Amsler Jonas, Sarma Bidyut B, Agostini Giovanni, Prieto Gonzalo, Plessow Philipp N, Studt Felix
Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
J Am Chem Soc. 2020 Mar 18;142(11):5087-5096. doi: 10.1021/jacs.9b12171. Epub 2020 Mar 6.
The potential of oxide-supported rhodium single atom catalysts (SACs) for heterogeneous hydroformylation was investigated both theoretically and experimentally. Using high-level domain-based local-pair natural orbital coupled cluster singles doubles with perturbative triples contribution (DLPNO-CCSD(T)) calculations, both stability and catalytic activity were investigated for Rh single atoms on different oxide surfaces. Atomically dispersed, supported Rh catalysts were synthesized on MgO and CeO. While the CeO-supported rhodium catalyst is found to be highly active, this is not the case for MgO, most likely due to increased confinement, as determined by extended X-ray absorption fine structure spectroscopy (EXAFS), that diminishes the reactivity of Rh complexes on MgO. This agrees well with our computational investigation, where we find that rhodium carbonyl hydride complexes on flat oxide surfaces such as CeO(111) have catalytic activities comparable to those of molecular complexes. For a step edge on a MgO(301) surface, however, calculations show a significantly reduced catalytic activity. At the same time, calculations predict that stronger adsorption at the higher coordinated adsorption site leads to a more stable catalyst. Keeping the balance between stability and activity appears to be the main challenge for oxide supported Rh hydroformylation catalysts. In addition to the chemical bonding between rhodium complex and support, the confinement experienced by the active site plays an important role for the catalytic activity.
从理论和实验两方面研究了氧化物负载的铑单原子催化剂（SACs）用于多相氢甲酰化反应的潜力。使用基于高级域的局部对自然轨道耦合簇单双激发并包含微扰三激发贡献（DLPNO-CCSD(T)）的计算方法，研究了铑单原子在不同氧化物表面的稳定性和催化活性。在氧化镁（MgO）和氧化铈（CeO）上合成了原子分散的负载型铑催化剂。虽然发现CeO负载的铑催化剂具有高活性，但MgO负载的铑催化剂并非如此，这很可能是由于扩展X射线吸收精细结构光谱（EXAFS）测定的受限效应增强，降低了MgO上铑配合物的反应活性。这与我们的计算研究结果非常吻合，我们发现平坦氧化物表面（如CeO(111)）上的铑羰基氢化物配合物具有与分子配合物相当的催化活性。然而，对于MgO(301)表面的台阶边缘，计算结果表明催化活性显著降低。同时，计算预测在高配位吸附位点上更强的吸附会导致催化剂更稳定。保持稳定性和活性之间的平衡似乎是氧化物负载的铑氢甲酰化催化剂面临的主要挑战。除了铑配合物与载体之间的化学键合外，活性位点所经历的受限效应对于催化活性也起着重要作用。
