کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
57573 47123 2008 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
H2-induced promotion of CO oxidation over unsupported gold
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
H2-induced promotion of CO oxidation over unsupported gold
چکیده انگلیسی

The kinetics and mechanism of the preferential oxidation of carbon monoxide in the presence of hydrogen (PrOx) over an unsupported gold powder (mean particle size ∼20 nm and free of silver) have been investigated using flow fixed bed catalytic testing and diffuse reflectance infrared Fourier transform spectroscopy coupled to mass spectrometry (operando DRIFTS or DRIFTS-MS). It is shown that the presence of H2 has a favourable effect on the oxidation of CO, either by strongly accelerating the reaction or by preventing the catalyst deactivation, depending on the conditions used. Variation of the hydrogen partial pressure has allowed us to determine partial reaction orders for both CO oxidation and H2 oxidation under PrOx conditions. An infrared band at ∼2113 cm−1, corresponding to on-top CO adsorption on metallic gold, has been observed below 150 °C. In addition, adsorbed hydroxyl groups gradually develop simultaneously to gas-phase water in the course of the reaction at increasing temperatures. The promotional effect of hydrogen is ascribed to highly oxidative HxOy intermediates formed from the interaction between H2 and O2 on the gold surface.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Catalysis Today - Volume 138, Issues 1–2, 15 October 2008, Pages 43–49
نویسندگان
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