In situ IR study of adsorbed species and photogenerated electrons during photocatalytic oxidation of ethanol on TiO2

Yu, Zhiqiang; Chuang, Steven S. C.

doi:10.1016/j.jcat.2006.11.022

Cited by 139 publications

(101 citation statements)

References 46 publications

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“…Formate has been identified as a potential intermediate in methanol synthesis catalysts, which suggests that at a reaction temperature of 180°C, the addition of Fe to Rh/ TiO 2 improves the catalyst's ability to produce methanol. This is further supported by the appearance of two peaks in the region 1120-1045 cm -1 , which are the C-O stretches of mono-and bi-dentate adsorbed methoxy species [39,40]. Formate has also been proposed as an intermediate in the formation of acetate/ethanol on Rh-MnO/NaY catalysts [41].…”

Section: Co Hydrogenation On Ferh/tio 2 and Ferh/ Ceomentioning

confidence: 77%

Infrared Spectroscopy Investigation of Fe-Promoted Rh Catalysts Supported on Titania and Ceria for CO Hydrogenation

Magee¹,

Palomino²,

White³

2016

Catal Lett

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The nature of the promotional effect of Fe addition to Rh/TiO 2 and Rh/CeO 2 catalysts for CO hydrogenation was investigated using FT-IR spectroscopy in an ultrahigh vacuum compatible transmission IR cell. CO adsorption experiments on Rh and FeRh showed vibrational signatures characteristic of linear and bridge bound CO on Rh 0 as well as geminal-dicarbonyl species associated with Rh ? . Compared to TiO 2 , the CeO 2 -supported catalysts show increased dispersion, reflected by decreased particle size, and a lower signal for linear versus geminal-dicarbonyl bonded CO . The absorption frequencies for CO on Rh/CeO 2 are also redshifted relative to Rh/ TiO 2 , which results from a weaker Rh-CO interaction, likely due to the increased reducibility of the CeO 2 support. Upon addition of Fe, a new spectral feature is observed and attributed to CO bound to Rh in close contact with Fe, likely as a surface alloy. CO hydrogenation on (Fe)Rh catalysts on both supports was also studied. Compared to bare Rh, Fe containing catalysts promote formate and methoxy species on the surface at lower temperature (180°C), which suggests an enhancement in methanol selectivity by Fe addition. At higher temperatures (220°C), the spectral features appear similar, further confirming the role of Fe as a disrupter of large Rh 0 crystallites and regulator of CO dissociation and CH 4 formation. Graphical Abstract

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Section: Co Hydrogenation On Ferh/tio 2 and Ferh/ Ceomentioning

confidence: 77%

Infrared Spectroscopy Investigation of Fe-Promoted Rh Catalysts Supported on Titania and Ceria for CO Hydrogenation

Magee¹,

Palomino²,

White³

2016

Catal Lett

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“…1. Alcohols are known as hole scavenges [22][23][24]. Ethanol is oxidized to acetaldehyde via two electron injection into the VB [25] with a time scale in the nanosecond range [26].…”

Section: Resultsmentioning

confidence: 99%

Comparing Pt/SrTiO3 to Rh/SrTiO3 for hydrogen photocatalytic production from ethanol

Ahmed

Odedairo

Labis³

et al. 2013

Appl Petrochem Res

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Photocatalytic hydrogen production from ethanol as an example of biofuel is studied over 0.5 wt% Rh/ SrTiO 3 and 0.5 wt% Pt/SrTiO 3 perovskite materials. The rate of hydrogen production, r H2 , over Pt/SrTiO 3 is found to be far higher than that observed over Rh/SrTiO 3 (4 9 10 -6 mol of H 2 g catal.-1 min -1 (1.1 9 10 -6 mol of H 2 m catal.-2 min -1 ) compared to 0.7 9 10 -6 mol of H 2 g catal.-1 min -1 (5.5 9 10 -8 mol of H 2 m catal.-2 min -1 ), respectively, under UV excitation with a flux equivalent to that from the sun light (ca. 1 mW cm -2 ). Analyses of the XPS Rh3d and XPS Pt4f indicate that Rh is mainly present in its ionic form (Rh 3? ) while Pt is mainly present in its metallic form (Pt 0 ). A fraction of the non-metallic state of Rh in the catalyst persisted even after argon ion sputtering. The tendency of Rh to be oxidized compared to Pt might be the reason behind the lower activity of the former compared to the later. On the contrary, a larger amount of methane are formed on the Rh containing catalyst compared to that observed on the Pt containing catalyst due to the capacity of Rh to break the carbon-carbon bond of the organic compound.

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“…Similar to photo-fermentation where enzyme is used to catalyze the conversion, solar energy is again utilized to offer sufficient power to produce hydrogen from ethanol under the facilitation of inorganic catalyst. Among many catalysts documented in the literature, TiO 2 [8][9][10] is the most commonly used catalyst base due to its excellent photoreactivity which has a suitable band gap for efficient light photon absorption. Upon radiation, the electron contained in a semiconductor such as TiO 2 will be excited and transferred from valence band to conduction band, resulting in the creation of an electron-hole pair and in turn providing an active site for redox reaction.…”

Section: Photocatalytic Hydrogen Productionmentioning

confidence: 99%

Catalytic Hydrogen Production from Bioethanol

Song¹

2012

Bioethanol

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In situ IR study of adsorbed species and photogenerated electrons during photocatalytic oxidation of ethanol on TiO2

Cited by 139 publications

References 46 publications

Infrared Spectroscopy Investigation of Fe-Promoted Rh Catalysts Supported on Titania and Ceria for CO Hydrogenation

Infrared Spectroscopy Investigation of Fe-Promoted Rh Catalysts Supported on Titania and Ceria for CO Hydrogenation

Comparing Pt/SrTiO3 to Rh/SrTiO3 for hydrogen photocatalytic production from ethanol

Catalytic Hydrogen Production from Bioethanol

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