Structure and Reactivity of PdOx/ZrO2Catalysts for Methane Oxidation at Low Temperatures

Fujimoto, Kyoko; Ribeiro, Fabio H.; Ávalos-Borja, M.; Iglesia, Enrique

doi:10.1006/jcat.1998.2178

Cited by 483 publications

(397 citation statements)

References 34 publications

Supporting

Mentioning

346

Contrasting

Unclassified

Order By: Relevance

“…The modified mechanism showed a redox cycle of palladium being set up, in which the palladium was alternatively reduced and reoxidised. Similar conclusions have also been reached by Au-Yeung et al [31] by either inserting 18 O isotope into the PdO/ZrO 2 catalyst or using 18 O 2 in the gas phase, where CD 4 was also used in place of CH 4 . Their results showed that the rate determining step being the activation of the C-H bond, and the activation energies for the oxidation of CH 4 and CD 4 were calculated to be 176 and 180 kJ mol −1 , respectively.…”

Section: Mechanism Over Palladium Oxide and Metal Catalystssupporting

confidence: 72%

“…An alternative way of storing hydrogen could be as hydroxyl groups adsorbed on the surface. Such an intermediate has been proposed by Fujimoto et al [18], where the following reaction steps were postulated:…”

Section: Behaviour Of the Water Signalmentioning

confidence: 98%

“…Fujimoto et al [18] has provided a reaction rate expression for the methane oxidation reaction to form CO 2 and H 2 O over PdO/ZrO 2 catalysts.…”

Section: Mechanism Over Palladium Oxide and Metal Catalystsmentioning

confidence: 99%

“…It was also proposed that the rate determining step was the dissociate adsorption of methane on a site pair consisting of adjacent Pd and PdO species where palladium atom sites were considered to occur wherever there were oxygen vacancies on the PdO x surface. More recently, Muller et al [30] modified this mechanism in light of their experiments with isotopic scrambling using 18 O labelled PdO/ZrO 2 catalysts. The modified mechanism showed a redox cycle of palladium being set up, in which the palladium was alternatively reduced and reoxidised.…”

Section: Mechanism Over Palladium Oxide and Metal Catalystsmentioning

confidence: 99%

See 3 more Smart Citations

Oscillatory behaviour during the oxidation of methane over palladium metal catalysts

Zhang

Lee

Mingos

et al. 2003

Applied Catalysis A: General

View full text Add to dashboard Cite

Oscillatory reactions over palladium foil and wire catalysts during the oxidation of methane have been investigated over a wide range of reaction temperatures and argon/methane/oxygen feed gas compositions. Characterisation of the catalyst has also been carried out using scanning electron microscopy (SEM) techniques, which revealed the presence of a porous surface. This suggested that the metal surface has undergone a change since the reaction commenced, and using X-ray powder diffraction (XRD) techniques the palladium phase was shown to be the dominant phase present. Hysteresis phenomena were observed in the activity of the reaction as the temperature was cycled up and down, showing that the metal surface was continually changing throughout the reaction. The activation energies of the reaction during the high reactivity mode, PdO, and low reactivity mode, Pd, were also calculated. Oscillation rates were observed to depend on the dominant surface. Oscillations were frequent when the high reactivity mode was dominant while the activation energy of this mode was found to be low. When the low reactivity mode was dominant, the oscillations were slower and the activation energy was three times larger. The results obtained imply that the behaviour of the palladium surface, switching back and forth from the reduced state to the oxidised state, is responsible for the oscillatory behaviour seen in this system.

show abstract

Section: Mechanism Over Palladium Oxide and Metal Catalystssupporting

confidence: 72%

Section: Behaviour Of the Water Signalmentioning

confidence: 98%

“…Fujimoto et al [18] has provided a reaction rate expression for the methane oxidation reaction to form CO 2 and H 2 O over PdO/ZrO 2 catalysts.…”

Section: Mechanism Over Palladium Oxide and Metal Catalystsmentioning

confidence: 99%

Section: Mechanism Over Palladium Oxide and Metal Catalystsmentioning

confidence: 99%

See 2 more Smart Citations

Oscillatory behaviour during the oxidation of methane over palladium metal catalysts

Zhang

Lee

Mingos

et al. 2003

Applied Catalysis A: General

View full text Add to dashboard Cite

show abstract

“…However, after switching back to the water-free reaction conditions, the toluene conversion increases immediately and return to the initial value gradually, this indicates that the synthesized catalyst has a high tolerance to moisture. It was proposed that the active Pd sites can be blocked by the water molecules involving a quasiequilibrium adsorption-desorption step [48], as shown below:…”

Section: Catalytic Performance and Stability Of Prepared Catalystsmentioning

confidence: 99%

Nanometric palladium confined in mesoporous silica as efficient catalysts for toluene oxidation at low temperature

He¹,

Zhang²,

Yue³

et al. 2012

Applied Catalysis B: Environmental

View full text Add to dashboard Cite

a b s t r a c tShort column SBA-15 supported Pd mesoporous catalysts with controllable acidity and expanded microporosity were firstly prepared through a simple "two-solvents" approach. The catalytic performances of the synthesized catalysts were evaluated for toluene oxidation. The characterization results reveal that Al atoms prefer to be tetrahedrally coordinated in the framework of the synthesized materials, and the acid sites can significantly promote Pd particle dispersion and metallic Pd oxidation due to their electrophilic characters. The Pd-confined catalysts possess high toluene turnover frequencies and toluene can be totally converted to CO 2 and H 2 O below 210 • C. The oxidation reaction can be suppressed by water vapor due to the formation of inactive Pd-hydroxides, and the synthesized catalyst has a good hydrothermal stability and high tolerance to moisture. Both the specific surface area and the toluene adsorption/desorption property are not the main factors determining the catalytic activity. Overall, the toluene oxidation performance is closely related to the support microporosity and acidity, the Pd dispersion and the CO 2 desorption capability.

show abstract

Catalytic Combustion

Forzatti

Groppi

Cristiani

2008

Handbook of Heterogeneous Catalysis

View full text Add to dashboard Cite

The sections in this article are Introduction Base Concepts and System Requirements Design Approaches Fully Catalytic Combustor Fuel Staging Partial Catalytic Hybrid Combustor Commercialization Status and Perspectives Fuel‐Rich Catalytic Combustion Catalytic Materials Honeycomb Substrate Active Catalyst Layer Pd O ‐Based Catalysts Metal‐Substituted Hexaaluminate ( HA ) Catalysts Rich Combustion Catalysts Modeling of Catalytic Combustors Status and Outlook

show abstract

Structure and Reactivity of PdOx/ZrO2Catalysts for Methane Oxidation at Low Temperatures

Cited by 483 publications

References 34 publications

Oscillatory behaviour during the oxidation of methane over palladium metal catalysts

Oscillatory behaviour during the oxidation of methane over palladium metal catalysts

Nanometric palladium confined in mesoporous silica as efficient catalysts for toluene oxidation at low temperature

Catalytic Combustion

Contact Info

Product

Resources

About