کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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45803 | 46422 | 2013 | 14 صفحه PDF | دانلود رایگان |
Cr exchanged ZSM-5 catalysts (Cr/Al = 1) prepared by solid-state ion exchange were tested in SCR of NO with ammonia. Since CrCl3 precursor sublimates during the solid-state reaction, chromate species were stabilized in the exchange sites of H+-ZSM-5 (Si/Al = 15) and Cr2O3 formation is, therefore, limited. However, using Cr nitrate and NH4+-ZSM-5 (Si/Al = 26) zeolite, massive particles of α-Cr2O3 occupied the catalyst surface. At the contrary, well-dispersed particles of Cr2O3 were detected with H+-ZSM-5 and Cr nitrate precursor. Starting from Cr acetate precursor, agglomerates of amorphous oxide were detected with H+-ZSM-5 like support. In the temperature range 50–300 °C, Cr chloride and Cr nitrate precursors and H+-ZSM-5 led to highly active catalysts, while Cr nitrate and NH4+-ZSM-5 led to a poorly active catalyst. However, catalysts issued from Cr acetate are promising in SCR but inefficient agglomerates of oxide (amorphous or crystalline chromia) could be avoided with NH4+-ZSM-5 like support.
. Cr-ZSM-5 catalysts exhibited promising catalytic properties in SCR of NO with NH3 at low temperatures. Higher catalytic activities of Cr-ZSM-5 catalysts provided from a synergy between two crucial preparation parameters: Si/Al molar ratio and the nature of Cr precursor.Figure optionsDownload as PowerPoint slideHighlights
► Cr-ZSM-5 catalysts (Cr/Al = 1) were tested in SCR of NO with NH3.
► Cr2O3 morphology was elucidated by UV–vis DR spectroscopy (B and μ-parameters).
► Agglomerates of crystalline and amorphous Cr2O3 are inefficient in SCR of NO.
► Poly and/or monochromates, Cr2O3 clusters and Cr oxo-cations are active species.
► Cr-ZSM-5 catalysts, being abandoned, are promising in low-temperature SCR.
Journal: Applied Catalysis B: Environmental - Volumes 134–135, 2 May 2013, Pages 367–380