Effect of oxidized rhodium on oxygen adsorption on cerium oxide

Soria, J.; Martı́nez-Arias, A.; Conesa, J. C.

doi:10.1016/0042-207x(92)90050-7

Cited by 22 publications

(4 citation statements)

References 12 publications

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“…1(a)-(c)] allow one to conclude that the OBC of the Rh/CeO 2 catalyst is not the result of the simple overlap of Rh and CeO 2 buffering capacities, and that a synergetic effect must be invoked to understand its behaviour. This observation is in agreement with the well known existence of singular metal-support interactions for noble metals supported on ceria, 1,[4][5][6][7][8] thus giving credence to the reliability of the experimental technique.…”

supporting

confidence: 89%

Oxygen buffering capacity of mixed cerium terbium oxide: a new material with potential applications in three-way catalysts

Bernal¹,

Blanco²,

Cauqui³

et al. 1997

Chem. Commun.

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supporting

confidence: 89%

Oxygen buffering capacity of mixed cerium terbium oxide: a new material with potential applications in three-way catalysts

Bernal¹,

Blanco²,

Cauqui³

et al. 1997

Chem. Commun.

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“…In a first step, oxygen adsorption occurs as side-on or end-on on ceria sites. Further, end-on adsorption on an oxygen vacancy is shown in eq . , Au impregnation lowers the temperature for both O 2 – formation and oxygen vacancy creation, contributing to the catalytic activity of the material For the DCO region, a similar behavior for the OC zone takes place.…”

Section: Resultsmentioning

confidence: 93%

“…Further, end-on adsorption on an oxygen vacancy is shown in eq 8. 100,101 Au impregnation lowers the temperature for both O 2 − formation and oxygen vacancy creation, contributing to the catalytic activity of the material.…”

Section: Adsorption Experimentsmentioning

confidence: 99%

Effect of Multifunctional Nanocatalysts on n-C₇ Asphaltene Adsorption and Subsequent Oxidation under High-Pressure Conditions

et al. 2020

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This study was carried out to evaluate the effect of high pressure on the oxidation kinetics of n-heptane asphaltenes in the presence and absence of AuPd/Ce0.62Zr0.38O2 catalysts. Bimetallic Au–Pd catalysts with Au/Pd molar ratios from 3.5 to 9.6 were synthesized by deposition–precipitation of Au and followed by incipient wetness impregnation of Pd (3:1AuPd and 10:1AuPd). Adsorption isotherms between hydrocarbons and nanocatalysts were constructed varying the initial asphaltene concentration from 100 to 1500 mg·L–1. Subsequent oxidation was evaluated using thermogravimetric analysis under an air atmosphere, at different pressures from 0.084 to 6.0 MPa in a wide temperature range between 100 and 800 °C. Kinetic parameters were calculated using a first-order kinetic model, considering the system pressure. Adsorption affinity increases in the order support < 3:1AuPd < 10:1AuPd. The catalytic activity of the nanocatalyst was highly dependent on the employed temperature and pressure. Their presence reduces the n-C7 asphaltene decomposition temperature from 450 °C to temperatures below 200 °C for all catalysts used at 6.0 MPa. The main decomposition peaks are presented at 150, 170, and 210 °C for 10:1AuPd, 3:1AuPd, and support, at 6.0 MPa, respectively. Besides, the oxygen chemisorption (OC) region is favored as the material has a greater catalytic activity, increasing from 9.0 to 14.0% (on the load asphaltene basis calculation) for the support and 10:1AuPd catalyst. This was corroborated by the activation energy, which is reduced by more than 30% for all pressures evaluated with the best system. Besides, 89.0 and 80.0% of the mass are lost in the decomposition of the chemisorbed oxygen (DCO) thermal event for the 10:1AuPd and 3:1AuPd nanocatalysts, respectively. Finally, first and second combustions were carried out at temperatures below 240 °C at 6.0 MPa for the 10:1AuPd system, which is a very promising result to determine the reaction pathway for the heavy and extraheavy crude oils during EOR application.

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“…The dissolution of Rh into the bulk ceria was observed after catalyst calcination at 550 °C [24,25]. Meanwhile, Rh + −O−Ce and [Rh−O2] 2− species are likely formed in an oxidative environment [26][27][28][29]. At high temperature, treatment of Rh/CeO2 in air leads to the formation of Rh2O3 [30], slight Rh metal sintering [31,32], and segregation of Rh cations into the CeO2 lattice [33,34].…”

Section: Introductionmentioning

confidence: 99%

Part I: A Comparative Thermal Aging Study on the Regenerability of Rh/Al2O3 and Rh/CexOy-ZrO2 as Model Catalysts for Automotive Three Way Catalysts

et al. 2015

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The rhodium (Rh) component in automotive three way catalysts (TWC) experiences severe thermal deactivation during fuel shutoff, an engine mode (e.g., at downhill coasting) used for enhancing fuel economy. In a subsequent switch to a slightly fuel rich condition, in situ catalyst regeneration is accomplished by reduction with H2 generated through steam reforming catalyzed by Rh 0 sites. The present work reports the effects of the two processes on the activity and properties of 0.5% Rh/Al2O3 and 0.5% Rh/CexOy-ZrO2 (CZO) as model catalysts for Rh-TWC. A very brief introduction of three way catalysts and system considerations is also given. During simulated fuel shutoff, catalyst deactivation is accelerated with increasing aging temperature from 800 °C to 1050 °C. Rh on a CZO support experiences less deactivation and faster regeneration than Rh on Al2O3. Catalyst characterization techniques including BET surface area, CO chemisorption, TPR, and XPS measurements were applied to examine the roles of metal-support interactions in each catalyst system. For Rh/Al2O3, strong metal-support interactions with the formation of stable rhodium aluminate (Rh(AlO2)y) complex dominates in fuel shutoff, leading to more difficult catalyst regeneration. For Rh/CZO, Rh sites were partially oxidized to Rh2O3 and were relatively easy to be reduced to active Rh 0 during regeneration.

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Effect of oxidized rhodium on oxygen adsorption on cerium oxide

Cited by 22 publications

References 12 publications

Oxygen buffering capacity of mixed cerium terbium oxide: a new material with potential applications in three-way catalysts

Oxygen buffering capacity of mixed cerium terbium oxide: a new material with potential applications in three-way catalysts

Effect of Multifunctional Nanocatalysts on n-C₇ Asphaltene Adsorption and Subsequent Oxidation under High-Pressure Conditions

Part I: A Comparative Thermal Aging Study on the Regenerability of Rh/Al2O3 and Rh/CexOy-ZrO2 as Model Catalysts for Automotive Three Way Catalysts

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Effect of oxidized rhodium on oxygen adsorption on cerium oxide

Cited by 22 publications

References 12 publications

Oxygen buffering capacity of mixed cerium terbium oxide: a new material with potential applications in three-way catalysts

Oxygen buffering capacity of mixed cerium terbium oxide: a new material with potential applications in three-way catalysts

Effect of Multifunctional Nanocatalysts on n-C7 Asphaltene Adsorption and Subsequent Oxidation under High-Pressure Conditions

Part I: A Comparative Thermal Aging Study on the Regenerability of Rh/Al2O3 and Rh/CexOy-ZrO2 as Model Catalysts for Automotive Three Way Catalysts

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Effect of Multifunctional Nanocatalysts on n-C₇ Asphaltene Adsorption and Subsequent Oxidation under High-Pressure Conditions