Selective Catalytic Reduction of NOx by Methane over CoH-MFI and CoH-FER Zeolite Catalysts : Characterization and Catalytic Activity

Content Provider	Semantic Scholar
Author	Resini, Carlo Montanari, T. Tommasini Sannino, Luigi Bagnasco, G. Turco, Mark A. Busca, Guido Bregani, F. Notaro, M. Rocchini,, Gabriele
Copyright Year	2003
Abstract	Introduction The removal of nitrogen oxides from flue gases of thermal power plants is currently carried out with the so-called NH3-SCR technology, i.e. the Selective Catalytic Reduction of NO by ammonia over V2O5-WO3/TiO2 or V2O5-MoO3/TiO2 catalysts. The need of storing ammonia is one of the main drawbacks of this technology when applied to power plants. Additionally, the possibility of formation of ammonium sulphates due to reaction of SO2, oxygen, water and ammonia and the dangerous ammonia slip may also limit the conditions for application of this process. A valid alternative process for denitrification of exhaust gases of power plants (as NO decomposition is not yet applicable) implies the use of methane as the reducing agent. Methane as a reductant is, the preferred choice for NOx removal from flue gases because it is already present in methane-fuelled power plants. Co-containing zeolites, such as Co-MFI and Co-FER, were found to be particularly active in CH4-SCR in the presence of oxygen [1]. In this work Co-exchanged MFI and ferrierite (FER) zeolites obtained from NH4zeolites were studied for CH4-SCR. The study was aimed to obtain information on the nature of active sites, and to investigate on the role of protonic sites. To gain this purpose several characterisation techniques were employed, that can give complementary results, such as FT-IR, UV-Vis diffuse reflectance, XRD, TG-DTA NH3-TPD, TPR. Catalytic tests were performed in a flow laboratory plant with a fixed bed reactor operating at atmospheric pressure. The operation condition were: reacting mixture composition: NO = 1500 ppm, CH4 = 1500 ppm, O2 = 25000 ppm, He balance; T = 523 773K; GHSV = 30000 60000 h. Grain dimensions of the catalysts were 150-212 μm. The analysis of NO, NO2, N2O was performed by a continuous spectrophotometer analyser ABB URAS 14 equipped with a NO2 converter. CH4, N2, CO, CO2 concentrations were measured by a HP 5890 gas chromatograph with a TCD detector and a molecular sieves 5A-Porapak Q double packed column.
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Language	English
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Resource Type	Article