NOx storage and reduction over copper-based catalysts. Part 2: Ce 0.8 M 0.2 O δ supports (M = Zr, La, Ce, Pr or Nd)

Abstract

Highlights  Stored NOx thermal stability depends on the acidic/basic character of the ceria dopant  Stored NOx thermal stability increases as follows: Zr none Nd Pr La  CuO/Ce0.8La0.2O: Best NOx removal in NSR experiments with CO + H2 pulses  CuO/Ce0.8Zr0.

Depicting the Nitric Oxide (NO) Chemical Sorption in Lithium Cuprate (Li2CuO2), through Thermokinetic and Spectroscopic Analyses

“…In the case of the 1350 cm –1 band, the signal was detected at a higher temperature than in the presence of oxygen, matching with the desorption stage observed during the thermogravimetric tests (Figure ). Furthermore, a different vibration band was recorded at 1240 cm –1 in the same temperature range, which can be associated with the presence of monodentate nitrate considering a slight shift to low wavenumbers . The band located at 835 cm –1 was observed during the desorption stage (300–500 °C), evidencing partial nitrate decomposition.…”

“…Furthermore, a different vibration band was recorded at 1240 cm −1 in the same temperature range, which can be associated with the presence of monodentate nitrate considering a slight shift to low wavenumbers. 45 The band located at 835 cm −1 was observed during the desorption stage (300−500 °C), evidencing partial nitrate decomposition. Finally, the vibration band located at 1378 cm −1 (NO 3 1− ) was not observed, as in the presence of oxygen case.…”

“…First, a linear nitrite signal was observed (1035 cm –1 ) as in the presence of oxygen condition, but at a different temperature range: from 100 to 275 °C. At room temperature (25 °C), a narrow vibration band (1245 cm –1 ) was depicted, suggesting the presence of monodentate nitrates, while the signal at 1435 cm –1 , observed from room temperature to 500 °C, corresponded to absorbed nitro groups M-NO 2 . The summary results from these vibration bands are presented in Table .…”

Construction of cerium-based oxide catalysts with abundant defects/vacancies and their application to catalytic elimination of air pollutants

“…Therefore, the NO x storage capacity was the key to the catalysts exhibiting high NO x conversion. Bueno-López et al 151 investigated the NSR performance of 5% copper catalysts on Ce 0.8 M 0.2 O δ supports (M = Zr, La, Ce, Pr, Nd). In the absence of reductant pulses, NO x was stored on the catalysts as nitrite and nitro groups below 200–250 °C, whereas above this temperature nitrates were the main species identified.…”

Efficient Pt/Ba/SnxCe1–xO2 Catalysts for High-Temperature Lean NOx Traps with High H2O and CO2 Tolerance

“…CeO 2 is a support with higher stability for lean NO x trap than Al 2 O 3 . The NSR activity of CuO/CeO 2 can be enhanced by doping with other cations with improved thermal stability and redox ability . Moreover, it is reported that the addition of SnO 2 can increase the H 2 O tolerance of the catalysts in various reactions, for example, selective catalytic reduction of NO by NH 3 and CO oxidation. − In view of the characteristics of CeO 2 and SnO 2 , Sn–Ce solid solution may act as an efficient support to improve the H 2 O and CO 2 tolerance of the catalysts for HT NSR.…”