Effect of the Incorporation Order of Pt- and Ba-Precursors on the Structure and Catalytic Performance of NSR Catalysts

Abstract

The structural properties and the performance of two NO X storage-reduction (NSR) catalysts prepared as a function of the deposition order of Pt-and Ba-precursors was investigated. The catalyst obtained by incorporating first Ba turned out to be more active mainly due to the larger regeneration extent achieved at temperatures below 350°C. This behaviour was related to the larger external Pt/Ba interface exhibited by this catalyst.

Effects of temperature and rich-phase composition on the performance of a commercial NOx-Storage-Reduction material

“…4). No CO(g) nor 6 any carbonyl species could be observed at anytime at 300C, indicating that essentially all of 7 the CO introduced during the rich phased was converted. 8 In contrast, a large band of CO(g) (showing the P and R branches of the 9 rotovibrational spectrum) were observed both at 100 and 200C.…”

“…A description of the NSR technique 5 and a review of the activity of many materials have been reported elsewhere [3]. The 6 understanding of NSR technology has been hampered by the fact that various (usually non-7 realistic) reaction conditions were often used and a very large number of model materials with 8 varying formulations were investigated [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22]. 9 Several studies have been devoted to commercial NSR materials [23,24,25,26] and in 10 situ FTIR studies [27,28,29,30], but rarely the combination of the two has been reported.…”

“…As far as oxides were concerned, the main 6 constituents were the following, in order of decreasing concentration: Al (ca. 25 ± 5 wt.%), 7 Ce (ca. 15 ± 5 wt.%), Si (ca.…”

“…A computer-controlled automated 6-way valve (Swagelok) 6 was used to switch either the lean or rich feed to the reaction cell in addition to the base feed. 7 The NSR material was typically stabilized over five full cycles before five other cycles were 8 collected to calculate an averaged NSR activity. The NOx conversion is defined by the 9 equation: 10 11 fed NO measured NOx fed NO conversion NOx   (eqn.…”

“…No band 4 decomposition or precise assignment of this region was attempted because of the large 5 number of peaks expected. 6 The variation of the in situ IR spectrum measured over the sample during the lean 7 phase was investigated with a view at understanding NOx adsorption at the three temperatures 8 of interest. The absorbance spectra presented in Fig.…”