The surface active Fe-sites in HZSM-5 with low content of iron (<1000 ppm) activated by steaming and high temp. (up to 1323 K) calcination in inert lead to the formation of surface oxygen (O)ad species from N2O and were characterized quant. by transient response method. Only a part of (O)ad deposited on zeolite by decompg. N2O was active in CO oxidn. at 523 K. A binuclear Fe-center is suggested as an active center, featuring a \"diamond core\" structure, similar to that of the monooxygenase enzyme. The active O-atoms were assigned to the paired terminal oxygen atoms each bound to one Fe-site in the binuclear [Fe2O2H]+-cluster. Zeolite pre-satd. by water vapor at 473-523 K generates (O)ad species from N2O completely inactive in the CO oxidn. The total amt. of the oxygen, (O)ad, deposited on the pre-satd. by water zeolite corresponds to a half of stoichiometric amt. of the surface Fe-atoms and suggests that water blocks a half of the binuclear [Fe2O2H]+-center, the remaining acting as a single Fe-site. [on SciFinder (R)]
Title
Transient response method for characterization of active sites in HZSM-5 with low content of iron during N2O decomposition
Published in
Catalysis Today
Volume
91-92
Pages
165-170
Date
2004
ISSN
0920-5861
Note
CAN 141:77445
67-3
Catalysis, Reaction Kinetics, and Inorganic Reaction Mechanisms
Laboratory of Chemical Reaction Engineering,Swiss Federal Institute of Technology, LGRC-EPFL,Lausanne,Switz.
Journal
written in English.
17778-80-2 (Atomic oxygen) Role: CPS (Chemical process), FMU (Formation, unclassified), PEP (Physical, engineering or chemical process), PRP (Properties), RCT (Reactant), FORM (Formation, nonpreparative), PROC (Process), RACT (Reactant or reagent) (adsorbed; transient response method for characterization of active sites in HZSM-5 with low content of iron during N2O decompn.); 7732-18-5 (Water) Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), PRP (Properties), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (adsorbed; transient response method for characterization of active sites in HZSM-5 with low content of iron during N2O decompn.); 7439-89-6 (Iron) Role: CAT (Catalyst use), PRP (Properties), USES (Uses) (transient response method for characterization of active sites in HZSM-5 with low content of iron during N2O decompn.); 630-08-0 (Carbon monoxide); 10024-97-2 (Nitrous oxide) Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), PRP (Properties), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (transient response method for characterization of active sites in HZSM-5 with low content of iron during N2O decompn.)
Record creation date
2006-04-18
