SCR of NO by NH3 catalyzed by Mo- and V-exchanged zeolite: Effect of Mo precursor salt

摘要

V and Mo exchanged H+-ZSM-5 (Si/Al = 15) zeolite catalysts, prepared by solid-state ion exchange of ammonium metavanadate (2 wt.%) and different molybdenum salt precursors (acetylacetonate, oxide, carbonyl and chloride, molar ratio V/V Mo = 2/3), were tested in the SCR of NO by NH3. Using [CH3COCH=C(O-)CH3](2)MoO2 like-precursor, acetylacetonate ligands extracted Al atoms from the zeolite framework and the formation of Al-2(MoO4)(3) was therefore extended. In the SCR of NO, such an undesired phase as well as crystalline MoO3 inhibited the diffusion of reactants. Starting from MoO3 and Mo(CO)(6) precursors, the formation of small amounts of Al-2(MoO4)(3) is considered. However, the sublimation of Mo(CO)(6) during the solid-state exchange avoided the agglomeration of Al-2(MoO4)(3) and the catalytic performance was therefore improved. The catalyst issued from MoCI3 is highly active in the studied reaction. V2O5 and Mo-V-O species are plausible active sites, while Al-2(MoO4)(3) and MoO3 oxide could be avoided during the exchange of MoCl3 into H+-ZSM-5. (C) 2015 Elsevier Inc. All rights reserved.