In situ characterization of Cu–Co oxides for catalytic application

2015 ◽  
Vol 177 ◽  
pp. 249-262 ◽  
Author(s):  
Z. Y. Tian ◽  
H. Vieker ◽  
P. Mountapmbeme Kouotou ◽  
A. Beyer
Keyword(s):  
Thermal Properties ◽  
Chemical Vapor ◽  
Functional Materials ◽  
Catalytic Performance ◽  
Structure Property ◽  
Temperature Oxidation ◽  
Spatially Resolved ◽  
Structure Property Relationships ◽  
Potential Applications

In situ emission and absorption FTIR methods were employed to characterize the spatially resolved structure of binary Co–Cu oxides for low-temperature oxidation of CO and propene. Co–Cu oxide catalysts were controllably synthesized by pulsed-spray evaporation chemical vapor deposition. XRD, FTIR, XPS, UV-vis and helium ion microscopy (HIM) were employed to characterize the as-prepared thin films in terms of structure, composition, optical and thermal properties as well as morphology. In situ emission FTIR spectroscopy indicates that Co3O4, CuCo2O4 and CuO are thermally stable at 650, 655 and 450 °C, respectively. The catalytic tests with absorption FTIR display that the involvement of Co–Cu oxides can initiate CO and C3H6 oxidation at lower temperatures. The results indicate that in situ emission and absorption FTIR are useful techniques to explore the thermal properties and catalytic performance of functional materials, allowing many potential applications in tailoring their temporally and spatially resolved structure-property relationships.

scholarly journals Ambient base-free glycerol oxidation over bimetallic PdFe/SiO2 by in situ generated active oxygen species

2021 ◽  
Author(s):  
Ricci Underhill ◽  
Mark Douthwaite ◽  
Richard J. Lewis ◽  
Peter J. Miedziak ◽  
Robert D. Armstrong ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Bimetallic Catalyst ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Active Oxygen Species ◽  
Catalytic Performance ◽  
Resonance Spectroscopy ◽  
Oxygen Species ◽  
Paramagnetic Resonance ◽  
Temperature Oxidation

AbstractLow temperature oxidation of alcohols over heterogeneous catalysts is exceptionally challenging, particularly under neutral conditions. Herein, we report on an efficient, base-free method to oxidise glycerol over a 0.5%Pd-0.5%Fe/SiO2 catalyst at ambient temperature in the presence of gaseous H2 and O2. The exceptional catalytic performance was attributed to the in situ formation of highly reactive surface-bound oxygenated species, which promote the dehydrogenation on the alcohol. The PdFe bimetallic catalyst was determined to be significantly more active than corresponding monometallic analogues, highlighting the important role both metals have in this oxidative transformation. Fe leaching was confirmed to occur over the course of the reaction but sequestering experiments, involving the addition of bare carbon to the reactions, confirmed that the reaction was predominantly heterogeneous in nature. Investigations with electron paramagnetic resonance spectroscopy suggested that the reactivity in the early stages was mediated by surface-bound reactive oxygen species; no homogeneous radical species were observed in solution. This theory was further evidenced by a direct H2O2 synthesis study, which confirmed that the presence of Fe in the bimetallic catalyst neither improved the synthesis of H2O2 nor promoted its decomposition over the PdFe/SiO2 catalyst.

scholarly journals Probing the structure of framework materials by high pressure and the example of a magnetic, non-porous coordination polymer

2015 ◽  
Vol 71 (3) ◽  
pp. 247-249 ◽  
Author(s):  
Francesca P. A. Fabbiani
Keyword(s):  
High Pressure ◽  
Coordination Polymer ◽  
Coordination Compounds ◽  
Functional Materials ◽  
Research Tool ◽  
Structure Property ◽  
Framework Materials ◽  
Porous Framework ◽  
Structure Property Relationships ◽  
Porous Coordination Polymer

High pressure has become an indispensable research tool in the quest for novel functional materials. High-pressure crystallographic studies on non-porous, framework materials based on coordination compounds are markedly on the rise, enabling the unravelling of structural phenomena and taking us a step closer to the derivation of structure–property relationships.

scholarly journals Carbon-Involved Near-Surface Evolution of Cobalt Catalyst during Reaction: An in-situ Study

2020 ◽  
Author(s):  
Feng Yang ◽  
Haofei Zhao ◽  
Wu Wang ◽  
Qidong Liu ◽  
Xu Liu ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Carbon Diffusion ◽  
Deposition Process ◽  
Catalytic Performance ◽  
Surface Evolution ◽  
Near Surface ◽  
Co Catalysts ◽  
Transmission Electron ◽  
Walled Carbon Nanotubes

Abstract When carbon-containing species are involved in reactions catalyzed by transition metals at high temperature, the diffusion of carbon on/in catalysts dramatically influence the catalytic performance. Acquiring information on the carbon-diffusion-involved evolution of catalysts at atomic level is crucial for understanding the reaction mechanism yet also challenging. For the chemical vapor deposition process of single-walled carbon nanotubes (SWCNTs), we developed methodologies to record in-situ the near-surface structural and chemical evolution of Co catalysts with carbon permeation using an aberration-corrected environmental transmission electron microscope and the synchrotron X-ray absorption spectroscopy. The nucleation and growth of SWCNTs were linked with the partial carbonization of catalysts and the alternating dissolvement-precipitation of carbon in catalysts. The dynamics of carbon atoms in catalysts brings deeper insight into the growth mechanism of SWCNTs and also sheds light on inferring mechanisms of more reactions. The methodologies developed here will find broad applications in studying catalytic and other processes.

