Selective catalytic reduction of nitric oxide with propylene over CuCe-SAPO-34 catalysts under diesel engine exhaust
CuCe-SAPO-44 zeolite catalysts were prepared by incipient wet impregnation method,and their activities of selective catalytic reduction of nitric oxide with propylene(C3H6-SCR)were investigated under lean burning condition.These catalysts were characterized by X-ray diffraction(XRD),N2 adsorption-desorption,UV-vis spectroscopy(UV-Vis),H2 temperature-programmed reduction(H2-TPR)and NH3 temperature-programmed desorption(NH3-TPD).The results had shown that the interaction between the introduced cerium and copper species was beneficial for generating more isolated Cu2+species which improved the low-temperature redox performance of the CuCe-SAPO-34 zeolite catalysts,and thus enhanced the low-temperature SCR activity.There were abundant Lewis acid sites on the skeleton of the bimetallic zeolite catalysts,which were favorable for the adsorption and activation of NOx and C3H6.When Cu∶Ce=4∶2,CuCe-SAPO-34 exhibited the best de-NOx activity with a conversion of NOx more than at 90%when the diesel engine exhaust contained 10%O2 and 5%H2O at 250℃.
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