The Role of Ceria in Three-Way Catalysts

Diwell, A.F.; Rajaram, Raj R.; Shaw, Hm; Truex, Timothy J.

doi:10.1016/s0167-2991(08)62975-4

Cited by 177 publications

(74 citation statements)

References 28 publications

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“…Moreover, the high thermal stability of ceria is attractive for reactions which are conducted at high temperatures [2]. Therefore, ceria has been extensively utilized in three-way catalysts [5][6][7] and fuel cells [8,9], as well as investigated for its activity in catalytic reactions such as CO oxidation [10,11], steam reforming [12][13][14][15][16][17], and water gas shift (WGS) [18,19].…”

Section: +mentioning

confidence: 99%

Effect of Microgravity on Synthesis of Nano Ceria

et al. 2015

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Cerium oxide (CeO2) was prepared using a controlled-precipitation method under microgravity at the International Space Station (ISS). For comparison, ceria was also synthesized under normal-gravity conditions (referred as control). The Brunauer-Emmett-Teller (BET) surface area, pore volume and pore size analysis results indicated that the ceria particles grown in space had lower surface area and pore volume compared to the control samples. Furthermore, the space samples had a broader pore size distribution ranging from 30-600 Å, whereas the control samples consisted of pore sizes from 30-50 Å range. Structural information of the ceria particles were obtained using TEM and XRD. Based on the TEM images, it was confirmed that the space samples were predominantly nano-rods, on the other hand, only nano-polyhedra particles were seen in the control ceria samples. The average particle size was larger for ceria samples synthesized in space. XRD results showed higher crystallinity as well as larger mean crystal size for the space samples. The effect of sodium hydroxide concentration on synthesis of ceria was also examined using 1 M and 3 M solutions. It was found that the control samples, prepared in 1 M and 3 M sodium hydroxide solutions, did not show a significant difference between the two. However, when the ceria samples were prepared OPEN ACCESSCatalysts 2015, 5 1307 in a more basic medium (3 M) under microgravity, a decrease in the particle size of the nano-rods and appearances of nano-polyhedra and spheres were observed.

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Section: +mentioning

confidence: 99%

Effect of Microgravity on Synthesis of Nano Ceria

et al. 2015

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“…2c). It has been reported that ceria-based oxide stabilized precious metal dispersion and a Pt-ceria complex was formed under oxidizing atmosphere [12][13][14][15]. Figure 3 illustrates the sintering suppression mechanism of Pt supported on ceria based oxide.…”

Section: Sintering Suppression and Its Mechanismmentioning

confidence: 99%

Suppression of Noble Metal Sintering Based on the Support Anchoring Effect and its Application in Automotive Three-Way Catalysis

et al. 2009

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Suppression of noble metal sintering is a very important approach in the development of automotive three-way catalysts. The investigation into the Pt sintering behavior revealed that the formed Pt-O-M (M: cation of oxide, i.e., cerium oxide) bond acted as an anchor to suppress the Pt sintering, and that the strength of the Pt-oxidesupport interaction was well correlated with the electron density of oxygen in the support oxide. To achieve a good balance between catalytic activity and the sintering suppression, ceria based oxide support was verified to be suitable for Pt, and zirconia based oxide support was appropriate support for Rh. Through optimizing the configuration of Pt and Rh in the catalyst, a novel three-way catalyst was developed successfully, and this catalytic activity is far superior to the conventional catalyst, but with lower noble metal content.

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“…Ceria can act as a support material and is particularly effective at stabilizing high Pt dispersions [3], in addition to BaO [4]. Moreover, ceria is able to store NOx at low to moderate temperatures [5][6][7][8][9][10], thereby improving NSR NOx storage capacity.…”

Section: Introductionmentioning

confidence: 99%

Pt/Ce Pr1−O2 (x= 1 or 0.9) NO storage–reduction (NSR) catalysts

Rico-Pérez

Bueno‐López

Kim

et al. 2015

Applied Catalysis B: Environmental

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Model Pt/Ce0.9Pr0.1O2 and Pt/CeO2 NOx storage-reduction catalysts were prepared via nitrate calcination, co-precipitation and carbon-templating routes.Raman spectroscopic data obtained on the catalysts indicated that the introduction of praseodymium into the ceria lattice increased the concentration of defect sites (vacancies), arising from the higher reducibility of the Pr 4+ cation compared to Ce 4+ . For the Pr-promoted samples, H2-TPR profiles contained high temperature bulk reduction peaks which were less pronounced compared with their ceria analogs, indicating that the presence of praseodymium enhances oxygen mobility due to the creation of lattice defects. Under lean-rich cycling conditions, the cycle-averaged NOx conversion of the Pt/Ce0.9Pr0.1O2samples was in each case substantially higher than that of the Pt/CeO2 analog, amounting to a difference of 10-15% in the absolute NOx conversion in some cases. According to DRIFTS data, a double role can be assigned to Pr doping; on the one hand, Pr accelerates the oxidation of adsorbed NOx species during the lean periods. On the other hand, Pr doping destabilizes the adsorbed NOx species during the rich periods, and the kinetics of nitrate decomposition are faster on Pt/Ce0.9Pr0.1O2, leading to improved catalyst regeneration. These results suggest that ceria-based mixed oxides incorporating Pr are promising materials for NOx storage-reduction catalysts intended for low temperature operation.

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The Role of Ceria in Three-Way Catalysts

Cited by 177 publications

References 28 publications

Effect of Microgravity on Synthesis of Nano Ceria

Effect of Microgravity on Synthesis of Nano Ceria

Suppression of Noble Metal Sintering Based on the Support Anchoring Effect and its Application in Automotive Three-Way Catalysis

Pt/Ce Pr1−O2 (x= 1 or 0.9) NO storage–reduction (NSR) catalysts

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