沮丧的刘易斯对
异构化
化学
路易斯酸
催化作用
氢化物
密度泛函理论
乙炔
空位缺陷
立体化学
计算化学
光化学
结晶学
有机化学
金属
作者
Zheng-Qing Huang,Liping Liu,Suitao Qi,Sai Zhang,Yongquan Qu,Chun‐Ran Chang
标识
DOI:10.1021/acscatal.7b02732
摘要
The development of heterogeneous frustrated-Lewis-pair (FLP) catalysts from homogeneous FLP conception is of great promise in practical applications. While our recent discovery has shown that all-solid FLPs can be created on ceria via surface oxygen vacancy regulation (Zhang et al. Nat. Commun. 2017, 8, 15266), a sound understanding of the intrinsic property and reactivity of the solid FLPs is still expected. Here we present a comprehensive theoretical study on the FLPs (Ce···O) constructed on CeO2(110) and (100) surfaces by using density functional theory calculations. We find that the creation of surface oxygen vacancy can enhance both the acidity of FLP-acid site and the basicity of FLP-base site. The enhanced acidity and basicity of Lewis sites together with the elongated distance of Lewis pairs (Ce···O) contribute to the high activity of solid FLPs. The dissociative activation of H2 on FLPs experiences a heterolytic pathway (H2 → Hδ+ + Hδ−) with a low activation energy of 0.07 eV on CeO2(110) and 0.08 eV on CeO2(100). Unlike the phenomenon on stoichiometric CeO2 surfaces that the dissociated hydride (Hδ−) adsorbed at Ce sites is prone to transfer to more stable O sites, the hydride on FLPs can be stabilized at Ce sites and thus benefits the hydrogenation of acetylene via an easier pathway. The rate-determining barriers of acetylene hydrogenation on FLP-CeO2(110) and FLP-CeO2(100) are calculated to be 0.58 and 0.88 eV, respectively. These results could help to understand the nature of solid FLPs and pave the way for rational design of heterogeneous FLP catalysts.
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