Copper sites in zeolites - quantitative IR studies

Góra‐Marek, Kinga; Palomares, Emilio; Glanowska, Anna; Sadowska, K.; Dátka, Jerzy

doi:10.1016/j.micromeso.2012.06.029

Cited by 36 publications

(38 citation statements)

References 26 publications

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“…Normally, the reduction of metal cations in zeolites by hydrogen produces metal clusters and protons. For CuY [ 20 ] and CuZSM-5 [ 29 ] zeolites, the reduction of Cu ions by hydrogen resulted in the formation of Cu 0 (Cu 0 -CO IR bands 2124 cm −1 for CuZSM-5 and 2108 cm −1 for CuY). In our case, these bands were not observed ( Figure 4 ).…”

Section: Resultsmentioning

confidence: 99%

“…The choice of CO as a probe molecule for Cu ions is implied from the existence of a characteristic carbonyl frequency shift, which depends strictly on the copper coordination environment, as well as the oxidation state [ 14 , 15 , 16 ]. In the case of Cu 2+ cations, the CO-IR analysis is insufficient, thus complementary techniques such as Electron Paramagnetic Resonance (EPR) [ 17 , 18 , 19 ], X-ray photoelectron spectroscopy (XPS) [ 20 , 21 , 22 ] and temperature-programmed reduction (TPR) [ 20 , 23 , 24 , 25 , 26 ], as well as IR studies of NO sorption, are needed to receive a detailed characterization of the oxidation state and properties of Cu in zeolites under various red-ox conditions, e.g., [ 27 , 28 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

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Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

et al. 2020

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The process of reduction (by hydrogen and ethanol) and oxidation (by oxygen and NO) of Cu sites in dealuminated faujasite-type zeolites (of Si/Al = 31) was studied by infrared (IR) spectroscopy with CO (for Cu+) and NO (for Cu2+) as probe molecules. Two zeolites were studied: one of them contained mostly Cu+exch., whereas another one contained mostly Cu2+ and Cu+ox. The susceptibility of various forms of Cu for reduction were investigated. IR experiments of CO sorption evidenced that Cu+ox. was more prone for the reduction than Cu+exch. According to NO sorption studies, Cu2+exch. was reduced in the first order before Cu2+ox. Ethanol reduced mostly Cu2+ and, also, some amounts of Cu+. The treatment with oxygen caused the oxidation of Cu+ (both Cu+exch. and Cu+ox.) to Cu2+. The adsorption of NO at 190K produced Cu+(NO)2 dinitrosyls, but heating to room temperature transformed dinitrosyls to mononitrosyls and increased the Cu2+ content.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

et al. 2020

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“…Such opportunity can be offered by IR spectroscopy when carbon monoxide as a probe molecule is employed. Adsorption of carbon monoxide at room temperature results in the saturation of only Cu + cations and the monocarbonyl bands appeared in the 2160-2140 cm À1 wavenumber region [35].…”

Section: The Quantitative Measurements Of Co Adsorptionmentioning

confidence: 99%

“…The concentration of Cu + accessible to CO was calculated from the maximum integrated intensity of the Cu + (CO) bands in the spectra recorded upon the adsorption of CO in excess at room temperature and subsequent removal of physisorbed CO molecules at the same temperature. The value of the molar absorptivity (1.1 cm 2 /mmol [35] or 16.5 cm/mmol (SI in ref. [40])) of Cu + (CO) band was previously determined in our laboratory, during an experiment in which measured doses of CO were sorbed in zeolite CuZSM-5.…”

Section: The Quantitative Measurements Of Co Adsorptionmentioning

confidence: 99%

Ethene and ethyne molecules interacting with Cu+ sites in zeolites—Quantitative infrared spectroscopic studies

Tarach

Walas

Dátka

et al. 2015

Vibrational Spectroscopy

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“…In line with recent studies [37,41], band at 2201 cm -1 represent Cu(II)-CO adducts, where CO is adsorbed on isolated copper (II) species. Gora-Marek et al [47] indicated appearance of 2122 cm -1 bands as a result of weak Cu(0)-CO interactions, however due to the application of the oxidative atmosphere for sample pre-treatment we rather opted for Giordanino et al [48] explanation, in which they attributed this band to interaction of CO with extra-framework Cu(I) species.…”

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confidence: 99%

Effect of postsynthesis preparation procedure on the state of copper in CuBEA zeolites and its catalytic properties in SCR of NO with NH3

Baran

Averseng

Wierzbicki

et al. 2016

Applied Catalysis A: General

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International audienceCopper-containing BEA zeolites, Cu2.0SiBEA and Cu2.0HAlBEA, with 2 wt % of Cu were prepared by a two-step postsynthesis method and a conventional wet impregnation, respectively. These zeolites were characterized by XRD, DR UV–vis, EPR, FTIR and TPR physicochemical techniques. The incorporation of Cu into framework of SiBEA was evidenced by XRD. The state of copper in both zeolites was investigated by DR UV–vis and EPR. The acidity of Cu2.0SiBEA and Cu2.0HAlBEA was determined by FTIR of adsorbed CO and pyridine. The reducibility of the Cu species present in both zeolites was studied by TPR and their catalytic properties were investigated in selective catalytic reduction of NO with NH3. Both Cu2.0SiBEA and Cu2.0HAlBEA zeolite catalysts showed very high activity in this reaction with the NO conversion higher than 80% and N2 selectivity higher than 95% in the temperature range between 473 and 623 K. The higher NO conversion and N2 selectivity in SCR of NO with ammonia at the high temperature range for the Cu2.0HAlBEA than for Cu2.0SiBEA suggest that the strong Brønsted and Lewis acidic sites related to the framework and extra-framework aluminum atoms play an important role in SCR of NO process

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Copper sites in zeolites - quantitative IR studies

Cited by 36 publications

References 26 publications

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

Reduction and Oxidation of Cu Species in Cu-Faujasites Studied by IR Spectroscopy

Ethene and ethyne molecules interacting with Cu+ sites in zeolites—Quantitative infrared spectroscopic studies

Effect of postsynthesis preparation procedure on the state of copper in CuBEA zeolites and its catalytic properties in SCR of NO with NH3

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