Pyridine-TiO2 surface interaction as a probe for surface active centers analysis

Bezrodna, T.; Puchkovska, G.; Shimanovska, V.; Chashechnikova, I. T.; Khalyavka, Т. A.; Baran, J.

doi:10.1016/s0169-4332(03)00346-5

Cited by 127 publications

(90 citation statements)

References 16 publications

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“…The bare TiO 2 showed the n(OH) stretching bands in the region between 3750 and 3300 cm À1 and a weak band at 1638 cm À1 , corresponding to hydroxyl groups on the TiO 2 nanoparticles surface [32]. The infrared absorption bands between 400 and 800 cm À1 assigned to the vibrations of Ti-O and Ti-O-Ti framework bonds [33]. The FTIR spectrum of PLA-grafted TiO 2 showed the n(CH) stretching vibration of the -CH 2 -and -CH 3 groups at 2979, 2927 and 2875 cm À1 and carboxyl group at 1760 cm À1 .…”

Section: Resultsmentioning

confidence: 99%

Preparation and characterization of poly(lactic acid)-grafted TiO2 nanoparticles with improved dispersions

Luo

Wang

et al. 2009

Applied Surface Science

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Section: Resultsmentioning

confidence: 99%

Preparation and characterization of poly(lactic acid)-grafted TiO2 nanoparticles with improved dispersions

Luo

Wang

et al. 2009

Applied Surface Science

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“…Bezrodna et al [43,44] have shown that at least two types of energy-nonequivalent active centers can be distinguished on the TiO 2 surface. The first one is the band at approximately 3411 cm…”

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confidence: 99%

Gas‐Phase Photooxidation of Alkenes by V‐Doped TiO₂‐MCM‐41: Mechanistic Insights of Ethylene Photooxidation and Understanding the Structure–Activity Correlation

Bhattacharyya

Varma

Tripathi

et al. 2011

Chemistry A European J

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Nanoparticles of Ti(0.95)V(0.05)O(2) were found to be impregnated in the hexagonal channels of the MCM-41 host, with a distribution of some particles on the surface, thus leading to an effective variation in the particle size as a function of loading host MCM-41 matrix. These catalysts were subjected to the photocatalytic degradation of alkenes under the ambient conditions in which the photocatalytic activity varied as a function of the loading percentage of Ti(0.95)V(0.05)O(2) in the host MCM-41.This is explained in light of the structure-activity correlation, and the better catalytic activity can be attributed to an electronic interaction between the host and guest molecules, as established from X-ray photoelectron spectroscopy. To understand the mechanistic aspect of the photooxidation of ethylene on the vanadium-doped titania dispersed in the MCM-41 matrix, extensive in situ FTIR experiments were undertaken. The intermediate species produced on bare Ti(0.95)V(0.05)O(2) are different from that produced on the Ti(0.95)V(0.05)O(2)/MCM-41 surface. Moreover, different intermediates were produced during ethylene oxidation under UV and visible irradiation, thus leading to different rates. The ethylene decomposition over bare Ti(0.95)V(0.05)O(2) occurs by means of formation of ethoxy groups, transformed to acetaldehyde or enolates, subsequently to acetates, and then to CO(2) under both UV and visible irradiation. However, in the case of Ti(0.95)V(0.05)O(2)/MCM-41 catalyst with UV irradiation, the adsorbed acetaldehyde thus formed undergoes aldol condensation over the Lewis acid sites to lead to the formation of crotonaldehyde, which is subsequently oxidized to acetate and consequently to CO(2). It was observed that during visible irradiation labile ethyl acetate is produced either by the Tischenko reaction or by the reaction between the labile acetic acid and the unreacted ethoxy groups. The ethyl acetate produces acetic acid monomer, which is oxidized to CO(2). Furthermore, in this work the effects of particle size on the intermediate species were also studied.

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“…Simultaneously, an isosbestic point on the bridging-OH TiO 2 vibration, probably related to the displacement of water molecules by cyclohexane molecules, can be observed in the range 3600-3750 cm and a strong broad absorption ranging from 3000 to 3500 cm −1 [32]. However, these signals are not visible because the main phenomenon is the appearance of an organo-sulfur compound (found at ~1354 cm −1 ) resulting from a surface reaction between sulfate and adsorbed cyclohexane that may have determined the loss of hydroxyls bonded with sulfate.…”

Section: Drifts Analysismentioning

confidence: 87%

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

et al. 2013

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Abstract:In this work, the results of gas phase cyclohexane photocatalytic oxidative dehydrogenation on MoO x /SO 4 /TiO 2 catalysts with DRIFTS analysis are presented. Analysis of products in the gas-phase discharge of a fixed bed photoreactor was coupled with in situ monitoring of the photocatalyst surface during irradiation with an IR probe. An interaction between cyclohexane and surface sulfates was found by DRIFTS analysis in the absence of UV irradiation, showing evidence of the formation of an organo-sulfur compound. In particular, in the absence of irradiation, sulfate species initiate a redox reaction through hydrogen abstraction of cyclohexane and formation of sulfate (IV) species. In previous studies, it was concluded that reduction of the sulfate (IV) species via hydrogen abstraction during UV irradiation may produce gas phase SO 2 and thereby loss of surface sulfur species. Gas phase analysis showed that the presence of MoO x species, at same sulfate loading, changes the selectivity of the photoreaction, promoting the formation of benzene. The amount of surface sulfate influenced benzene yield, which decreases when the sulfate coverage is lower. During irradiation, a strong deactivation was observed due to the poisoning of the surface by carbon deposits strongly adsorbed on catalyst surface.

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Pyridine-TiO2 surface interaction as a probe for surface active centers analysis

Cited by 127 publications

References 16 publications

Preparation and characterization of poly(lactic acid)-grafted TiO2 nanoparticles with improved dispersions

Preparation and characterization of poly(lactic acid)-grafted TiO2 nanoparticles with improved dispersions

Gas‐Phase Photooxidation of Alkenes by V‐Doped TiO₂‐MCM‐41: Mechanistic Insights of Ethylene Photooxidation and Understanding the Structure–Activity Correlation

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

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Pyridine-TiO2 surface interaction as a probe for surface active centers analysis

Cited by 127 publications

References 16 publications

Preparation and characterization of poly(lactic acid)-grafted TiO2 nanoparticles with improved dispersions

Preparation and characterization of poly(lactic acid)-grafted TiO2 nanoparticles with improved dispersions

Gas‐Phase Photooxidation of Alkenes by V‐Doped TiO2‐MCM‐41: Mechanistic Insights of Ethylene Photooxidation and Understanding the Structure–Activity Correlation

Investigation of the Deactivation Phenomena Occurring in the Cyclohexane Photocatalytic Oxidative Dehydrogenation on MoOx/TiO2 through Gas Phase and in situ DRIFTS Analyses

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Gas‐Phase Photooxidation of Alkenes by V‐Doped TiO₂‐MCM‐41: Mechanistic Insights of Ethylene Photooxidation and Understanding the Structure–Activity Correlation