کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10244544 | 47692 | 2005 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Interaction between sulfated zirconia and alkanes: prerequisites for active sites-formation and stability of reaction intermediates
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
کاتالیزور
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چکیده انگلیسی
Two sulfated zirconia catalysts were prepared via sulfation and calcination of zirconium hydroxide at 873 K; the zirconium hydroxide had been aged at room temperature for 1 h (SZ-1) or aged at 373 K for 24 h (SZ-2). SZ-1 was active for n-butane isomerization at 373 K; SZ-2 reached a similar performance level only at 473 K. Both materials contained about 9 wt% sulfate and were tetragonal. Because of a lower BET surface area (105 vs. 148 m2/g) SZ-1 featured a higher sulfate density, and XRD and EXAFS analysis showed larger (ca. 10 nm) and more well ordered crystals than for SZ-2. n-Butane TPD on SZ-1 showed a butene desorption peak at low temperature, whereas no obvious butene desorption was observed with SZ-2, suggesting that SZ-1 has a higher oxidizing power at low temperature than SZ-2. The number of sites capable of dehydrogenation are less than 5 μmol/g, because the differential heats of n-butane adsorption as measured by microcalorimetry were 45-60 kJ/mol for higher coverages, indicating weak and reversible interaction. TAP experiments describe the adsorption and desorption behavior of n-butane at different activity states and are the basis for a simple adsorption model. Reactant pulses and purge experiments show that the active species, presumably formed in an oxidative dehydrogenation step, are stable at the surface under reaction conditions.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Catalysis - Volume 230, Issue 1, 15 February 2005, Pages 214-225
Journal: Journal of Catalysis - Volume 230, Issue 1, 15 February 2005, Pages 214-225
نویسندگان
Xuebing Li, Katsutoshi Nagaoka, Laurent J. Simon, Johannes A. Lercher, Sabine Wrabetz, Friederike C. Jentoft, Cornelia Breitkopf, Silke Matysik, Helmut Papp,