Facilitating role of Pd for hydrogen, oxygen and water adsorption/desorption processes from bulk CeO2 and CeO2/γ-Al2O3

Kaya, Deniz Altay; Singh, Dharamveer; Kıncal, Serkan; Üner, Deniz

doi:10.1016/j.cattod.2018.04.063

Cited by 20 publications

(12 citation statements)

References 32 publications

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“…Indeed, in earlier papers it was already reported that Pd and ceria had a strong influence on the reciprocal redox behavior with palladium promoting low temperature CeO2 reduction and CeO2 promoting Pd oxidation [30,31], a situation confirmed also in more recent works [32][33][34]. The effect of ceria in the promotion of Pd oxidation, as suggested by Farrauto et al [18], has substantial implications for the high temperature methane oxidation activity of Pd-based catalysts and, if in the past this was mainly studied for energy production applications, at present it should be taken into account when considering for example close coupled three-way catalysts for methane abatement.…”

Section: Effect Of Ceria On Pdo Stabilization and Redox Behaviorsupporting

confidence: 55%

Structure-activity relationship in Pd/CeO2 methane oxidation catalysts

Colussi

Fornasiero

Trovarelli

2020

Chinese Journal of Catalysis

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Section: Effect Of Ceria On Pdo Stabilization and Redox Behaviorsupporting

confidence: 55%

Structure-activity relationship in Pd/CeO2 methane oxidation catalysts

Colussi

Fornasiero

Trovarelli

2020

Chinese Journal of Catalysis

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“…However, the 2Pd/CeO 2 -O catalyst exhibits a negative peak at 61 °C due to β-PdH decomposition . The PdO species weakly interacting with the CeO 2 support is reduced to metallic Pd in the hydrogen atmosphere at room temperature, and the formed Pd can further interact with hydrogen to form β-PdH species . This also indicates a lower dispersion of PdO species on the CeO 2 -O support.…”

Section: Resultsmentioning

confidence: 99%

“…78 The PdO species weakly interacting with the CeO 2 support is reduced to metallic Pd in the hydrogen atmosphere at room temperature, and the formed Pd can further interact with hydrogen to form β-PdH species. 79 This also indicates a lower dispersion of PdO species on the CeO 2 -O support. The amount of H 2 released is only 0.03 mmol g cat −1…”

Section: As Summarized Inmentioning

confidence: 95%

Insights into the Influence of CeO₂Crystal Facet on CO₂Hydrogenation to Methanol over Pd/CeO₂Catalysts

et al. 2020

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CeO2 is an excellent potential material for CO2 hydrogenation attributed to the highly tunable properties including metal–support interaction and abundant oxygen vacancy. In this work, four CeO2 supports with structurally well-defined different shapes and crystal facets are hydrothermally prepared, and their effects on the composition of Pd species and oxygen vacancy over Pd/CeO2 catalysts have been intensively investigated in the reduction of CO2 to methanol. The 2Pd/CeO2-R (rods) shows the highest concentration and number of oxygen vacancies, where the (110) facet with high surface oxygen mobility and low oxygen vacancy formation energy is exposed over the CeO2-R surface. The oxygen mobility at the interface of (111) and (100) facets mainly observed on 2Pd/CeO2-P (polyhedrons) is higher than the single (111) and (100) facets mainly observed on 2Pd/CeO2-O (octahedrons) and 2Pd/CeO2-C (cubs), respectively. The presence of Pd highly promotes the formation of oxygen vacancies by providing dissociated H atoms to facilitate the removal of surface O in ceria support under a H2 atmosphere. Both the Pd x Ce1–x Oδ solid solution dominated on CeO2-R and the PdO species dominated on CeO2-O are reduced to metallic Pd after reduction with 6–10 nm average particle size. As revealed by density functional theory (DFT) calculations, in contrast to the single Pd0 atom on CeO2 and the thermodynamically most unstable Pd x Ce1−x Oδ solid solution, the Pd0 nanoparticles are the most stable species under the realistic reaction conditions. The 2Pd/CeO2-R shows the highest catalytic activity as the abundantly available oxygen vacancies function as CO2 adsorption and activation sites. Moreover, oxygen vacancy reactivity is correlated with its formation energy. The lower formation energy facilitates the formation of oxygen vacancy; however, the reactivity of each oxygen vacancy is lower as the TOFoxygen vacancy of 2Pd/CeO2-O is 15 times as that of 2Pd/CeO2-R. Thus, a suitable oxygen vacancy formation energy is likely favorable for enhancing CO2 reactivity. DFT calculations indicate that the CH3OH formation is most probably from the formate (HCOO*) pathway via the C–O bond cleavage in H2COOH*, with the reduction of HCOO* to HCOOH* as the rate-limiting step. These results would provide experimental and theoretical insights into the rational design of an effective catalyst for CO2 hydrogenation.

