کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5356613 | 1503611 | 2015 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Understanding the dispersion of Ag on high surface area TiO2 supports using XPS intensity ratios
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Silver-titania (Ag/TiO2) adsorbents, in the range of 4Â wt% Ag, display high selectivity toward sulfur heterocyclic compounds from complex fuel streams containing other aromatics. An experimental investigation of Ag on TiO2 has been undertaken to understand the state of dispersion and growth of Ag. XPS is one of the more promising characterization tools for the state of dispersion. Silver loading from 1Â wt% to 20Â wt% on 150Â m2/g titania was investigated. Ag/Ti intensity ratios increased linearly with Ag content up to 4Â wt% and increased less significantly thereafter from 8Â wt% to 20Â wt% indicating nucleation and growth of Ag crystallites. Inelastic mean free path (IMFP) calculations were used to estimate Ag crystallite size based on the attenuation of the Ag signal, realizing in this regime there is insufficient Ag to attenuate background titania. At 4, 8, 12, and 20Â wt% the estimated average crystallite sizes were 0.35, 0.71, 0.84, and 1.11Â nm respectively. Ag loadings up to 4Â wt% were present in the form of Ag+1 adatoms presumably occupying TiO2 surface defects. Saturation of surface TiO2 defects is in good agreement with quantitative sulfur heterocycle adsorption.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Surface Science - Volume 353, 30 October 2015, Pages 679-685
Journal: Applied Surface Science - Volume 353, 30 October 2015, Pages 679-685
نویسندگان
Zenda D. Davis, Bruce J. Tatarchuk,