Dynamic Copper Site Redispersion through Atom Trapping in Zeolite Defects

Stephen Purdy, Gregory Collinge, Junyan Zhang, Shivangi Borate, Kinga Unocic, Qiyuan Wu, Evan Wegener, A. Kropf, Nohor Samad, Simuck Yuk, Difan Zhang, Susan Habas, Theodore Krause, James Harris, Mal-Soon Lee, Vassiliki-Alexandra Glezakou, Roger Rousseau, Andrew Sutton, Zhenglong Li

Research output: Contribution to journalArticlepeer-review

1 Scopus Citations

Abstract

Single-site copper-based catalysts have shown remarkable activity and selectivity for a variety of reactions. However, deactivation by sintering in high-temperature reducing environments remains a challenge and often limits their use due to irreversible structural changes to the catalyst. Here, we report zeolite-based copper catalysts in which copper oxide agglomerates formed after reaction can be repeatedly redispersed back to single sites using an oxidative treatment in air at 550 degrees C. Under different environments, single-site copper in Cu-Zn-Y/deAlBeta undergoes dynamic changes in structure and oxidation state that can be tuned to promote the formation of key active sites while minimizing deactivation through Cu sintering. For example, single-site Cu2+ reduces to Cu1+ after catalyst pretreatment (270 degrees C, 101 kPa H2) and further to Cu0 nanoparticles under reaction conditions (270-350 degrees C, 7 kPa EtOH, 94 kPa H2) or accelerated aging (400-450 degrees C, 101 kPa H2). After regeneration at 550 degrees C in air, agglomerated CuO was dispersed back to single sites in the presence and absence of Zn and Y, which was verified by imaging, in situ spectroscopy, and catalytic rate measurements. Ab initio molecular dynamics simulations show that solvation of CuO monomers by water facilitates their transport through the zeolite pore, and condensation of the CuO monomer with a fully protonated silanol nest entraps copper and reforms the single-site structure. The capability of silanol nests to trap and stabilize copper single sites under oxidizing conditions could extend the use of single-site copper catalysts to a wider variety of reactions and allows for a simple regeneration strategy for copper single-site catalysts.
Original languageAmerican English
Pages (from-to)8280-8297
Number of pages18
JournalJournal of the American Chemical Society
Volume146
Issue number12
DOIs
StatePublished - 2024

NREL Publication Number

  • NREL/JA-5100-88020

Keywords

  • ab initio molecular dynamics
  • catalyst deactivation
  • catalyst regeneration
  • copper catalyst
  • ethanol
  • in-situ STEM
  • olefins
  • redispersion
  • sintering
  • X-ray absorption spectroscopy
  • zeolite

Fingerprint

Dive into the research topics of 'Dynamic Copper Site Redispersion through Atom Trapping in Zeolite Defects'. Together they form a unique fingerprint.

Cite this