کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
75139 49110 2010 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Entropic effects and isosteric heats of nitrogen and carbon dioxide adsorption on chabazite zeolites
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Entropic effects and isosteric heats of nitrogen and carbon dioxide adsorption on chabazite zeolites
چکیده انگلیسی

Equilibrium adsorption isotherms for CO2 and N2 were measured on a fully exchanged potassium chabazite (KCHA) zeolite, and partially exchanged sodium-chabazite (NaCHA) and lithium-chabazite (LiCHA) zeolites. This work presents integral thermodynamic functions and isosteric heats of N2 and CO2 adsorption equilibria on a fully exchanged potassium chabazite (KCHA) zeolite, and compares these to those functions measured on sodium exchanged chabazite (NaCHA) and lithium exchanged chabazite (LiCHA) zeolites. The thermodynamic quantities were calculated from equilibrium isotherms as function of loading. Adsorption of N2 on KCHA was considered with distinct layers in inter-crystal spaces and mesopores volume, while CO2 adsorption in KCHA cavities was more readily interpreted as fluid-like volume filling mechanism. The molecules comprising this fluid (CO2) are in the dispersion energy field of the crystals and of each other, bounded also by considerable field-gradient quadrupole energy. In all cationic forms the adsorption equilibrium loading and differential enthalpies for CO2 were considerably higher than those for N2. The CO2 integral entropy showed a rapid decreasing trend close to the saturation capacity of the cavities, demonstrating an appreciable loss of molecule degrees of freedom. The results of this work provide useful thermodynamic information that help in understanding the adsorption of N2 and CO2 on a fully exchanged KCHA zeolite.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Microporous and Mesoporous Materials - Volume 132, Issues 1–2, July 2010, Pages 22–30
نویسندگان
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