Superior catalytic activity of a Pd catalyst in methane combustion by fine-tuning the phase of ceria-zirconia support

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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Electrical Promotion-Assisted Automotive Exhaust Catalyst: Highly Active and Selective NO Reduction to N2 at Low-Temperatures

10.26434/chemrxiv.14176577 ◽

2021 ◽

Author(s):

Yuki Omori ◽

Ayaka Shigemoto ◽

Kohei Sugihara ◽

Takuma Higo ◽

Toru Uenishi ◽

...

Keyword(s):

Catalytic Activity ◽

Low Temperature ◽

Electric Field ◽

Low Temperatures ◽

No Reduction ◽

Lattice Oxygen ◽

Pd Catalyst ◽

Highly Active ◽

Automotive Exhaust Catalyst ◽

Activated Surface

Pd catalyst (Pd/Ce0.7Zr0.3O2) in an electric field exhibits extremely high three-way catalytic activity (TWC: NO-C3H6-CO-O2-H2O). By applying an electric field to the semiconductor catalyst, low-temperature operation of TWC can be achieved even at 473 K by virtue of the activated surface-lattice oxygen.

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Improvement of Methane Combustion Activity for Pd/ZrO2 Catalyst by Simple Reduction/Reoxidation Treatment

Catalysts ◽

10.3390/catal9100838 ◽

2019 ◽

Vol 9 (10) ◽

pp. 838 ◽

Cited By ~ 1

Author(s):

Chansong Kim ◽

Eunpyo Hong ◽

Chae-Ho Shin

Keyword(s):

Catalytic Activity ◽

Low Temperatures ◽

Methane Combustion ◽

Reduction Temperature ◽

Isothermal Reaction ◽

Ch4 Combustion ◽

Cyclic Temperature ◽

Zro2 Catalyst ◽

Number Of Cycles ◽

Simple Reduction

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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Catalytic Hydrodechlorination of Chlorophenols in a Continuous Flow Pd/CNT-Ni Foam Micro Reactor Using Formic Acid as a Hydrogen Source

Catalysts ◽

10.3390/catal9010077 ◽

2019 ◽

Vol 9 (1) ◽

pp. 77 ◽

Cited By ~ 3

Author(s):

Jun Xiong ◽

Ying Ma

Keyword(s):

Catalytic Activity ◽

Formic Acid ◽

Continuous Flow ◽

Catalyst Surface ◽

Reactor System ◽

Packed Bed Reactor ◽

Pd Catalyst ◽

Ni Foam ◽

Catalytic Hydrodechlorination ◽

Micro Reactor

Catalytic hydrodechlorination (HDC) has been considered as a promising method for the treatment of wastewater containing chlorinated organic pollutants. A continuous flow Pd/carbon nanotube (CNT)-Ni foam micro reactor system was first developed for the rapid and highly efficient HDC with formic acid (FA) as a hydrogen source. This micro reactor system, exhibiting a higher catalytic activity of HDC than the conventional packed bed reactor, reduced the residence time and formic acid consumption significantly. The desired outcomes (dichlorination >99.9%, 4-chlorophenol outlet concentration <0.1 mg/L) can be obtained under a very low FA/substrate molar ratio (5:1) and short reaction cycle (3 min). Field emission scanning electron microcopy (FESEM) and deactivation experiment results indicated that the accumulation of phenol (the main product during the HDC of chlorophenols) on the Pd catalyst surface can be the main factor for the long-term deactivation of the Pd/CNT-Ni foam micro reactor. The catalytic activity deactivation of the micro reactor could be almost completely regenerated by the efficient removal of the absorbed phenol from the Pd catalyst surface.

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An excellent support of Pd catalyst for methane combustion: Thermal-stable Si-doped alumina

Catalysis Today ◽

10.1016/j.cattod.2007.06.011 ◽

2007 ◽

Vol 126 (3-4) ◽

pp. 369-374 ◽

Cited By ~ 30

Author(s):

Xiaohong Wang ◽

Yun Guo ◽

Guanzhong Lu ◽

Yu Hu ◽

Liangzhu Jiang ◽

...

Keyword(s):

Methane Combustion ◽

Pd Catalyst ◽

Si Doped ◽

Thermal Stable

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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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