(177e) Metal-Metal Oxide Interaction Induced Yolk-Shell Nanocrystals for Acetylene Semihydrogenation | AIChE

(177e) Metal-Metal Oxide Interaction Induced Yolk-Shell Nanocrystals for Acetylene Semihydrogenation


Zhu, H., Virginia Tech Chemical Engineering
Metal-metal oxide interactions play an important role in heterogeneous catalysis, and therefore, have spurred tremendous interest in the in-depth understanding and investigation of the strength, stability, and dynamic evolution of such interactions. Herein, we synthesize a series of core-shell metal-iron oxide nanocrystals (M-FeOx, M = Pd, Pt, Au) and employ both in situ and ex situ electron microscopy and X-ray absorption spectroscopy (XAS) to study the atomic and nanoscopic dynamic M-FeOx interactions under reductive atmosphere (H2) at elevated temperatures. The H2-treated M-FeOx core-shell structures all evolved into yolk-shell structures (denoted as M-FeOx-H). However, dissimilar metal-metal oxide interactions have been observed among the three M-FeOx-H systems. We show that Pd core interacts strongly with the FeOx shell after the H2 treatment, featured by the formation of Pd single atoms on the FeOx shell and increased Pd-Fe bonding. Meanwhile the Pt core transforms into an ordered PtFe intermetallic structure and Pt single atoms are anchored on the FeOx shell immediately upon the coating of FeOx. The PtFe intermetallic core is thermodynamically stable without bonding change during the post-synthesis H2 treatment. In contrast, Au-FeOx-H forms negligible Au-Fe bonding nor Au single atoms. Finally, we conduct comprehensive catalytic tests of M-FeOx-H systems on acetylene semihydrogenation reaction. Among the three systems, Pd-FeOx-H exhibits best catalytic performance, achieving 100% acetylene conversion and 86.5% ethylene selectivity at 60 °C. Our work not only depicts the dynamic evolution of the metal-metal oxide interactions of M-FeOx systems but also offers a unique method to synthesize yolk-shell nanocomposites consisting single atoms and intermetallic alloys. The resulting M-FeOx-H yolk-shell nanocrystals can be employed as excellent catalyst for reactions including but not limited to alkyne hydrogenation.