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|Title:||SCR of lean NOx with C3H8 over Co/MFI catalysts: Dependence on synthesis condition of MFI and Co location|
Cobalt ion exchange
|Source:||Chen, X.-Y., Shen, S.-C., Chen, H.-H., Kawi, S. (2004-01-01). SCR of lean NOx with C3H8 over Co/MFI catalysts: Dependence on synthesis condition of MFI and Co location. Journal of Catalysis 221 (1) : 137-147. ScholarBank@NUS Repository. https://doi.org/10.1016/j.jcat.2003.07.008|
|Abstract:||The effects of different synthesis conditions for MFI and the different locations of Co2+ on MFI on the catalyst properties for the selective catalytic reduction of NO by C3H8 [C 3H8-SCR] in the presence of excess oxygen were investigated, and the nature of Co2+ was characterized by XRD, FTIR, H2-TPR, XPS, and DTG. H2-TPR shows that the exchanged Co ions in MFI are nonreducible even at 750°C, while the reduction temperature of incorporated Co is at 690°C. Three types of DTG peaks, which correspond to different temperatures for the thermal decomposition or disassociation of TPA, are observed in the differential thermogravimetric (DTG) analysis of the as-synthesized MFI prepared under different conditions, and are related well to C3H8-SCR of NO for three different types of Co sites in MFI: incorporated Co2+ site and two different exchanged Co 2+ sites, respectively. The incorporated Co2+ in MFI with the DTG peak temperature at 418°C is almost inactive for C3H 8-SCR of NO. For the Co2+-exchanged MFI, the sample with a low Co2+-exchange degree has a higher TOF for NO reduction than that having a higher Co2+-exchange degree, indicating that at least two types of Co2+ sites exist in the Co2+-exchanged MFI sample. The corresponding DTG peak temperatures located at 455 and 481°C show two types of exchanged Co ion sites having different surface energies for different activities for SCR of NO, with the Co2+ site with higher surface energy having higher specific catalytic activity for NO reduction. The exchange degree and position of Co2+ depend on the alkalinity of the hydrothermal synthesis condition and the sodium content of the resulting Co 2+-exchanged MFI. © 2003 Elsevier Inc. All rights reserved.|
|Source Title:||Journal of Catalysis|
|Appears in Collections:||Staff Publications|
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