Synergistically Catalytic Removal of HC and NOx from Marine Engine Using Ag/Al2O3
Nitrogen oxide(NOx)and hydrocarbon(HC)emitted from marine engines have large impact on the en-vironment.Directly using HC as a reductant to selective catalytic reduction reaction with NOx(HC-SCR)under the effect of catalyst is a future promising technology for synergistically catalytic removal of NOx and HC.The catalyst with high performance plays a crucial role in HC-SCR process.A supported Ag/Al2O3 catalyst with the commercialγ-Al2O3 as support and AgNO3 as precursor was prepared by wet impregnation method in this research.Fixed bed activity test results indicate that the pure γ-Al2O3 support exhibits catalytic activity for CH4-SCR and C3H8-SCR,and low-temperature catalytic performance is significantly promoted by the Ag addition.Through the characteriza-tion methods of X-ray diffraction(XRD),ultraviolet and visible spectrophotometry(UV-Vis),HC catalytic oxida-tion,NOx temperature programed desorption(NO-O2-TPD)and in situ diffuse reflectance infrared Fourier trans-form spectroscopy(in situ DRIFTS),the supported Ag species state and HC-SCR reaction process were investi-gated in detail.It is found that HC partially oxidizes into acetate promoted by Ag species.NO is activated by catalyst support into monodentate nitrate on the catalyst.The acetate reacts with monodentate and generates N2 and H2O.
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