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Photocatalytic methanol assisted production of hydrogen with simultaneous degradation of methyl orange

Paper ID Volume ID Publish Year Pages File Format Full-Text
39004 45800 2016 7 PDF Available
Title
Photocatalytic methanol assisted production of hydrogen with simultaneous degradation of methyl orange
Abstract

•Pt/TiO2 is effective in photocatalytic methanol reforming to hydrogen.•Methyl orange (MO) deteriorates photocatalytic methanol reforming activity.•The NN bond of MO is hydrogenated by photo-excited Pt/TiO2.•O2 inhibits NN hydrogenation and photocatalytic methanol reforming.•Simultaneous methanol assisted hydrogen formation and dye degradation in not feasible.

Platinized TiO2 prepared by photodeposition was evaluated for activity in the simultaneous conversion of methyl orange (MO), and methanol assisted formation of hydrogen. Low concentrations of MO were found ineffective for generation of hydrogen in measurable quantities upon illumination of Pt/TiO2 in water. On the other hand, methanol induced hydrogen formation was significant. Surprisingly, when methyl orange was added to the methanol/water solution, hydrogen formation was significantly suppressed. The origin of this detrimental effect of methyl orange lies in the strong and preferred adsorption of the dye on the Pt sites of the catalyst, resulting in hydrogenation of the azo bond and suppression of the catalyzed formation of hydrogen. The hydrogenation of the azo bond is corroborated by dis-colorization of the solution and the observation of a mass fragment in LC–MS analysis corresponding to a hydrogenated product of MO (m/z = 172). Similar to hydrogen formation, dye dis-colorization is stimulated by the presence of methanol, without the formation of new chemical compounds, confirming the role of methanol as a hole scavenger in the photocatalytic processes. Finally the presence of oxygen (in lean conditions) delays dye hydrogenation and hydrogen formation, which we discuss is due to oxygen adsorption and formation of superoxide anions over the Pt sites (leading to oxidation of methanol), which is preferred over NN bond hydrogenation, and proton reduction.

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Keywords
Photocatalysis; Hydrogen; Platinum; Titanium dioxide; Methyl orange; Methanol; Decontamination; Oxidation; Anaerobic conditions
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 518, 25 May 2016, Pages 206–212
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us