کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5425049 | 1395846 | 2007 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Oxidation enthalpies for reduction of ceria surfaces
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The thermodynamic properties of surface ceria were investigated through equilibrium isotherms determined by flow titration and coulometric titration measurements on high-surface-area ceria and ceria supported on La-modified alumina (LA). While the surface area of pure ceria was found to be unstable under redox conditions, the extent of reduction at 873Â K and a P(O2) of 1.6Â ÃÂ 10â26Â atm increased with surface area. Because ceria/LA samples were stable, equilibrium isotherms were determined between 873 and 973Â K on a 30-wt% ceria sample. Oxidation enthalpies on ceria/LA were found to vary with the extent of reduction, ranging from â500Â kJ/mol O2 at low extents of reduction to near the bulk value of â760Â kJ/mol O2 at higher extents. To determine whether +3 dopants could affect the oxidation enthalpies for ceria, isotherms were measured for Sm+3-doped ceria (SDC) and Y+3-doped ceria. These dopants were found to remove the phase transition observed in pure ceria below 973Â K but appeared to have minimal effect on the oxidation enthalpies. Implications of these results for catalytic applications of ceria are discussed.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Surface Science - Volume 601, Issue 12, 15 June 2007, Pages 2512-2519
Journal: Surface Science - Volume 601, Issue 12, 15 June 2007, Pages 2512-2519
نویسندگان
Gong Zhou, Parag R. Shah, Tiziano Montini, Paolo Fornasiero, Raymond J. Gorte,