کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
608883 880610 2011 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Textural, structural, and morphological characterizations and catalytic activity of nanosized CeO2–MOx (M = Mg2+, Al3+, Si4+) mixed oxides for CO oxidation
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی شیمی کلوئیدی و سطحی
پیش نمایش صفحه اول مقاله
Textural, structural, and morphological characterizations and catalytic activity of nanosized CeO2–MOx (M = Mg2+, Al3+, Si4+) mixed oxides for CO oxidation
چکیده انگلیسی

The present work focuses on the combination of ceria with another oxide of different ionic valences from period 3 (Mg2+, Al3+, and Si4+) using coprecipitation method, followed by calcination at 450 and 750 °C, respectively. The textural, structural, morphological and redox properties of nanosized ceria–magnesia, ceria–alumina and ceria–silica mixed oxides have been investigated by means of N2 physisorption, XRD, Raman, HRTEM, DRS, FT-IR, and H2-TPR technologies. XRD results of these mixed oxides reveal that only nanocrystalline ceria (ca. 3–6 nm for the 450 °C calcined samples) could be observed. The grain size of ceria increases with the increasing calcination temperature from 450 to 750 °C due to sintering effect. The highest specific surface area is obtained at CeO2–Al2O3 mixed oxides when calcination temperature reaches 750 °C. Raman spectra display the cubic fluorite structure of ceria and the existence of oxygen vacancies, and displacement of oxygen ions from their normal lattice positions in the ceria-based mixed oxides. DRS measurements confirm that the smaller the grain size of the ceria, the higher indirect band gap energy. H2-TPR results suggest that the reductions of surface and bulk oxygen of ceria were predominant at low and high calcination temperature, respectively. Finally, CO oxidation were performed over these ceria-based mixed oxides, and the combination of CeO2–Al2O3 exhibited highest activity irrespective of calcination temperature, which may due to excellent textural/structural properties, good homogeneity, and redox abilities.

The CeO2–Al2O3 mixed oxides exhibited higher CO oxidation activity than corresponding CeO2–MgO and CeO2–SiO2 mixed oxides due to excellent textural/structural properties, good homogeneity, and redox abilities.Figure optionsDownload high-quality image (132 K)Download as PowerPoint slideResearch highlights
► The textural characterizations suggested that alumina could be act as a very effective surface stabilizer for ceria-based mixed oxides.
► The structural characterizations showed the presence of CeO2 nanocrystals and amorphous oxides.
► The reducible features exhibited the reductions of surface and bulk oxygen, which was dependent upon calcination temperature.
► CO oxidation results suggested CeO2−Al2O3 exhibited the highest activity due to excellent textural/structural properties and redox properties.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Colloid and Interface Science - Volume 354, Issue 1, 1 February 2011, Pages 341–352
نویسندگان
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