Synthesis and structure-property relationships of novel poly(p-xylylene)s with aromatic substituents

e-Polymers ◽  
2001 ◽  
Vol 1 (1) ◽  
Author(s):  
Michael Ishaque ◽  
Ralf Wombacher ◽  
Joachim H. Wendorff ◽  
Andreas Greiner
Keyword(s):  
Chemical Vapor ◽  
Coupling Reaction ◽  
Structure Property ◽  
Ambient Conditions ◽  
Structure Property Relationships ◽  
Aryl Bromides ◽  
Phenyl Rings ◽  
Type Coupling ◽  
Derivatives Of ◽  
Conversion Of Alcohols

AbstractTwo step synthesis of educts for the synthesis of poly(p-xylylene)s was accomplished by Grignard-type coupling reaction of 4-bromotoluene and different aldehydes or p-tolylaldehyde and different aryl bromides followed by conversion of alcohols into corresponding chlorides. Derivatives of poly(p-xylylene) (PPX) were obtained by vapor phase pyrolysis/chemical vapor deposition (CVD) or Gilch-type polymerization of these chlorides. Functional groups along the PPX main chain were introduced by substituted phenyl rings in a-position. The resulting PPXs are soluble under ambient conditions and are amorphous in the solid state. The glass transition temperatures varied only slightly with substituents on the phenyl ring in a-position. Significant enhancement by substituents was found for the thermal stability under nitrogen and a considerable decrease of the surface energies by fluorinated substituents.

scholarly journals Barbituric Acid Based Fluorogens: Synthesis, Aggregation-Induced Emission, and Protein Fibril Detection

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 32 ◽  
Author(s):  
Siyang Ding ◽  
Bicheng Yao ◽  
Louis Schobben ◽  
Yuning Hong
Keyword(s):  
Barbituric Acid ◽  
Fluorescent Dyes ◽  
Photophysical Properties ◽  
Wavelength Region ◽  
Structure Property ◽  
Aggregation Induced Emission ◽  
Long Wavelength ◽  
Structure Property Relationships ◽  
Potential Applications ◽  
Protein Fibril

Fluorescent dyes, especially those emitting in the long wavelength region, are excellent candidates in the area of bioassay and bioimaging. In this work, we report a series of simple organic fluorescent dyes consisting of electron-donating aniline groups and electron-withdrawing barbituric acid groups. These dyes are very easy to construct while emitting strongly in the red region in their solid state. The photophysical properties of these dyes, such as solvatochromism and aggregation-induced emission, are systematically characterized. Afterward, the structure–property relationships of these barbituric acid based fluorogens are discussed. Finally, we demonstrate their potential applications for protein amyloid fibril detection.

Structure-Property Relationships of Poly(Butylene Terephthalate)/Polyolefin Blends

1998 ◽  
Vol 18 (1-2) ◽  
pp. 17-30 ◽  
Author(s):  
D.S. Lee ◽  
J.K. Doo ◽  
B. Kim ◽  
J. Kim
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Structure Property ◽  
Melt Mixing ◽  
Butylene Terephthalate ◽  
Polyolefin Blends ◽  
Structure Property Relationships ◽  
Acrylic Ester ◽  
Discrete Phase

Abstract Structure-property relationships of poly(butylene terephthalate) (PBT) / polyolefin (PO) (80/20) blends modified by a reactive compatibilizer, ethylene-acrylic ester-glycidyl methacrylate terpolymer (BAG), were investigated as part of studies on toughening of PBT. POs used for the study were ethylene propylene rubber (EPR), low-density polyethylene (LDPE), and high-density polyethylene (HDPE), whose deformabilities were different at room temperature. It was observed that the particle size of PO in the discrete phase was the smallest when the EAG content was 8~12 wL%. Shear viscosity of the blends increased as the particle size was decreased. It seems that the morphology and rheological properties of the blends were affected by graft copolymers formed in situ from EAG and PBT during melt mixing. Brittle-tough transition of impact strength of the PBT/EPR/EAG blends was observed when the EAG content was increased from 0 to 4 wt% at room temperature. However, blends of PBT/LDPE/EAG and PBT/HDPE/EAG showed brittle-tough transition with increasing the EAG content from 8 wt% to 12 wt%. It is postulated that toughening of the PBT depends on the deformability of the discrete PO particle as well as its size.

scholarly journals In Situ Monitoring of Growth of Vertically Stacked h-BN/Graphene Heterostructures on Ni Substrates and Their Interface Interaction

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 328-336
Author(s):  
Wei Wei ◽  
Guanhua Zhang ◽  
Jiaqi Pan ◽  
Yi Cui ◽  
Qiang Fu
Keyword(s):  
Hexagonal Boron Nitride ◽  
Chemical Vapor ◽  
In Situ Monitoring ◽  
High Coverage ◽  
Interface Interaction ◽  
Domain Boundaries ◽  
Potential Applications ◽  
Surface Microscopy ◽  
Mechanical Devices

Vertically stacked hexagonal boron nitride (h-BN)/graphene heterostructures present potential applications in electronic, photonic, and mechanical devices, and their interface interaction is one of the critical factors that affect the performances. In this work, the vertical h-BN/graphene heterostructures with high coverage are synthesized by chemical vapor deposition (CVD) of h-BN on Ni substrates followed by segregation growth of graphene at the h-BN/Ni interfaces, which are monitored by in situ surface microscopy and surface spectroscopy. We find that h-BN overlayers can be decoupled from Ni substrates by the graphene interlayers. Furthermore, the h-BN domain boundaries exhibit a confinement effect on the graphene interlayer growth and the lower graphene domains are limited within the upper h-BN domains. This work provides new insights into the formation mechanism and interface interaction of the vertical heterostructures.

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