Plasma Pretreatment of Pt Single-Atom Precursors Supported on Mechanically Activated Al 2 O 3 : Enhanced Performance in Propane Dehydrogenation

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Abstract
We investigated the effect of catalyst pretreatment with "cold" plasmas on the catalytic performance of Pt single-atom catalyst (SAC) precursors supported on Al2O3 for the propane dehydrogenation reaction. We found that the catalysts treated with a hydrogen plasma before the conventional calcination/reduction steps showed considerably increased propane conversion without loss of selectivity, whereas exposure to an argon plasma did not result in such an effect. Moreover, the H2 plasma-treated catalyst showed a lower deactivation rate, suggesting better long-term stability. The structural and chemical evolution of the catalysts studied by TEM, XAS, XPS, and DRIFTS showed that the H2 plasma: (i) partially reduces singly dispersed Pt2+ species and promotes Pt clustering; (ii) decreases the amount of Cl remaining after the use of the hexachloroplatinic acid precursor; and (iii) enhances surface defects in the alumina support. We propose that the promotional effect of the H2 plasma lies in the specific modification of the alumina surface, which in turn alters the metal-support interaction and leads to the formation of a more active Pt/Al2O3 interface during the subsequent oxidation and reduction steps. The results show that nonthermal plasma treatments of single-atom precursors can become a tool for tuning the catalytic performance of highly dispersed metal catalysts.
Funding Information
  • Bundesministerium f?r Bildung und Forschung (03EW0015B)
  • Deutsche Forschungsgemeinschaft (327886311 SFB 1316)
  • Alexander von Humboldt-Stiftung
  • FUNCAT

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