کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
55714 47063 2011 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Reactivity of NH3 over (Fe)/H-ZSM-5 zeolite: Studies of temperature-programmed and steady-state reactions
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Reactivity of NH3 over (Fe)/H-ZSM-5 zeolite: Studies of temperature-programmed and steady-state reactions
چکیده انگلیسی

The NH3 reactivity was investigated over H-ZSM-5 and iron oxide deposited H-ZSM-5 by temperature-programmed surface interaction (TPSI) of adsorbed NH3 (NH3(ad)) with NO, O2, and “NO + O2”, and by steady-state dynamic reactions consisting of “NH3 + NO”, “NH3 + O2”, and “NH3 + NO + O2” systems. It was found that O2 primarily interacts with NH3(ad) on Brønsted acid sites. NO mainly interacts with NH3(ad) on Lewis acid sites, whereas its interaction with NH3(ad) on Brønsted acid sites results in N2O formation. TPSI provides direct evidence of the “fast” reaction of NO/NO2 with NH3(ad) on Brønsted acid sites in “NO + O2” environment, where O2 concentration plays a critical role. Iron oxide enhances all interactions, particularly those with NH3(ad) on Brønsted acid sites, as witnessed by both TPSI and steady-state reactions. But, iron oxide does not change the activation energy barrier for NH3 conversion, indicating that both acid sites and iron oxide are essential for NH3 SCR of NOx. As a result, a dual mechanism over Lewis and Brønsted acid sites was proposed.

Figure optionsDownload high-quality image (188 K)Download as PowerPoint slideHighlights
► Temperature-programmed surface interaction (TPSI) was used to study the interactions of adsorbed NH3 with NO, O2, and “NO + O2”.
► NH3 adsorbed on Lewis and Brønsted acid sites interacts primarily with NO and O2, respectively. Dispersed iron oxide accelerates all interaction rates, but does not change the activation energy barrier for steady-state NH3 conversion.
► TPSI provides direct evidence of the “fast” reaction of NO/NO2 with NH3(ad) on Brønsted acid sites in “NO + O2” environment, where O2 concentration plays a critical role.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Catalysis Today - Volume 175, Issue 1, 25 October 2011, Pages 2–11
نویسندگان
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