ISSN:
1572-879X
Schlagwort(e):
Pt-Cr alloy
;
ZSM-5
;
CO adsorption
;
FTIR
;
HRTEM
;
nanodiffraction
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract The catalysts Pt/HZSM-5 and Pt-Cr/HZSM-5 are characterized by FTIR spectroscopy using CO as a probe molecule, and by transmission electron microscopy. The major fraction of the metal phase detected in the micrographs exhibits particles in the range of 1–3 nm uniformly distributed in the zeolite crystals. Nanodiffraction analysis of single particles confirmed the formation of fcc Pt-Cr alloy with lattice constanta = 0.386 nm. The infrared spectra at 300 K exhibit bands assigned to CO linearly bonded to zeolite-hosted metal particles at 2089 cm−1 for Pt/HZSM-5, and at 2120 and 2092 cm−1 for Pt-Cr/HZSM-5. The temperature increase to 610 K resulted in a strong shift of the 2089 cm−1 band for Pt/HZSM-5 by 25 cm−1 and a slight shift of the corresponding bands for Pt-Cr/HZSM-5 by 6 cm−1. The differences are referred to different electron backdonation capacities of the CO binding Pt surface atoms of the metal particles. The lower capacity for the Pt-Cr/HZSM-5 sample is due to alloying in the metal particles.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00811360
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