Abstract The chemical reaction between a graphite model edge and H2O is crucial in steam gasification. This study used density functional theory (DFT) calculations to systematically evaluate the reaction path of steam gasification. The research results indicate that a graphite model edge without active cites is more suitable for use as an initial model for steam gasification. The aromaticity of the graphite model edge and the desorption of CO are linearly related. H atoms from H2O are transferred to the graphite model edge, destroying the aromaticity of the edge carbon structure and facilitating the subsequent desorption process, which may be the cause of the higher reactivity of steam compared to CO2 gasification. From a thermodynamic perspective, hydrogen transfer may be the rate-determining step of the overall reaction. The results of this paper can explain the kinetic differences in previous experiments that used water with varying isotopes of H (H2O vs D2O) and graphite in the gasification reaction (Yates and McKee, 1981; Mims and Pabst, 1987; Fletcher and Thomas, 2007). Our results provide new insights into the H transfer mechanism in steam gasification.

中文翻译：

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蒸汽气化过程中H转移机理的DFT研究

摘要 石墨模型边缘与 H2O 之间的化学反应在蒸汽气化中至关重要。本研究使用密度泛函理论 (DFT) 计算来系统地评估蒸汽气化的反应路径。研究结果表明，没有活性位点的石墨模型边缘更适合作为蒸汽气化的初始模型。石墨模型边缘的芳香性与CO的解吸呈线性相关。来自 H2O 的 H 原子被转移到石墨模型边缘，破坏了边缘碳结构的芳香性并促进了随后的解吸过程，这可能是与 CO2 气化相比蒸汽具有更高反应性的原因。从热力学的角度来看，氢转移可能是整个反应的速率决定步骤。本文的结果可以解释之前在气化反应中使用具有不同 H2O 同位素的水和石墨的实验中的动力学差异（Yates 和 McKee，1981 年；Mims 和 Pabst，1987 年；Fletcher 和 Thomas，2007 年） ）。我们的研究结果为蒸汽气化中的 H 转移机制提供了新的见解。