Preparation of the Coupling Co-Precipitation and Impregnation Catalyst Ag/Al₂O₃ with High Catalytic Performance in Selective Catalytic Reduction of NO with C₃H6.

Abstract

This brief paper reported an Ag/Al₂O₃ catalyst of high catalytic performance in C₃H6-SCR (selective catalytic reduction with C₃H6 as the reducer), and demonstrated a new strategy for the preparation of high active Ag/Al₂O₃ catalyst by the coupling co-precipitation and impregnation method. The results show that the coupling co-precipitation and impregnation catalyst was higher active than the usual impregnated catalyst in C₃H6-SCR of NO with broad active temperature window (420-600 °C), and the highest conversions of NO achieved 91% over the coupling co-precipitation and impregnation catalyst at 500 °C. The porous structure parameter, crystal phase structure, surface acidity property and particle morphology of the Ag/Al₂O₃ catalyst were characterized by the Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectra and temperature programmed desorption of ammonia (NH₃-TPD), respectively. Based on the characterization, it is found that the catalyst prepared by the coupling co-precipitation and impregnation method has smaller particles and better dispersion than the usual impregnated catalyst, and so the catalyst exhibited excellent catalytic activity. NH₃-TPD results illustrate that the weak and medium-strong acid sites is conducive to the reactivity of catalyst.