Self-oscillations during methane oxidation over Pd/Al 2 O 3 : Variations of Pd oxidation state and their effect on Pd catalytic activity

2016 ◽  
Vol 522 ◽  
pp. 40-44 ◽  
Author(s):  
V.Yu. Bychkov ◽  
Yu.P. Tulenin ◽  
M.M. Slinko ◽  
A.K. Khudorozhkov ◽  
V.I. Bukhtiyarov ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Methane Oxidation ◽  
Oxidation State

scholarly journals Preparation of Pd/SiO2 Catalysts by a Simple Dry Ball-Milling Method for Lean Methane Oxidation and Probe of the State of Active Pd Species

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 725
Author(s):  
Li Yang ◽  
Chao Fan ◽  
Li Luo ◽  
Yanyan Chen ◽  
Zhiwei Wu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Ball Milling ◽  
Methane Oxidation ◽  
Oxidation State ◽  
Catalytic Performance ◽  
The State ◽  
Pd Catalysts ◽  
Tight Contact ◽  
Milling Method

A series of Pd/SiO2 catalysts were prepared with different Pd precursors by a dry ball-milling method and used in the catalytic oxidation of lean methane at low temperature. The effect of Pd precursors on the catalytic performance was investigated and the state of the most active Pd species was probed. The results indicate that dry ball-milling is a simple but rather effective method to prepare the Pd/SiO2 catalysts for lean methane oxidation, and palladium acetylacetonate is an ideal precursor to obtain a highly active Pd/SiO2-Acac catalyst with well- and stably dispersed Pd species, owing to the tight contact between acetylacetonate and Si–OH on the SiO2 support. Besides the size and dispersion of Pd particles, the oxidation state of Pd species also plays a crucial role in determining the catalytic activity of Pd/SiO2 in lean methane oxidation at low temperature. A non-monotonic dependence of the catalytic activity on the Pd oxidation state is observed. The activity of various Pd species follows the order of PdOx >> Pd > PdO; the PdOx/SiO2-Acac catalysts (in particular for PdO0.82/SiO2-Acac when x = 0.82) exhibit much higher activity in lean methane oxidation at low temperature than Pd/SiO2-Acac and PdO/SiO2-Acac. The catalytic activity of PdOx/SiO2 may degrade during the methane oxidation due to the gradual transformation of PdOx to PdO in the oxygen-rich ambiance; however, such degradation is reversible and the activity of a degraded Pd/SiO2 catalyst can be recovered through a redox treatment to regain the PdOx species. This work helps to foster a better understanding of the relationship between the structure and performance of supported Pd catalysts by clarifying the state of active Pd species, which should be beneficial to the design of an active catalyst in lean methane oxidation at low temperature.

Improvement of Catalytic Activity of LaFe0.95Pd0.05O3 for Methane Oxidation under Transient Conditions

2010 ◽  
Vol 115 (4) ◽  
pp. 1231-1239 ◽  
Author(s):  
Arnim Eyssler ◽  
Evgueny Kleymenov ◽  
André Kupferschmid ◽  
Maarten Nachtegaal ◽  
M. Santhosh Kumar ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Methane Oxidation ◽  
Transient Conditions

Controlling the Oxidation State of Pt Single Atoms for Maximizing Catalytic Activity

2020 ◽  
Vol 59 (46) ◽  
pp. 20691-20696 ◽  
Author(s):  
Hojin Jeong ◽  
Dongjae Shin ◽  
Beom‐Sik Kim ◽  
Junemin Bae ◽  
Sangyong Shin ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Oxidation State ◽  
Single Atoms

CATALYTIC ACTIVITY FOR METHANE OXIDATION OF GOETHITE SUPPORTED ON ALUMINA

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4249-4254 ◽  
Author(s):  
KEI-ICHIRO MURAI ◽  
KOHEI TOMITA ◽  
SUGURU TOJO ◽  
TOSHIHIRO MORIGA ◽  
ICHIRO NAKABAYASHI
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Methane Oxidation ◽  
Model Experiment ◽  
The Other ◽  
Catalytic Activities ◽  
Surface Areas ◽  
Oxidation Of Methane ◽  
Other Hand ◽  
Specific Surface Areas

