Catalytic activity of PdO/ZrO2 catalyst for methane combustion

The improvement of methane combustion activity was observed in cyclic temperature-programed and isothermal reactions over Pd/ZrO2 catalysts by simple reduction/reoxidation treatment. The catalytic activity increased during the initial stages of isothermal reaction, and the light-off temperature was lowered as the number of cycles increased in the cyclic temperature-programed reaction. To reveal the origin of activation, variations in the reduction properties after the activation period were carefully investigated through CH4 temperature-programed reduction (TPR) measurements. From the CH4-TPR results, it was confirmed that the reduction temperature decreased significantly after activation. The observation of the CH4-TPR peak at relatively low temperatures is directly proportional to the catalytic activity of CH4 combustion. It was therefore concluded that repeated reduction/reoxidation occurred in the reactant stream, and this phenomenon allowed the combustion reaction to proceed more easily at lower temperatures.

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Improvement of Methane Combustion Activity for Pd/ZrO2 Catalyst by Simple Reduction/Re-oxidation Treatment

10.20944/preprints201909.0250.v1 ◽

2019 ◽

Author(s):

Chansong Kim ◽

Eunpyo Hong ◽

Chae-Ho Shin

Keyword(s):

Catalytic Activity ◽

Methane Combustion ◽

Oxidation Treatment ◽

Ch4 Combustion ◽

Cyclic Temperature ◽

Zro2 Catalyst ◽

Temperature Programmed ◽

Number Of Cycles ◽

Temperature Programmed Reaction ◽

Simple Reduction

The improvement of the methane combustion activity was observed in cyclic temperature-programmed and isothermal reactions over Pd/ZrO2 catalysts by simple reduction/re-oxidation treatment. The catalytic activity increased during the initial stages of isothermal reaction, and the light-off temperature was lowered as the number of cycles increased in the cyclic temperature-programmed reaction. To reveal the origin of activation, variations in the reduction properties after the activation period were carefully investigated through CH4 temperature-programmed reduction (TPR) measurements. From the CH4-TPR results, it was confirmed that the reduction temperature decreased significantly after activation. The observation of the CH4-TPR peak at relatively low temperatures is directly proportional to the catalytic activity of CH4 combustion. It was therefore concluded that repeated reduction/re-oxidation occurred in the reactant stream, and this phenomenon allowed the combustion reaction to proceed more easily at lower temperatures.

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Highly Dispersed Pd Species Supported on CeO2 Catalyst for Lean Methane Combustion: The Effect of the Occurrence State of Surface Pd Species on the Catalytic Activity

Catalysts ◽

10.3390/catal11070772 ◽

2021 ◽

Vol 11 (7) ◽

pp. 772

Author(s):

Yanxiong Liu ◽

Changhua Hu ◽

Longchun Bian

Keyword(s):

Catalytic Activity ◽

Oxygen Vacancies ◽

Methane Combustion ◽

Pd Nanoparticles ◽

High Concentration ◽

Ch4 Combustion ◽

Highly Active ◽

Δ Phase ◽

Occurrence State ◽

Comprehensive Characterization

The correlation between the occurrence state of surface Pd species of Pd/CeO2 for lean CH4 combustion is investigated. Herein, by using a reduction-deposition method, we have synthesized a highly active 0.5% PdO/CeO2-RE catalyst, in which the Pd nanoparticles are evenly dispersed on the CeO2 nanorods CeO2-R. Based on comprehensive characterization, we have revealed that the uniformly dispersed Pd nanoparticles with a particle size distribution of 2.3 ± 0.6 nm are responsible for the generation of PdO and PdxCe1−xO2−δ phase with –Pd2+–O2−–Ce4+– linkage, which can easily provide oxygen vacancies and facilitate the transfer of reactive oxygen species between the CeO2-R and Pd species. As a consequence, the remarkable catalytic activity of 0.5% Pd/CeO2-RE is related to the high concentration of PdO species on the surface of the catalyst and the synergistic interaction between the Pd species and the CeO2 nanorod.

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Performance of Transition Metal Ions Exchanged Zeolite 13X in Greenhouse Gas Reduction

Volume 15: Sustainable Products and Processes ◽

10.1115/imece2007-41360 ◽

2007 ◽

Author(s):

K. S. Hui ◽

Christopher Y. H. Chao ◽

C. W. Kwong ◽

M. P. Wan

Keyword(s):

Activation Energy ◽

Catalytic Activity ◽

Transition Metal ◽

Apparent Activation Energy ◽

Surface Area ◽

Active Sites ◽

Methane Combustion ◽

Bet Surface Area ◽

Metal Loading ◽

Zeolite 13X

This study investigated the performance of multi-transition metal (Cu, Cr, Ni and Co) ions exchanged zeolite 13X catalysts on methane emission abatement, especially at methane level of the exhaust from natural gas fueled vehicles. Catalytic activity of methane combustion using multi-ions exchanged catalyst was studied under different parameters: mole % of metal loading, inlet velocity and inlet methane concentration at atmospheric pressure and 500 °C. Performance of the catalysts was investigated and explained in terms of the apparent activation energy, number of active sites and BET surface area of the catalyst. This study showed that the multi-ions exchanged catalyst outperformed the single-ions exchanged and the acidified 13X catalysts. Lengthening the residence time could also lead to higher methane conversion %. Catalytic activity of the catalysts was influenced by the mole % of metal loading which played important roles in affecting the apparent activation energy of methane combustion, active sites and also the BET surface area of the catalyst. Increasing mole % of metal loading in the catalyst decreased the apparent activation energy for methane combustion and also the BET surface area of the catalyst. In view of these, there existed an optimized mole % of metal loading where the highest catalytic activity was observed.

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