FT-IR studies of the interaction between zeolitic hydroxyl groups and small molecules. 1. Adsorption of nitrogen on H-mordenite at low temperature

Wakabayashi, Fumitaka; Kondo, Junko N.; Wada, Akira; Domen, Kazunari; Hirose, Chiaki

doi:10.1021/j100143a040

Cited by 144 publications

(144 citation statements)

References 7 publications

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“…This results in a reduced contribution of anti-bonding character to the C-O bond, making the bond stronger. This is observed as a large blue shift of the C-O stretching IR band [37,38], as illustrated in figure 5 [39]. When CO is adsorbed on Bro¨nsted acid sites, a red shift of the stretching band of the acidic OH band is observed with a small blue shift of the C-O stretching band.…”

Section: Distinction Of Acid-typementioning

confidence: 83%

“…This is in accord with a decrease in the symmetry of the molecule in the adsorption state. When N 2 is adsorbed on Lewis acid sites, a large blue shift of the N-N stretching band is observed as well as the case of CO [37,38]. Therefore, N 2 can be also used as a probe molecule for characterizing the properties of surfaces…”

Section: Distinction Of Acid-typementioning

confidence: 99%

“…Sulfated zirconia has strong Lewis-acid character [11], and Al 2 O 3 is known to consist mainly of Lewis sites [41]. Although mordenite has a small number of Lewis acid sites at high temperature [37], the acid sites on mordenite are regarded as being of the Bro¨nsted type. When the Lewis acid sites coexist with the Bro¨nsted acid sites, the adsorption of gaseous molecules is predominantly on the Lewis acid sites [15,37,42].…”

Section: Distinction Of Acid-typementioning

confidence: 99%

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Adsorption and desorption of small molecules for the characterization of solid acids

Matsuhashi

Arata

2006

Catal Surv Asia

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The relative acid strength and acid amount of solid acids has been determined from the adsorption and desorption of small molecules, such as argon. The order of activation energy for desorption of Ar from a solid acid, determined using temperatureprogrammed desorption (TPD), is sulfated zirconia > Cs 2.5 H 0.5 PW 12 O 40 > proton-type zeolites > silica-alumina. The adsorption isotherms were analyzed using Langmuir and Henry equations. The Henry-type adsorption isotherms were also analyzed using the theory of Cremer and Flu¨gge. The heat of Ar adsorption was 22 kJ mol )1 for sulfated zirconia and ca. 17 kJ mol )1 for mordenite, ZSM-5, and beta-zeolite. Molybdenum oxides reduced at 623 and 773 K exhibited a large heat of adsorption (19.3 and 19.7 kJ mol )1 , respectively), and these materials are classified as superacids. W-Nb mixed-oxides and tungstated tin oxide (calcined at 1373 K), which are newly developed solid acids, had a heat of adsorption of 18.1 and 16.9 kJ mol )1 , respectively. The type of acid site could be distinguished by comparing the heat of adsorption of Ar and N 2 . Our data indicate that Ar is useful for the characterization of solid acids.

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Section: Distinction Of Acid-typementioning

confidence: 83%

Section: Distinction Of Acid-typementioning

confidence: 99%

Section: Distinction Of Acid-typementioning

confidence: 99%

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Adsorption and desorption of small molecules for the characterization of solid acids

Matsuhashi

Arata

2006

Catal Surv Asia

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“…The temperature was then decreased under hydrogen (deuterium) to room temperature, and the gas phase was evacuated at room temperature. This series of pretreatments does not produce any Lewis acid sites 18) . All organic reagents were purchased from Aldrich and were used as received.…”

Section: Detailed Experimental Procedures 1 1 Sample Preparationmentioning

confidence: 86%

Adsorption of Hydrocarbons and Formation of Carbocations over Zeolites Studied by IR Spectroscopy

Nomura

Shima

2008

J. Jpn. Petrol. Inst.

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Carbocation species are considered to be important intermediates in the reactions of hydrocarbons over zeolites, and the formation mechanism, as well as the reactivity, has been studied mainly by NMR and IR spectroscopy. The present state of knowledge obtained from these studies is summarized, and experimental details of IR methods for the investigation of solid catalysis are described. As an example of IR research on the catalysis of zeolites, recent results on the formation of alkenyl cation species by the reaction of cyclic alkenes with the acidic hydroxyl groups on zeolites are summarized. The formation of alkenyl cation species was observed by adsorption of cycloalkenes on silica _ alumina, HY zeolite, mordenite, H-ZSM-5 and H-beta zeolite, and characterized by IR peaks at 1490-1530 cm -1 and UV-visible peaks at 290-330 nm. Formation of alkoxyl groups in addition to alkenyl cations was observed on H-ZSM-5 with smaller pores and H-beta with weaker acidity zeolites in comparison with HY zeolite.

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“…The heat of adsorption of the adsorbates considered here is typically 1000 cm-l/bond, i.e. about one third of the vibrational quantum [26]: There is sufficient energy in the excited hydroxyl to dissociate the hydrogen bond. Indeed, we observe desorption of nitrogen from the zeolite hydroxyl.…”

Section: The Effect Of the Adsorbate On The Relaxation Ratementioning

confidence: 99%

Dynamical studies of zeolitic protons and interactions with adsorbates by picosecond infrared spectroscopy

Bonn¹,

Bakker²,

Kleyn³

et al. 1997

Applied Surface Science

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FT-IR studies of the interaction between zeolitic hydroxyl groups and small molecules. 1. Adsorption of nitrogen on H-mordenite at low temperature

Cited by 144 publications

References 7 publications

Adsorption and desorption of small molecules for the characterization of solid acids

Adsorption and desorption of small molecules for the characterization of solid acids

Adsorption of Hydrocarbons and Formation of Carbocations over Zeolites Studied by IR Spectroscopy

Dynamical studies of zeolitic protons and interactions with adsorbates by picosecond infrared spectroscopy

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