Influence of ba precursors on NOx storage property of Ba/(Pt/gamma-Al2O3) catalysts

NO, storage-reduction catalysts, Ba/(Pt/gamma-Al2O3), were prepared by the impregnation method using Ba(NO3)(2) and Ba(CH3COO)(2) as the barium precursors. Characterization studies of the catalysts were performed by means of X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reaction desorption, and differential thermal analysis-thermogravimetry. The results indicate that the dispersion threshold of Ba (NO3)(2) is 0.047 g/g (Ba/(Pt/-gamma-Al2O3) mass ratio), which is only about 1/3 of that of Ba(CH3COO)(2). After the calcination treatment, the threshold of barium for the catalyst using Ba(CH3COO)2 as the precursor is larger than that using Ba (NO3)(2) as the precursor. As a result, the Ba/Pt/gamma-Al2O3) catalyst prepared from Ba (CH3COO)(2) has a higher NOx storage capacity than the catalyst prepared from Ba(NO3)(2).