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“…The negative peak at about 70 °C is attributed to the desorption of H 2 from Pd atoms. The PdO species weakly interacting with support are facile to be reduced into metallic Pd at room temperature, which could interact with H 2 to form β-PdH species. , These β-PdH species could decompose to release H 2 at a higher temperature. The intensity of the negative peak increases with the increase of Pd loading, suggesting that a higher Pd loading with lower dispersion results in more PdO species weakly interacting with support (far from the support surface).…”

Section: Resultsmentioning

confidence: 99%

Acetic Acid Production from CH₄ and CO₂ via Synergistic Catalysis between Pd Particles and Oxygen Vacancies Generated in ZrO₂

Zheng

Shen

et al. 2023

J. Phys. Chem. C

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Co-conversion of CO 2 and CH 4 into acetic acid is of great significance to the environment but is challenged by their chemical stability. Herein, Pd−ZrO 2 catalysts exhibit excellent performance for acetic acid production, which is about 5 times higher than that for pure ZrO 2 . Combined catalytic tests, characterization, and density functional theory (DFT) calculations have revealed a synergistic catalysis mechanism between Pd and H 2 -reduced ZrO 2 , which not only facilitates CO 2 adsorption and activation owing to generating more oxygen vacancies (Ov) but also promotes CH 4 activation owing to resulting largersized metallic Pd particles. DFT calculations demonstrate that the C−C coupling between CH 3 * and COOH* exhibits a lower barrier, which favors acetic acid formation.

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Facilitating role of Pd for hydrogen, oxygen and water adsorption/desorption processes from bulk CeO2 and CeO2/γ-Al2O3

Cited by 20 publications

References 32 publications

Structure-activity relationship in Pd/CeO2 methane oxidation catalysts

Structure-activity relationship in Pd/CeO2 methane oxidation catalysts

Insights into the Influence of CeO₂Crystal Facet on CO₂Hydrogenation to Methanol over Pd/CeO₂Catalysts

Acetic Acid Production from CH₄ and CO₂ via Synergistic Catalysis between Pd Particles and Oxygen Vacancies Generated in ZrO₂

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Facilitating role of Pd for hydrogen, oxygen and water adsorption/desorption processes from bulk CeO2 and CeO2/γ-Al2O3

Cited by 20 publications

References 32 publications

Structure-activity relationship in Pd/CeO2 methane oxidation catalysts

Structure-activity relationship in Pd/CeO2 methane oxidation catalysts

Insights into the Influence of CeO2Crystal Facet on CO2Hydrogenation to Methanol over Pd/CeO2Catalysts

Acetic Acid Production from CH4 and CO2 via Synergistic Catalysis between Pd Particles and Oxygen Vacancies Generated in ZrO2

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Product

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Insights into the Influence of CeO₂Crystal Facet on CO₂Hydrogenation to Methanol over Pd/CeO₂Catalysts

Acetic Acid Production from CH₄ and CO₂ via Synergistic Catalysis between Pd Particles and Oxygen Vacancies Generated in ZrO₂