Influence of the V + Mo/Al ratio on vanadium and molybdenum speciation and catalytic properties of V-Mo-ZSM-5 prepared by solid-state reaction

摘要

V-Mo-ZSM-5 catalysts with various composition prepared by solid-state ion exchange were investigated with respect to their physico-chemical characteristics using chemical analysis, XRD, BET, DRIFT, UV-vis, ~(27)AlMAS-NMR spectroscopy, H2 TPR and TPD of NH3. It was found that all the preparations leads to either metal ions sitting at the bridging oxygen of Si-OH-Al or anchored at Si-OH groups or deposited as oxide. These different solids were tested in the selective catalytic reduction of NO_x by ammonia. The main result is that upon addition of small amount of Mo to V-ZSM-5, catalytic performances were enhanced.