High-Resolution Scanning Electron Microscopy and Microanalysis of Supported Metal Catalysts

1999 ◽  
Vol 589 ◽  
Author(s):  
Jingyue Liu
Keyword(s):  
High Resolution ◽  
Low Voltage ◽  
Supported Catalysts ◽  
Metal Catalysts ◽  
Supported Metal Catalysts ◽  
Surface Sensitivity ◽  
Brightness Field ◽  
Backscattered Electron ◽  
Enhanced Surface ◽  
Supported Metal

AbstractThe use of a high-brightness field emission gun and novel secondary electron detection systems makes it possible to acquire nanometer-resolution surface images of bulk materials, even at low electron beam voltages. The advantages of low-voltage SEM include enhanced surface sensitivity, reduced sample charging on non-conducting materials, and significantly reduced electron range and interaction volume. High-resolution images formed by collecting the backscattered electron signal can give information about the size and spatial distribution of metal nanoparticles in supported catalysts. Low-voltage XEDS can provide compositional information of bulk samples with enhanced surface sensitivity and significantly improved spatial resolution. High-resolution SEM techniques enhance our ability to detect and, subsequently, analyze the composition of nanoparticles in supported metal catalysts. Applications of high-resolution SEM imaging and microanalysis techniques to the study of industrial supported catalysts are discussed.

C-H bond functionalization using Pd and Au supported catalysts with mechanistic insights of the active species

Synthesis ◽  
2021 ◽  
Author(s):  
Tamao Ishida ◽  
Zhenzhong Zhang ◽  
Haruno Murayama ◽  
Eiji Yamamoto ◽  
Makoto Tokunaga
Keyword(s):  
Aromatic Compounds ◽  
Reaction Mechanisms ◽  
Bond Activation ◽  
Supported Catalysts ◽  
Metal Catalysts ◽  
Active Species ◽  
Supported Metal Catalysts ◽  
Bond Functionalization ◽  
Bond Forming ◽  
Supported Metal

The C–H functionalization has been extensively studied as a direct C–C bond forming reaction with high atomic efficiency. The efforts have also been made on the reaction using supported catalysts, which are superior in terms of catalyst separation from the reaction mixture and reusability. In this review, an overview of the C–H functionalization reactions, especially for Pd and Au supported catalysts will be described. In particular, we discuss reaction mechanisms, active species, leaching, reusability, etc. 1 Introduction 2 Types of supported metal catalysts and their active species 3 Modes of C–H bond activation 4 Oxidative C–H C–H coupling of aryl compounds 5 C–H C–H coupling where one side is aromatic 6 C–H acylation of aromatic compounds and related reactions 7 Conclusion

Structure of Supported Metal Catalysts Derived from Molecular Bimetallic Clusters

1987 ◽  
Vol 111 ◽  
Author(s):  
M. J. Kelley ◽  
A. S. Fung ◽  
M. R. McDevitt ◽  
P. A. Tooley ◽  
B. C. Gates
Keyword(s):  
Bimetallic Catalysts ◽  
Hydrogen Reduction ◽  
Supported Catalysts ◽  
Metal Catalysts ◽  
Bimetallic Clusters ◽  
Supported Metal Catalysts ◽  
Gamma Alumina ◽  
Valence States ◽  
Supported Metal

AbstractRe-containing molecular bimetallic clusters were used as precursors for gamma alumina supported catalysts. Characterization by XPS and XAS after hydrogen reduction showed Re valence states in the order Re monometallic > Re-Os bimetallic > Re-Pt bimetallic > zero. These results suggest that industrial bimetallic catalysts are not best understood in terms of alloys, but rather as multifunctional, with each element contributing its own activity.

Studies of Supported Metal Catalysts Using Low Voltage Biased Secondary Electron Imaging in a JSM-6320f Fe-SEM

1997 ◽  
Vol 3 (S2) ◽  
pp. 1223-1224
Author(s):  
J. Liu ◽  
R. L. Ornberg ◽  
J. R. Ebner
Keyword(s):  
Secondary Electron ◽  
Low Voltage ◽  
Supported Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Incident Beam ◽  
Active Species ◽  
Supported Metal Catalysts ◽  
Active Components ◽  
Electron Imaging

Many industrial catalysts have a complex geometric structure to enable reacting gases or fluids to reach as much of the active surface of the catalyst as possible. The catalyzing surface frequently consists of a complex chemical mixture of different phases produced by an evolved chemical process. The active components are often very small particles dispersed on high-surface-area supports. The catalytic properties of this type of catalyst depend on the structure, composition, and morphology of the active species as well as the supports. TEM/STEM and associated techniques have been used extensively to characterize the structure and composition of supported catalysts. Surface morphology of supported catalysts is generally examined by secondary electron imaging, especially at low incident beam energies. It is, however, frequently found that small metal particles are not usually seen in SE images because of the complication of support topography

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