Further discussion on the mechanism of hydrogen transfer in direct coal liquefaction
Further discussion on the mechanism of hydrogen transfer in direct coal liquefaction
复制标题
煤直接液化氢转移机理的进一步探讨
DOI：
10.1016/j.cattod.2020.10.009
复制
发表时间：
2021
期刊：
影响因子：
5.3
通讯作者：
Li Wen-Ying
中科院分区：
文献类型：
--
作者：
Wang Xing-Bao;Fan Huan-Huan;Xie Zi-Zheng;Li Wen-Ying
煤直接液化（DCL）中使用的供氢溶剂（H-donor）对于石油产量和产品分布起着至关重要的作用。然而，DCL中氢供体与煤之间的反应机制尚不清楚。在这项研究中，使用模型化合物四氢化萘（氢供体）和二苯甲烷（DPM，煤）研究了 DCL 中氢供体和煤的反应。采用密度泛函理论计算来检查热解自由基和溶剂介导的氢解机制。基于计算结果，提出了一种改进的溶剂介导氢解机制，即协同双氢转移机制，其中β-和α-氢原子同时从四氢化萘转移到DPM的正碳和间碳原子。计算出的氢转移能垒低于大多数煤的键解离焓。协同双氢转移反应的能垒范围与Cary−C烷基键的解离焓无关，尽管它们与不同溶剂的供氢能力顺序一致。本研究可为提高DCL中H供体的效率提供理论指导。
The hydrogen-donor solvent (H-donor) used in direct coal liquefaction (DCL) plays a critical role in both the oil yield and distribution of the products. However, the mechanism of the reaction between H-donor and coal in the DCL is unclear. In this study, the reaction of H-donor and coal in the DCL was investigated using the model compounds tetralin (H-donor) and diphenylmethane (DPM, coal). Density functional theory calculations were employed to examine both pyrolytic radical and solvent-mediated hydrogenolysis mechanisms. Based on the computed results, a modified solvent-mediated hydrogenolysis mechanism was proposed, namely the synergistic double-hydrogen-transfer mechanism, in which theβ- andα-hydrogen atoms simultaneously transfer from tetralin to theipso- andmeta-carbon atoms of DPM. The calculated energy barriers of hydrogen transfer were lower than most of the bond dissociation enthalpies for coal. The energy barriers range of the synergistic double-hydrogen-transfer reaction did not correlate with the dissociation enthalpies of Caryl−Calkylbond, although they were consistent with the order of the hydrogen-donating abilities of different solvents. This study may provide a theoretical guidance to improve the efficiency of H-donor in the DCL.