Two kinds of α- Fe 2 O 3 catalysts supported on χ- Al 2 O 3 and γ- Al 2 O 3 were synthesized. α- Fe 2 O 3 was prepared from α- FeOOH . As a model experiment, an investigation was made with the oxidation of methane. As all catalysts with various Fe contents supported on χ- Al 2 O 3 with various Fe contents had higher specific surface areas than those supported on γ- Al 2 O 3, α- Fe 2 O 3/χ- Al 2 O 3 catalyst has higher catalytic activities than α- Fe 2 O 3/γ- Al 2 O 3 catalyst. From SEM-EDS analyses, it is concluded that in α- Fe 2 O 3/χ- Al 2 O 3 catalyst, α- Fe 2 O 3 exists mainly on the surface of the support, because of flatness of the surface of χ- Al 2 O 3. On the other hand, in the case of α- Fe 2 O 3/γ- Al 2 O 3 catalyst, as the surface of support, γ- Al 2 O 3, is uneven, α- Fe 2 O 3 do not partially exist on the surface but in the pores.

Catalytic activity of oxide-supported Pd catalysts on a honeycomb for low-temperature methane oxidation

2003 ◽  
Vol 239 (1-2) ◽  
pp. 169-179 ◽  
Author(s):  
Ryuji Kikuchi ◽  
Shingo Maeda ◽  
Kazunari Sasaki ◽  
Stefan Wennerström ◽  
Yasushi Ozawa ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Methane Oxidation ◽  
Pd Catalysts ◽  
Supported Pd Catalysts ◽  
Supported Pd

Highly active water oxidation on nanostructured biomimetic calcium manganese oxide catalysts

2016 ◽  
Vol 4 (17) ◽  
pp. 6585-6594 ◽  
Author(s):  
Feng Rong ◽  
Jiao Zhao ◽  
Zheng Chen ◽  
Yuxing Xu ◽  
Yaopeng Zhao ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Manganese Oxide ◽  
Oxidation State ◽  
Water Oxidation ◽  
Oxide Catalysts ◽  
Structural Distortion ◽  
Manganese Oxide Catalysts ◽  
Highly Active

Nanostructured biomimetic birnessite CaxMnOy oxides with an intermediate Mn oxidation state and proper structural distortion show improved catalytic activity for the WOR.

scholarly journals Bimetallic Cooperativity with a 2-Phosphinoimidazole-Derived Pd(II) Dimer Enables Naphthalene Synthesis via dimeric Pd(III) Catalysis

2020 ◽  
Author(s):  
Chloe C. Ence ◽  
S. Hadi Nazari ◽  
Mariur Rodriguez Moreno ◽  
Manase F. Matu ◽  
Samantha G. Kulka ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Dft Calculations ◽  
Oxidation State ◽  
Methyl Ketone ◽  
Methyl Ketones ◽  
Mechanistic Studies ◽  
High Oxidation State ◽  
Pd Catalysts ◽  
Silver Triflate ◽  
High Oxidation

We report the synthesis of bimetallic Pd(I) and Pd(II) complexes scaffolded on bidentate 2-phosphinoimidazole ligands. These complexes display unique catalytic activity and enable the expeditious formation of 1,3-disubstituted naphthalenes via an unprecedented coupling of aryl iodides and methyl ketones in the presence of silver triflate. Excellent substrate scope for naphthalene formation is also demonstrated. Mechanistic studies suggest that the transformation proceeds via Pd-catalyzed arylation of a methyl ketone, followed by cyclization with a second equivalent of ketone. Importantly, this ketone arylation processes occurs under oxidizing conditions, suggesting involvement of higher oxidation state dimeric Pd catalysts. Based on experiments and DFT calculations, we propose a mechanism involving high oxidation state Pd(III) bimetallic catalysis. These new bimetallic complexes possess reactivity that is not seen with monometallic Pd catalysts and we confirm the importance of the palladium catalyst for both arylation and cyclization for naphthalene formation.

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