Chemical interactions in multimetal/zeolite catalysts
The mechanisms operating in the formation of bimetal (alloy) particles inside Y zeolites have been studied in detail. The simple view that the more noble metal is reduced first, such that its clusters will serve as nuclei for the reduction of the less noble metal, has been verified for the case of Pd+Ni, but simultaneously it has been shown that two other mechanisms are also contributing. In this research it was of great help that our earlier discovery could be confirmed that zeolite protons selectively oxidize the atoms of the less noble metal in each alloy particle. This leaching'' leads to a situation where all atoms of one metal are present as clusters, while all atoms of the other metal in the same zeolite are present as cations. Leaching has now been confirmed for Pt+Cu, Pd+Cu and Pd+Ni in Y zeolite. In another approach we studied the potential for redispersion of large metal or alloy particles in zeolites, i.e. in situ rejuvenation of catalysts after substantial sintering of the metal. This approach turned out to be very successful. Our strategy is to first oxidize the metal and let the resulting ions disperse in small cages throughout the zeolite matrix. Subsequent reduction under mild conditions results in small metal particles.
- Research Organization:
- Northwestern Univ., Evanston, IL (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-87ER13654
- OSTI ID:
- 5977368
- Report Number(s):
- DOE/ER/13654-5; ON: DE92005537
- Country of Publication:
- United States
- Language:
- English
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Chemical interactions in multimetal/zeolite catalysts
Chemical interactions in multimetal/zeolite catalysts
Related Subjects
400201* -- Chemical & Physicochemical Properties
ALLOY SYSTEMS
BINARY ALLOY SYSTEMS
CATALYSTS
COHERENT SCATTERING
DIFFRACTION
DISSOLUTION
DOCUMENT TYPES
ELECTRON SPECTROSCOPY
FABRICATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
LEACHING
MATERIALS
MINERALS
PHOTOELECTRON SPECTROSCOPY
PROGRESS REPORT
REGENERATION
SCATTERING
SEPARATION PROCESSES
SILICATE MINERALS
SINTERING
SPECTROSCOPY
X-RAY DIFFRACTION
ZEOLITES