Chen Hao, Lian Zan, Zhao Xiao, Wan Jiawei, Pieters Priscilla F, Oliver-Meseguer Judit, Yang Ji, Pach Elzbieta, Carenco Sophie, Treps Laureline, Liakakos Nikos, Shan Yu, Altoe Virginia, Wong Ed, Zhuo Zengqing, Yang Feipeng, Su Ji, Guo Jinghua, Blum Monika, H Lapidus Saul, Hunt Adrian, Waluyo Iradwikanari, Ogasawara Hirohito, Zheng Haimei, Yang Peidong, Bell Alexis T, López Núria, Salmeron Miquel
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
Institute of Chemical Research of Catalonia (ICIQ-CERCA), Barcelona Institute of Science and Technology (BIST), Tarragona, Spain.
Nat Commun. 2024 Nov 27;15(1):10294. doi: 10.1038/s41467-024-54578-3.
Cobalt is an efficient catalyst for Fischer-Tropsch synthesis (FTS) of hydrocarbons from syngas (CO + H) with enhanced selectivity for long-chain hydrocarbons when promoted by Manganese. However, the molecular scale origin of the enhancement remains unclear. Here we present an experimental and theoretical study using model catalysts consisting of crystalline CoMnO nanoparticles and thin films, where Co and Mn are mixed at the sub-nm scale. Employing TEM and in-situ X-ray spectroscopies (XRD, APXPS, and XAS), we determine the catalyst's atomic structure, chemical state, reactive species, and their evolution under FTS conditions. We show the concentration of CH, the key intermediates, increases rapidly on CoMnO, while no increase occurs without Mn. DFT simulations reveal that basic O sites in CoMnO bind hydrogen atoms resulting from H dissociation on Co sites, making them less available to react with CH intermediates, thus hindering chain termination reactions, which promotes the formation of long-chain hydrocarbons.
钴是一种用于由合成气（CO + H）费托合成（FTS）制备碳氢化合物的高效催化剂，当由锰促进时，对长链碳氢化合物具有更高的选择性。然而，这种增强作用的分子尺度起源仍不清楚。在此，我们使用由结晶CoMnO纳米颗粒和薄膜组成的模型催化剂进行了一项实验和理论研究，其中Co和Mn在亚纳米尺度上混合。利用透射电子显微镜（TEM）和原位X射线光谱（XRD、常压X射线光电子能谱（APXPS）和X射线吸收光谱（XAS）），我们确定了催化剂的原子结构、化学状态、活性物种及其在FTS条件下的演变。我们表明，关键中间体CH的浓度在CoMnO上迅速增加，而没有Mn时则不会增加。密度泛函理论（DFT）模拟表明，CoMnO中的碱性O位点结合了Co位点上H解离产生的氢原子，使它们不易与CH中间体反应，从而阻碍了链终止反应，促进了长链碳氢化合物的形成。
