Generation of active oxygen species on solid surfaces. Opportunity for novel oxidation technologies over zeolites

Panov, G. I.; Uriarte, A.; Rodkin, Mikhail A.; Соболев, В. И.

doi:10.1016/s0920-5861(98)00026-1

Cited by 478 publications

(327 citation statements)

References 85 publications

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“…The main particularity of the oxygen species formed by N 2 O decomposition during its contact with H(Fe)ZSM-5, is a high reactivity in oxidation reactions [14]. In the present study, the activity of (O) ad was characterized by its ability to oxidize CO.…”

Section: Reactivity Of (O) Ad In Co Oxidationmentioning

confidence: 73%

Transient response method for characterization of active sites in HZSM-5 with low content of iron during N2O decomposition

2004

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The surface active Fe-sites in HZSM-5 with low content of iron (<1000 ppm) activated by steaming and high temperature (up to 1323 K) calcination in inert lead to the formation of surface oxygen (O) ad species from N 2 O and were characterized quantitatively by transient response method. Only a part of (O) ad deposited on zeolite by decomposing N 2 O was active in CO oxidation 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 [Fe 2 O 2 H] + -cluster.Zeolite pre-saturated by water vapor at 473-523 K generates (O) ad species from N 2 O completely inactive in the CO oxidation. The total amount of the oxygen, (O) ad , deposited on the pre-saturated by water zeolite corresponds to a half of stoichiometric amount of the surface Fe-atoms and suggests that water blocks a half of the binuclear [Fe 2 O 2 H] + -center, the remaining acting as a single Fe-site.

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Section: Reactivity Of (O) Ad In Co Oxidationmentioning

confidence: 73%

Transient response method for characterization of active sites in HZSM-5 with low content of iron during N2O decomposition

2004

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“…Selective oxidation is one of the most important ways to produce monomers and chemical intermediates and there are wide basic and applied interests in this research area [1,2]. After the truly heterogeneous catalyst, TiO 2 /SiO 2 , was developed by Shell in the 1970s, the selective oxidation on solid catalyst has made great progress using H 2 O 2 or organic hydroper-oxide as oxidants [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Epoxidation of styrene on Si/Ti/SiO2 catalysts prepared by chemical grafting

Yang

Wang

et al. 2000

Applied Catalysis A: General

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“…Important elementary steps of the mechanism can be detected using different catalysts. Iron containing zeolites of MFI type are particularly interesting catalysts for these reactions because they have been successfully applied in the abatement of N 2 O in waste gases as well as in partial oxidations of hydrocarbons with N 2 O [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…(1)), where an atomic, surface bound oxygen species is formed during the interaction of N 2 O with active iron sites in the zeolite Z [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. This step initiates not only the stoichiometric N 2 O decomposition to nitrogen and oxygen, but also provides a selective oxygen species called "␣-oxygen" by Panov and co-workers [3,4,[9][10][11][12]. This oxygen species was found to be very reactive in the oxidation of H 2 , CO, methane and benzene, even at room temperature, and very selective in the hydroxylation of aromatics [3][4][5][6] and the oxidative dehydrogenation of propane [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…This step initiates not only the stoichiometric N 2 O decomposition to nitrogen and oxygen, but also provides a selective oxygen species called "␣-oxygen" by Panov and co-workers [3,4,[9][10][11][12]. This oxygen species was found to be very reactive in the oxidation of H 2 , CO, methane and benzene, even at room temperature, and very selective in the hydroxylation of aromatics [3][4][5][6] and the oxidative dehydrogenation of propane [7,8]. This is schematically shown in Eq.…”

Section: Introductionmentioning

confidence: 99%

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Experimental techniques for investigating the surface oxygen formation in the N2O decomposition on Fe-MFI zeolites

Ateş¹,

Reitzmann²

2007

Chemical Engineering Journal

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Several experimental techniques were used to investigate the formation of surface oxygen in the N 2 O decomposition on an Fe-MFI zeolite. These techniques consisted of multipulse and step experiments as transient methods at ambient pressure and experiments in a closed set-up of Panov and co-workers at strongly reduced pressure. The total amount of surface oxygen determined through multipulse experiments was in the range of the amount obtained in the vacuum set-up at 523 K (40-50 mol O g −1 catalyst ). In contrast, the step technique revealed considerably higher values, up to 110 mol O g −1 catalyst , indicating an accumulation of oxygen in the zeolite. This phenomenon might also be responsible for the observation that higher reaction temperatures increase the total amount of surface oxygen, which can be deposited in the zeolite. In contrast to experiments in the vacuum set-up, the temperature-programmed desorption after multipulse and step experiments shows the presence of various oxygen species differing in thermal stability. The influence of temperature on the rate of surface oxygen formation was determined from step and vacuum experiments. The results of the step experiments lead to a lower activation energy, 14 kJ mol −1 , than the experiments in the vacuum set-up (49 kJ mol −1 ), probably due to sorption and mass transfer effects. Comparing the rate of surface oxygen formation and of total N 2 O decomposition reveals that the former is very fast and not rate determining for the latter. Furthermore, the rate of total N 2 O decomposition seems to be inhibited by adsorbed N 2 O, detected in the transient experiments. This observation is considered in an adequate kinetic model.

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Generation of active oxygen species on solid surfaces. Opportunity for novel oxidation technologies over zeolites

Cited by 478 publications

References 85 publications

Transient response method for characterization of active sites in HZSM-5 with low content of iron during N2O decomposition

Transient response method for characterization of active sites in HZSM-5 with low content of iron during N2O decomposition

Epoxidation of styrene on Si/Ti/SiO2 catalysts prepared by chemical grafting

Experimental techniques for investigating the surface oxygen formation in the N2O decomposition on Fe-MFI zeolites

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