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Reversible Intrapore Redox Cycling of Platinum in Platinum-Ion-Exchanged HZSM‑5 Catalysts

Authors
  • Yalcin, Kaan
  • Kumar, Ram
  • Zuidema, Erik
  • Kulkarni, Ambarish R
  • Ciston, Jim
  • Bustillo, Karen C
  • Ercius, Peter
  • Katz, Alexander
  • Gates, Bruce C
  • Kronawitter, Coleman X
  • Runnebaum, Ron C
Publication Date
Apr 05, 2024
Source
eScholarship - University of California
Keywords
License
Unknown
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Abstract

Isolated platinum(II) ions anchored at acid sites in the pores of zeolite HZSM-5, initially introduced by aqueous ion exchange, were reduced to form platinum nanoparticles that are stably dispersed with a narrow size distribution (1.3 ± 0.4 nm in average diameter). The nanoparticles were confined in reservoirs within the porous zeolite particles, as shown by electron beam tomography and the shape-selective catalysis of alkene hydrogenation. When the nanoparticles were oxidatively fragmented in dry air at elevated temperature, platinum returned to its initial in-pore atomically dispersed state with a charge of +2, as shown previously by X-ray absorption spectroscopy. The results determine the conditions under which platinum is retained within the pores of HZSM-5 particles during redox cycles that are characteristic of the reductive conditions of catalyst operation and the oxidative conditions of catalyst regeneration.

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