Enhanced activity of sol–gel prepared SnOx–TiO2 in photocatalytic methanol reforming

Authors:  Katalin Majrik, Emília Tálas, Zoltán Pászti, István Sajó, Judith Mihály, László Korecz, Eszter Drotár, András Tompos

Abstract:
Objective: In this contribution a simple method is elaborated for the preparation of Pt/SnOx–TiO₂ catalysts which are active in the photocatalytic reforming of methanol. The region of low tin content (Sn/Ti atomic ratio: 0–0.015) is explored. Tin content related activity changes of the catalysts are discussed in terms of the results of structural characterization.
       Methods: Tin-modified anatase TiO₂ samples were obtained from sol–gel method by use of Tiisopropoxide, SnCl₄ or Sn(OBu)₄ and citric acid in absolute ethanol solution followed by calcinations at 400 ^◦C in air. After loading Pt by impregnation the catalytic activity has been tested irradiating the slurry of the catalysts suspended in mixture of water and methanol by means of two different light sources, one working exclusively in the visible region and one in a broader spectral range including a UV-component, respectively. Hydrogen production activity has been correlated with structural data obtained from different characterization techniques such as ESR spectroscopy, XRD, XPS, SEM and Raman spectroscopy as well as diffuse reflectance UV–Vis spectrophotometry.
      Results: According to ESR spectroscopic measurements the presence of oxygen vacancies was responsible for the slight visible light absorption. XRD, XPS, SEM and Raman spectroscopic results indicated that highly dispersed SnOx accumulated in the surface region of TiO₂, no tin incorporation into the lattice was observed. The fundamental band gap was not influenced by the presence of tin. Loading of the tinmodified samples by 0.5 wt% Pt increased the hydrogen production in comparison to 0.5 wt% Pt/TiO₂ samples.
       Conclusions: The improvement in the catalytic activity was explained by formation of new tin related charge carrier traps leading to (i) prevention of electron–hole recombination and (ii) additional modification of the adsorption of reactants. Details of the two different working mechanisms are described. Practice implication: The increased hydrogen production over the tin modified samples provides a promising step toward practical usage of light for hydrogen production.

Keywords:
TiO₂
SnO₂
Sol–gel method
Hydrogen production
Methanol Photocatalytic reforming

Published in: Applied catalysis A: General  (Volume 466, Pages 1-314, 10 September 2013)

Publisher: Elsevier  

ISSN Information: 0926-860X

Enhanced activity of sol–gel prepared SnOx–TiO2 in photocatalytic methanol reforming

Bình luận của bạn

*

*

*

*

 Captcha

Gửi bình luận nhập lại