scholarly journals Atomic Structure of Pd-, Pt-, and PdPt-Based Catalysts of Total Oxidation of Methane: In Situ EXAFS Study

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1446
Author(s):  
Andrey A. Saraev ◽  
Svetlana A. Yashnik ◽  
Evgeny Yu. Gerasimov ◽  
Anna M. Kremneva ◽  
Zakhar S. Vinokurov ◽  
...  
Keyword(s):  
Shell Structure ◽  
Palladium Catalysts ◽  
Active Component ◽  
Core Shell ◽  
Total Oxidation ◽  
Oxidation Of Methane ◽  
Core Shell Structure ◽  
Bimetallic Palladium ◽  
Palladium Platinum

In this study, 3%Pd/Al2O3, 3%Pt/Al2O3 and bimetallic (1%Pd + 2%Pt)/Al2O3 catalysts were examined in the total oxidation of methane in a temperature range of 150–400 °C. The evolution of the active component under the reaction conditions was studied by transmission electron microscopy and in situ extended X-ray absorption fine structure (EXAFS) spectroscopy. It was found that the platinum and bimetallic palladium-platinum catalysts are more stable against sintering than the palladium catalysts. For all the catalysts, the active component forms a “core-shell” structure in which the metallic core is covered by an oxide shell. The “core-shell” structure for the platinum and bimetallic palladium-platinum catalysts is stable in the temperature range of 150–400 °C. However, in the case of the palladium catalysts the metallic core undergoes the reversible oxidation at temperatures above 300 °C and reduced to the metallic state with the decrease in the reaction temperature. The scheme of the active component evolution during the oxidation of methane is proposed and discussed.

scholarly journals In Situ Synthesis of Core-Shell-Structured SiCp Reinforcements in Aluminium Matrix Composites by Powder Metallurgy

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1201
Author(s):  
Xinghua Ji ◽  
Cheng Zhang ◽  
Shufeng Li
Keyword(s):  
Particle Size ◽  
Powder Metallurgy ◽  
Shell Structure ◽  
Ex Situ ◽  
Aluminium Matrix ◽  
Core Shell ◽  
Matrix Composites ◽  
Aluminium Matrix Composites ◽  
Core Shell Structure

SiCp reinforced aluminium matrix composites (AMCs), which are widely used in the aerospace, automotive, and electronic packaging fields along with others, are usually prepared by ex situ techniques. However, interfacial contamination and poor wettability of the ex situ techniques make further improvement in their comprehensive performance difficult. In this paper, SiCp reinforced AMCs with theoretical volume fractions of 15, 20, and 30% are prepared by powder metallurgy and in situ reaction via an Al-Si-C system. Moreover, a combined method of external addition and an in situ method is used to investigate the synergistic effect of ex situ and in situ SiCp on AMCs. SiC particles can be formed by an indirect reaction: 4Al + 3C → Al4C3 and Al4C3 + 3Si → 3SiC + 4Al. This reaction is mainly through the diffusion of Si, in which Si diffuses around Al4C3 and then reacts with Al4C3 to form SiCp. The in situ SiC particles have a smooth boundary, and the particle size is approximately 1–3 μm. A core-shell structure having good bonding with an aluminium matrix was generated, which consists of an ex situ SiC core and an in situ SiC shell with a thickness of 1–5 μm. The yield strength and ultimate tensile strength of in situ SiCp reinforced AMCs can be significantly increased with a constant ductility by adding 5% ex situ SiCp for Al-28Si-7C. The graphite particle size has a significant effect on the properties of the alloy. A criterion to determine whether Al4C3 is a complete reaction is achieved, and the forming mechanism of the core-shell structure is analysed.

Research of In Situ Polymerization and Core-Shell Structure Modified Emulsified Asphalt

2011 ◽  
Vol 71-78 ◽  
pp. 928-931
Author(s):  
Jin Liang Wu ◽  
Yong Xing Zhang ◽  
Chun Sun Zhang
Keyword(s):  
Shell Structure ◽  
In Situ Polymerization ◽  
Core Shell ◽  
Asphalt Emulsion ◽  
Sound Effect ◽  
Structure And Property ◽  
Modified Asphalt ◽  
Core Shell Structure ◽  
Emulsified Asphalt

Nowadays, there are dominantly two ways of producing modified emulsified asphalt ,one of which is to emulsify modified asphalt, the other to modify asphalt emulsion. But they have the same defect that modifier cannot be evenly mixed with asphalt emulsion, which has side effect on the performance of modified emulsified asphalt. The emulsified asphalt and modifier have different traits in structure and property. In order to make the modifier disperse in asphalt emulsion evenly to improve the performance of modified emulsified asphalt, a tentative idea is brought forward: we shall utilize in-situ polymerization and core-shell structure to enhance feature of emulsified asphalt. Core-shell structure is a method of synthesizing composite material, which can assist to achieve sound effect of the two kinds of materials. The point to emphasize is, in this paper, the introduction and feasibility of the method, its specialty against current mainly methods, the difficulties encountered in practice as well as its promising prospect and the anticipated target to achieve will all be illustrated.

