Effect of supports on formation and reduction rate of stored nitrates on NSR catalysts as investigated by in situ FT/IR

Performance Improvement of NO x -Storage BaO/Al2O3 by Using Barium Peroxide as the Precursor of BaO

“…FT-IR spectra suggests that the stored NO x species were predominantly nitrates on the present BaO/ Al 2 O 3 materials, which corroborates the prevailing of disproportionation mechanism during NO 2 adsorption and is also in line with results obtained under similar conditions [23,24]. However, formation of small amount of nitrites was also possible since barium nitrites also exhibit bands at around 1,420 and 1,340 cm -1 [15,25]. NO x -TPD experiment (Fig.…”

“…Prolonging the NO 2 exposure only increased the intensity of these bands. The shape of these bands resembles closely to that reported by Nova et al [23], and could be ascribed to bidentate nitrates (chelating or bridging) (m (N=O) ) and m NO 2 ; asym ð Þ À Á ; and monodentate nitrates m NO 2 ; asym ð Þ À Á ; respectively [14,15,[23][24][25]. The absence of the band at 1,560 cm -1 for BaO-H/Al 2 O 3 -550 might be due to the intensity increase due to nitrates formation was offset by the intensity decrease due to carbonates desorption.…”

The effect of C(s) on the trapping of NOx onto Pt/Ba/Al2O3 catalysts

“…Once the trap is saturated a pulse of hydrocarbons over the material reacts to release NO, regenerate the BaO sorbent material and reduce the NO to N 2 [4][5][6][7][8][9][10]. The first step in this cycle is the oxidation of NO (over Pt) to form NO 2 [11,12].…”

Effect of Pt and Ba content on NO x Storage and Reduction Over Pt/Ba/Al2O3

“…As reported by Dawody et al, CO adsorption/desorption at high temperatures, such as CO-TPD, is not reliable for the measurement of Pt dispersion [13]. Therefore, in order to avoid oxidation of CO to CO 2 followed by adsorption on Ba site as carbonate, the sample cell was soaked in a dry ice/ethanol bath and the adsorption of CO was carried out at 208 K [29].…”

“…Dispersion of Pt was measured by the CO-pulse method reported previously [29]. A catalyst was first treated in a flow of air at 673 K for 15 min followed by purging with He for 15 min, and then reduced in a flow of H 2 at 673 K for 15 min followed by purging with He for 15 min.…”