Dasgupta Anish, He Haoran, Gong Rushi, Shang Shun-Li, Zimmerer Eric K, Meyer Randall J, Liu Zi-Kui, Janik Michael J, Rioux Robert M
Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA.
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA.
Nat Chem. 2022 May;14(5):523-529. doi: 10.1038/s41557-021-00855-3. Epub 2022 Feb 3.
Intermetallic compounds offer unique opportunities for atom-by-atom manipulation of catalytic ensembles through precise stoichiometric control. The (Pd, M, Zn) γ-brass phase enables the controlled synthesis of Pd-M-Pd catalytic sites (M = Zn, Pd, Cu, Ag and Au) isolated in an inert Zn matrix. These multi-atom heteronuclear active sites are catalytically distinct from Pd single atoms and fully coordinated Pd. Here we quantify the unexpectedly large effect that active-site composition (that is, identity of the M atom in Pd-M-Pd sites) has on ethylene selectivity during acetylene semihydrogenation. Subtle stoichiometric control demonstrates that Pd-Pd-Pd sites are active for ethylene hydrogenation, whereas Pd-Zn-Pd sites show no measurable ethylene-to-ethane conversion. Agreement between experimental and density-functional-theory-predicted activities and selectivities demonstrates precise control of Pd-M-Pd active-site composition. This work demonstrates that the diversity and well-defined structure of intermetallics can be used to design active sites assembled with atomic-level precision.
金属间化合物通过精确的化学计量控制，为逐个原子地操纵催化组合提供了独特的机会。(Pd, M, Zn)γ-黄铜相能够在惰性Zn基体中可控地合成孤立的Pd-M-Pd催化位点（M = Zn、Pd、Cu、Ag和Au）。这些多原子异核活性位点在催化方面与Pd单原子和完全配位的Pd不同。在此，我们量化了活性位点组成（即Pd-M-Pd位点中M原子的身份）对乙炔半加氢过程中乙烯选择性产生的意外巨大影响。微妙的化学计量控制表明，Pd-Pd-Pd位点对乙烯加氢具有活性，而Pd-Zn-Pd位点未显示出可测量的乙烯向乙烷的转化。实验与密度泛函理论预测的活性和选择性之间的一致性表明，对Pd-M-Pd活性位点组成实现了精确控制。这项工作表明，金属间化合物的多样性和明确的结构可用于设计具有原子级精度组装的活性位点。