In situ fabricated metal-carbide with core–shell structure for high impact-toughness iron-matrix composite

2019 ◽  
Vol 35 (14) ◽  
pp. 1727-1734
Author(s):  
Lisheng Zhong ◽  
Haiqiang Bai ◽  
Junzhe Wei ◽  
Jianlei Zhu ◽  
Jianhong Peng ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Matrix Composite ◽  
Shell Structure ◽  
High Impact ◽  
Core Shell ◽  
Metal Carbide ◽  
Iron Matrix ◽  
Fabricated Metal ◽  
Core Shell Structure

Novel conductive core–shell particles of elastomeric nanoparticles coated with polypyrrole

RSC Advances ◽  
2015 ◽  
Vol 5 (120) ◽  
pp. 98904-98909 ◽  
Author(s):  
Jiangru Zhang ◽  
Guicun Qi ◽  
Xiang Wang ◽  
Binghai Li ◽  
Zhihai Song ◽  
...  
Keyword(s):  
Shell Structure ◽  
Oxidative Polymerization ◽  
Core Shell ◽  
Conductive Particle ◽  
Core Shell Structure ◽  
Shell Particles ◽  
First Time

For the first time, an ultrafine conductive particle with core–shell structure, acrylonitrile-butadiene elastomeric nanoparticle (NBR-ENP) coated with polypyrrole (PPy), was prepared by in situ oxidative polymerization.

scholarly journals CdS–MoS2 heterostructures on Mo substrates via in situ sulfurization for efficient photoelectrochemical hydrogen generation

RSC Advances ◽  
2017 ◽  
Vol 7 (71) ◽  
pp. 44626-44631 ◽  
Author(s):  
Xianglin Zhu ◽  
Peng Wang ◽  
Qianqian Zhang ◽  
Zeyan Wang ◽  
Yuanyuan Liu ◽  
...  
Keyword(s):  
Shell Structure ◽  
Hydrogen Generation ◽  
Double Layers ◽  
Core Shell ◽  
Core Shell Structure

CdS–MoS2 photoelectrode with a double layers core shell structure was prepared on Mo substrate through using a simple electrodeposition and– in situ sulfurization method on Mo substrate.

In situ design of Cu and Co nanoparticles encapsulated in N-doped graphene with core–shell structure-derived 8-hydroxyquinoline complexes for the selective catalytic reduction of NOx by NH3

2020 ◽  
Vol 44 (29) ◽  
pp. 12639-12645
Author(s):  
Zhifang Li ◽  
Jian Yang ◽  
Xiaoyu Ma ◽  
Jinxing Cui ◽  
Yuanyuan Ma ◽  
...  
Keyword(s):  
Active Site ◽  
Shell Structure ◽  
Catalytic Reduction ◽  
Core Shell ◽  
Excellent Activity ◽  
Doped Graphene ◽  
Reduction Of Nox ◽  
Core Shell Structure ◽  
Co Nanoparticles

The Cu and Co nanoparticles surrounding by N-doped graphene (labeled Cu@N-Gr and Co@N-Gr) catalysts exhibited excellent activity in the NH3-SCR, which is because the graphene shell can effectively prevent the agglomeration of active site.

S-Scheme heterojunction based on in-situ coated core-shell NiCo2S4@WS2 photocatalyst was constructed for efficient photocatalytic hydrogen evolution

2021 ◽  
Author(s):  
Shengming Xu ◽  
Jing Xu ◽  
Linying Hu ◽  
Ye Liu ◽  
Lijun Ma
Keyword(s):  
Hydrothermal Method ◽  
Hydrogen Evolution ◽  
Shell Structure ◽  
Mixed Phase ◽  
Core Shell ◽  
Photocatalytic Hydrogen Evolution ◽  
Core Shell Structure

In this paper, NiCo2S4 was coated on the surface of WS2 of 1T/2H mixed phase by two step hydrothermal method to form a in-situ core-shell structure. The unique S-Scheme heterojunction...

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