Study of the surface properties of a solid solution of vanadium in SnO2 by IR spectroscopy

Давыдов, А. А.; Shepot'ko, M. L.

doi:10.1007/bf00530267

Cited by 4 publications

(5 citation statements)

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“…In Figure A, the bands at 2187 and 2090 cm -1 can be accordingly assigned to Fe(III) and Fe(II) sites. However, their intensities depends on the coordination status of the iron cations which determines the ability of electron donation-acceptance between iron and CO. Harrison et al and Davydov et al reported that no bands of CO adsorbed on the cationic iron sites of Fe(III)/SnO 2 , Fe(III)/zeolite Y and oxidized Fe 2 O 3 /Al 2 O 3 can be observed because of the saturated coordination of the cations. On the unsupported Fe sample, the coordination of the cationic iron may also be nearly saturated and, therefore, only weak bands of CO adsorbed on Fe(III) and Fe(II) sites are detected.…”

Section: Resultsmentioning

confidence: 99%

“…CO adsorption on metallic iron surfaces of supported catalysts and evaporated microcrystals and single crystals exposing well-defined planes have been extensively explored by infrared and high-resolution electron energy loss spectroscopies. ,,,,− The bands with the frequencies of 2130−2000 cm -1 have been attributed to the linearly adsorbed CO on tops of Fe(0) sites, e.g., on the top sites of the first layer of Fe (111), and the bands of 2000−1880 cm -1 to the 2-fold bridge-bonded CO on second layer shallow hollow sites and those of 1880−1650 cm -1 to the multiply bridge-bonded CO on deep hollow sites. − From the spectra shown in Figure , mainly three kinds of adsorbed CO on the syngas-reduced Fe sample are detected, two linear (2043 and 2025 cm -1 ) and one bridged (1896 cm -1 ). Besides, Fe(II) species are also indicated by the band 2157 cm -1 , which may arise from the oxidation of Fe(0) by the oxygen migrating from the lattice during heating in the absence of reducing gas.…”

Section: Resultsmentioning

confidence: 99%

“…To gain the knowledge of microstructures and catalytic properties of the catalysts, a large number of scientific studies has been undertaken by using a variety of experimental techniques. − Among them, vibrational spectroscopies coupled with probe molecule adsorption are the surface-sensitive ones for investigations of properties of solid surfaces. The configurations of CO and NO adsorbed on iron single crystals of different exposed planes have been extensively studied by high-resolution electron energy loss spectroscopy. − Adsorption of CO and NO on iron-based catalysts with iron species supported on, e.g., Al 2 O 3 , SiO 2 , ZrO 2 and MgO has also been widely studied by infrared spectroscopy. ,,,,− For unsupported iron catalysts, however, the reports regarding to the investigations of their adsorption properties by infrared spectroscopy are very rare.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption Properties of Iron and Iron−Manganese Catalysts Investigated by in-situ Diffuse Reflectance FTIR Spectroscopy

2000

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The adsorption properties of the precipitated Fe and FeMn catalysts were studied by in-situ diffuse reflectance FTIR using CO, NO and CO + H 2 (syngas) as probe molecules. CO and NO adsorption on the oxidized Fe sample reveals the presence of Fe(III) and Fe(II) on the surfaces. On the H 2 -reduced Fe sample, the adsorbed probes mainly dissociate because of the high reactivity of the formed fine Fe(0) particles. Upon reduction in syngas, significant amount of carbonaceous and hydrocarbon fragment species is deposited on the surfaces which prevents from the access of the probe molecules to the metallic iron species. But, the spectra recorded from the thermal desorption of the adsorbed syngas displays three desorption bands with their frequencies nearly coinciding with those of the C-O vibrations in Fe 3 (CO) 12 iron carbonyl, claiming that the size of the formed Fe(0) particles is indeed very small. With addition of manganese to the sample, the Fe(II) species dominates on the surface. After reduction either in H 2 or in syngas, the Fe(II) and Fe(0) sites are indicated by NO adsorption. CO and syngas adsorption gives rise to a large number of distinct bands corresponding to linear and bridged adsorption species. The bands of CO adsorbed on the deep hollow sites of Fe(0) implies that the size of the Fe(0) particles formed on the reduced FeMn sample is larger than that on the reduced Fe one. The adsorption features of the Fe(0) particles formed on the FeMn samples reduced either in syngas or in H 2 (without formation of iron carbides) are quite similar, suggesting that the adsorption properties of the reduced FeMn samples are not determined by the formed iron carbides, but rather by surface Fe(0) particles of different sizes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Adsorption Properties of Iron and Iron−Manganese Catalysts Investigated by in-situ Diffuse Reflectance FTIR Spectroscopy

