skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Pt/Ce x Pr 1−x O 2 ( x = 1 or 0.9) NO x storage–reduction (NSR) catalysts

; ; ; ;
Publication Date:
Sponsoring Org.:
OSTI Identifier:
Grant/Contract Number:
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Applied Catalysis. B, Environmental
Additional Journal Information:
Journal Volume: 163; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-05-30 15:34:23; Journal ID: ISSN 0926-3373
Country of Publication:

Citation Formats

Rico-Pérez, Verónica, Bueno-López, Agustín, Kim, Dae Jung, Ji, Yaying, and Crocker, Mark. Pt/Ce x Pr 1−x O 2 ( x = 1 or 0.9) NO x storage–reduction (NSR) catalysts. Netherlands: N. p., 2015. Web. doi:10.1016/j.apcatb.2014.08.016.
Rico-Pérez, Verónica, Bueno-López, Agustín, Kim, Dae Jung, Ji, Yaying, & Crocker, Mark. Pt/Ce x Pr 1−x O 2 ( x = 1 or 0.9) NO x storage–reduction (NSR) catalysts. Netherlands. doi:10.1016/j.apcatb.2014.08.016.
Rico-Pérez, Verónica, Bueno-López, Agustín, Kim, Dae Jung, Ji, Yaying, and Crocker, Mark. 2015. "Pt/Ce x Pr 1−x O 2 ( x = 1 or 0.9) NO x storage–reduction (NSR) catalysts". Netherlands. doi:10.1016/j.apcatb.2014.08.016.
title = {Pt/Ce x Pr 1−x O 2 ( x = 1 or 0.9) NO x storage–reduction (NSR) catalysts},
author = {Rico-Pérez, Verónica and Bueno-López, Agustín and Kim, Dae Jung and Ji, Yaying and Crocker, Mark},
abstractNote = {},
doi = {10.1016/j.apcatb.2014.08.016},
journal = {Applied Catalysis. B, Environmental},
number = C,
volume = 163,
place = {Netherlands},
year = 2015,
month = 2

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.apcatb.2014.08.016

Citation Metrics:
Cited by: 5works
Citation information provided by
Web of Science

Save / Share:
  • We have investigated nitrate formation and decomposition processes, and measured NOx storage performance on Pt-K2O/Al2O3 catalysts as a function of potassium loading. After NO2 adsorption at room temperature, ionic and bidentate nitrates were observed by fourier transform infra-red (FTIR) spectroscopy. The ratio of the former to the latter species increased with increasing potassium loading up to 10 wt%, and then stayed almost constant with additional K, demonstrating a clear dependence of loading on the morphology of the K species. Although both K2O(10)/Al2O3 and K2O(20)/Al2O3 samples have similar nitrate species after NO2 adsorption, the latter has more thermally stable nitrate speciesmore » as evidenced by FTIR and NO2 temperature programmed desorption (TPD) results. With regard to NOx storage performance, the temperature of maximum NOx uptake (Tmax) is 573 K up to a potassium loading of 10 wt%. As the potassium loading increases from 10 wt% to 20 wt%, Tmax shifted from 573 K to 723 K. Moreover, the amount of NO uptake (38 cm3 NOx/g catal) at Tmax increased more than three times, indicating that efficiency of K in storing NOx is enhanced significantly at higher temperature, in good agreement with the NO2 TPD and FTIR results. Thus, a combination of characterization and NOx storage performance results demonstrates an unexpected effect of potassium loading on nitrate formation and decomposition processes; results important for developing Pt-K2O/Al2O3 for potential applications as high temperature NOx storage-reduction catalysts.« less
  • The effect of thermal treatment on the structure and chemical properties of Ba-oxide-based NOx storage/reduction catalysts with different Ba loadings was investigated using BET, TEM, EDS, TPD and FTIR techniques. On the basis of the present and previously reported results, we propose that moderate (< ~873 K) temperature calcinations result in a single monolayer (ML) ‘coating’ of BaO on the alumina surface. At high Ba loading in excess of that required for a full monolayer ‘coating’ (> 8 wt.% BaO), small (~5 nm) particles of ‘bulk’ BaO are present on top of the 1 ML BaO/Al2O3 surface. We did notmore » observe any detectable morphological changes upon higher temperature thermal treatment of 2 and 8 wt% BaO/Al2O3 samples, while dramatic changes occurred for the 20 wt% sample. In this latter case, the transformations included BaAl2O4 formation at the expense of the bulk BaO phase. In particular, we conclude that the surface (ML) BaO phase is quite stable against thermal treatment, while the bulk phase provides the source of Ba for BaAl2O4 formation.« less
  • The effect of La2O3-stabilized ceria incorporation on the functioning of fully formulated lean NOx trap catalysts was investigated. Monolithic catalysts were prepared, corresponding to loadings of 0, 50 and 100 g CeO2/L, together with a catalyst containing 100 g/L of ceria-zirconia (Ce0.7Zr0.3O2). Loadings of the other main components (Pt, Rh and BaO) were held constant. Catalyst evaluation was performed on a bench flow reactor under simulated diesel exhaust conditions, employing NOx storage/reduction cycles. NOx storage efficiency in the temperature range 150-350 C was observed to increase with ceria loading, resulting in higher NOx conversion levels. At 150 C, high richmore » phase NOx slip was observed for all of the catalysts, resulting from an imbalance in the rates of nitrate decomposition and NOx reduction. Optimal NOx conversion was obtained in the range 250-350 C for all the catalysts, while at 450 C high rich phase NOx slip from the most highly loaded ceria-containing catalyst resulted in lower NOx conversion than for the ceria-free formulation. N2O was the major NOx reduction product at 150 C over all of the catalysts, although low NOx conversion levels limited the N2O yield. At higher temperatures N2 was the main product of NOx reduction, although NH3 formation was also observed. Selectivity to NH3 decreased with increasing ceria loading, indicating that NH3 is consumed by reaction with stored oxygen in the rear of the catalyst.« less
  • NO{sub x} storage and reduction on a model Pt/BaO/Al{sub 2}O{sub 3} catalyst was studied by means of in situ DRIFTS measurements. To examine the effect of ceria addition, experiments were also conducted using Pt/BaO/Al{sub 2}O{sub 3} to which Pt/CeO{sub 2} was added as a physical mixture in a 74:26 weight ratio. For the former catalyst, DRIFT spectra acquired during NO/O{sub 2} and NO{sub 2}/O{sub 2} storage indicated the formation of nitrite at 200 C during the initial stages of adsorption, while increasing the adsorption temperature appeared to facilitate the oxidation of nitrite to nitrate. The ceria-containing catalyst afforded similar DRIFTmore » spectra under these conditions, although the presence of cerium nitrates was observed at 200 and 300 C, consistent with NO{sub x} storage on the ceria phase. DRIFT spectra acquired during NO{sub x} reduction in CO and CO/H{sub 2} showed that Ba nitrate species remained on the surface of both catalysts at 450 C, whereas the use of H{sub 2}-only resulted in complete removal of stored NO{sub x}. The observation of Ba carbonates when CO was present suggests that the inferior reduction efficiency of CO may arise from the formation of a crust of BaCO{sub 3} on the Ba phase, which inhibits further NO{sub x} reduction. DRIFT spectra acquired during lean-rich cycling (6.5 min lean, 1.0 min rich) with CO/H{sub 2} as the rich phase reductants revealed that a significant concentration of nitrates remained on the catalysts at the end of the rich phase. This implies that a large fraction of nitrate is not decomposed during cycling and thus cannot participate in NO{sub x} abatement through storage and regeneration.« less