Palladium single-atom catalysts prepared via strong metal-support interaction for selective 1,3-butadiene hydrogenation

Selective hydrogenation of 1,3-budiatene to butenes is an effective way to eliminate the minor 1,3-budiatene impurities, which can cause intractable issues of catalyst deactivation in the C₄ olefins upgrading processes. To this end, Pd single atom catalysts (SACs) exhibit remarkable selectivity to desired butene products due to the adsorption configuration of 1,3-budiatene in a mono-π mode. However, it is still a grand challenge to prepare thermal stable Pd SACs with conventional synthetic methods. Herein, we acquired Pd SACs via the selective encapsulation strategy exploiting classical strong metal-support interaction (SMSI), during which Pd nanoparticles are more prone to be encapsulated by oxide overlayer than Pd single atoms, thus Pd single atoms exclusively staying exposed to the catalytic environment. Various characterizations, such as aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, electron energy loss spectroscopy, together with CO adsorbed in-situ diffuse reflectance infrared Fourier transform spectra have collectively demonstrated the successful synthesis of Pd SACs on CeO₂ support when we adjusted the reductive temperature to 600 ℃ (Pd/CeO₂-H600). The as-obtained Pd/CeO₂-H600 gives excellent catalytic performances in the selective hydrogenation of 1,3-budiatene with conversion of almost 100% and butenes selectivity of above 98% at 100 ℃. Moreover, the conversion of 99% and butenes selectivity of 97.5% can also remain nearly unchanged for 60 h at a weight hourly space velocity of 60,000 mL/g_cat/h. This work illustrates the effectiveness of this selective encapsulation strategy to construct Pd SACs and can probably provide a prospective avenue to prepare various SACs for selective hydrogenation processes.