2000

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“…It can be seen from Figure that after adsorption of CO in the spectra of the samples, bands with maxima at 2174 and 2188 cm –1 appear, which completely disappear after desorption of CO (evacuation of the samples at room temperature for 30 min). According to Davydov and Hadjiivanov, they can be attributed to weakly bound complexes of CO with low-coordinated nickel ions Ni 2+ . The shift of the CO band by 14 cm –1 toward higher frequencies in the spectrum of the 10% Ni/Al 2 O 3 -F sample compared to the band in the spectrum of the 10% Ni/Al 2 O 3 sample indicates a certain decrease in the electron density on cations of divalent nickel.…”

Section: Resultsmentioning

confidence: 99%

Nickel–Alumina Catalysts in the Reaction of Carbon Dioxide Re-Forming of Methane under Thermal and Microwave Heating

Kustov

Тарасов

Ткаченко

et al. 2017

Ind. Eng. Chem. Res.

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The activity of 10% Ni/Al 2 O 3 and 10% Ni/Al 2 O 3 -F catalysts prepared by sol−gel method was studied in the carbon dioxide methane re-forming under thermal and microwave heating. It is found that replacement of thermal for microwave heating results in stable activity restoration with substantial suppression of coke formation. Thermodynamic calculation of reactants and products equilibrium concentrations in the main and side reactions, including soot formation, shows that in the microwave-activated process of carbon dioxide methane reforming on 10% Ni/Al 2 O 3 -F the reactions of carbon and perhaps methane steam reforming are significantly intensified. Physicochemical methods (DRIFT spectroscopy, adsorption measurements by the BET method) revealed differences in surface properties of catalysts (specific surface area, pore volume, acidity), as well as electronic state of nickel. The results obtained demonstrate the perspectives of the microwave activation of the reactions of carbon dioxide re-forming not only in the case of methane but also in the cases of ethane and propane, where the problem of coke formation and catalyst deactivation is even more significant.

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“…A similar series of bands was observed in the spectrum of (Zn,Mn)Fe 2 O 4 spinel [ 28 ]. For the FP SCWA-TsL sample, a distinctive feature of its spectrum is a clear-cut resolution of the bands at 945 and 886 cm −1 assigned to stretching vibrations of Cr–O when the chromium atom is coordinatively saturated [ 32 ]. An intense band centered at 597 cm −1 with a shoulder at 615 cm −1 is a combined one and corresponds to vibrations of Fe–O bonds in both a spinel structure and free iron(III) oxides.…”

Section: Discussionmentioning

confidence: 99%

Nanostructured Polyphase Catalysts Based on the Solid Component of Welding Aerosol for Ozone Decomposition

Rakitskaya¹,

Truba²,

Еннан³

et al. 2015

Nanoscale Res Lett

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Samples of the solid component of welding aerosols (SCWAs) were obtained as a result of steel welding by ANO-4, TsL‑11, and UONI13/55 electrodes of Ukrainian manufacture. The phase compositions of the samples, both freshly prepared (FP) and modified (M) by water treatment at 60 °C, were studied by X-ray phase analysis and IR spectroscopy. All samples contain magnetite demonstrating its reflex at 2θ ~ 35° characteristic of cubic spinel as well as manganochromite and iron oxides. FP SCWA-TsL and FP SCWA-UONI contain such phases as СaF2, water-soluble fluorides, chromates, and carbonates of alkali metals. After modification of the SCWA samples, water-soluble phases in their composition are undetectable. The size of magnetite nanoparticles varies from 15 to 68 nm depending on the chemical composition of electrodes under study. IR spectral investigations confirm the polyphase composition of the SCWAs. As to IR spectra, the biggest differences are apparent in the regions of deformation vibrations of M–O–H bonds and stretching vibrations of M–O bonds (M–Fe, Cr). The catalytic activity of the SCWAs in the reaction of ozone decomposition decreases in the order SCWA-ANO > SCWA-UONI > SCWA-TsL corresponding to the decrease in the content of catalytically active phases in their compositions.

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Study of the surface properties of a solid solution of vanadium in SnO2 by IR spectroscopy

Cited by 4 publications

References 2 publications

Adsorption Properties of Iron and Iron−Manganese Catalysts Investigated by in-situ Diffuse Reflectance FTIR Spectroscopy

Adsorption Properties of Iron and Iron−Manganese Catalysts Investigated by in-situ Diffuse Reflectance FTIR Spectroscopy

Nickel–Alumina Catalysts in the Reaction of Carbon Dioxide Re-Forming of Methane under Thermal and Microwave Heating

Nanostructured Polyphase Catalysts Based on the Solid Component of Welding Aerosol for Ozone Decomposition

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