Vibrational Study of SOx Adsorption on Pt/SiO2

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• 作者：Djamela Bounechada ; Zhafira Darmastuti ; Mike Andersson ; Lars Ojam盲e ; Anita Lloyd Spetz ; Magnus Skoglundh ; Per-Anders Carlsson
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：December 26, 2014
• 年：2014
• 卷：118
• 期：51
• 页码：29713-29723
• 全文大小：467K
• ISSN：1932-7455

文摘

The formation of ad-SO_x species on Pt/SiO₂ upon exposure to SO₂ in concentrations ranging from 10 to 50 ppm at between 200 and 400 掳C has been studied by in situ diffuse reflectance infrared Fourier transformed spectroscopy. In parallel, first-principles calculations have been carried out to consolidate the experimental interpretations. It was found that sulfate species form on the silica surface with a concomitant removal/rearrangement of silanol groups. Formation of ad-SO_x species occurs only after SO₂ oxidation to SO₃ on the platinum surface. Thus, SO₂ oxidation to SO₃ is the first step in the SO_x adsorption process, followed by spillover of SO₃ to the oxide, and finally, the formation of sulfate species on the hydroxyl positions on the oxide. The sulfate formation is influenced by both temperature and SO₂ concentration. Furthermore, exposure to hydrogen is shown to be sufficiently efficient as to remove ad-SO_x species from the silica surface.