₂吸附的共吸附能（−254.89 kJ mol ^–1）小于CO ₂吸附能（−144.23 kJ mol ^–1）和H ₂ O吸附能（−100.00 kJ）的总和mol ^–1），表明促进了CO ₂吸附。蒸汽在吸附过程中起着硫酸盐抑制和碳酸化作用的作用。©2019年化学工业协会和John Wiley＆Sons，Ltd.