scholarly journals The effect of Mg location on Co-Mg-Ru/γ-Al 2 O 3 Fischer–Tropsch catalysts

2016 ◽  
Vol 374 (2061) ◽  
pp. 20150087 ◽  
Author(s):  
James R. Gallagher ◽  
Paul Boldrin ◽  
Gary B. Combes ◽  
Don Ozkaya ◽  
Dan I. Enache ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
High Resolution ◽  
Oxide Phase ◽  
Fischer Tropsch ◽  
Transmission Electron ◽  
Acid Washing ◽  
Higher Temperature

The effectiveness of Mg as a promoter of Co-Ru/γ-Al 2 O 3 Fischer–Tropsch catalysts depends on how and when the Mg is added. When the Mg is impregnated into the support before the Co and Ru addition, some Mg is incorporated into the support in the form of Mg x Al 2 O 3+ x if the material is calcined at 550°C or 800°C after the impregnation, while the remainder is present as amorphous MgO/MgCO 3 phases. After subsequent Co-Ru impregnation Mg x Co 3− x O 4 is formed which decomposes on reduction, leading to Co(0) particles intimately mixed with Mg, as shown by high-resolution transmission electron microscopy. The process of impregnating Co into an Mg-modified support results in dissolution of the amorphous Mg, and it is this Mg which is then incorporated into Mg x Co 3− x O 4 . Acid washing or higher temperature calcination after Mg impregnation can remove most of this amorphous Mg, resulting in lower values of x in Mg x Co 3− x O 4 . Catalytic testing of these materials reveals that Mg incorporation into the Co oxide phase is severely detrimental to the site-time yield, while Mg incorporation into the support may provide some enhancement of activity at high temperature.

From Nanoparticles to Process: An Aberration-Corrected TEM Study of Fischer-Tropsch Catalysts at Various Steps of the Process

2011 ◽  
Vol 324 ◽  
pp. 197-200 ◽  
Author(s):  
Nadi Braidy ◽  
Carmen Andrei ◽  
Jasmin Blanchard ◽  
Nicolas Abatzoglou
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Amorphous Carbon ◽  
Spherical Aberration ◽  
Fischer Tropsch ◽  
Ft Synthesis ◽  
Transmission Electron ◽  
Treatment Step ◽  
Aberration Corrected

χThe nanostructure of Fischer-Tropsch (FT) Fe carbides are investigated using aberration-corrected high-resolution transmission electron microscopy (TEM). The plasma-generated Fe carbides are analyzed just after synthesis, following reduction via a H2 treatment step and once used as FT catalyst and deactivated. The as-produced nanoparticles (NPs) are seen to be abundantly covered with graphitic and amorphous carbon. Using the extended information limit from the spherical aberration-corrected TEM, the NPs could be indexed as a mixture of NPs in the θ-Fe3C and χ–Fe5C2 phases. The reduction treatment exposed the NPs by removing most of the carbonaceous speSubscript textcies while retaining the χ–Fe5C2. Fe-carbides NPs submitted to conditions typical to FT synthesis develop a Fe3O4 shell which eventually consumes the NPs up to a point where 3-4 nm residual carbide is left at the center of the particle. Subscript textVarious mechanisms explaining the formation of such a microstructure are discussed.

scholarly journals Experimental observation of carousel-like phason flips in the decagonal quasicrystal Al60Cr20Fe10Si10

2021 ◽  
Vol 77 (5) ◽  
Author(s):  
Zhanbing He ◽  
Jean-Luc Maurice ◽  
Haikun Ma ◽  
Yanguo Wang ◽  
Hua Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
High Resolution ◽  
Translational Symmetry ◽  
Long Range Order ◽  
Decagonal Quasicrystal ◽  
Microscopy Imaging ◽  
Transmission Electron

Quasicrystals have special crystal structures with long-range order, but without translational symmetry. Unexpectedly, carousel-like successive flippings of groups of atoms inside the ∼2 nm decagonal structural subunits of the decagonal quasicrystal Al60Cr20Fe10Si10 were directly observed using in situ high-temperature high-resolution transmission electron microscopy imaging. The observed directionally successive phason flips occur mainly clockwise and occasionally anticlockwise. The origin of these directional phason flips is analyzed and discussed.

scholarly journals Grids for Applications in High-Temperature High-Resolution Transmission Electron Microscopy

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Yucheng Lan ◽  
Hui Wang ◽  
Dezhi Wang ◽  
Gang Chen ◽  
Zhifeng Ren
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
High Resolution ◽  
Atomic Layer ◽  
Deposition Technique ◽  
Amorphous Films ◽  
Transmission Electron ◽  
Layer Deposition ◽  
Atomic Layer Deposition Technique

New TEM grids coated with ultrathin amorphous films have been developed using atomic layer deposition technique. The amorphous films can withstand temperatures over in air and in vacuum when the thickness of the film is 2 nm, and up to in air when the thickness is 25 nm, which makes heating TEM grids with nanoparticles up to in air and immediate TEM observation without interrupting the nanoparticles possible. Such coated TEM grids are very much desired for applications in high-temperature high-resolution transmission electron microscopy.

scholarly journals TEM study of boron phosphide: Discovery of rhombohedral BP

2021 ◽  
Author(s):  
Boris Kulnitskiy ◽  
Vladimir Blank ◽  
Tatyana Gordeeva ◽  
Vladimir Mukhanov ◽  
Vladimir Solozhenko
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
High Resolution ◽  
Polymorphic Modification ◽  
Temperature Synthesis ◽  
Boron Phosphide ◽  
High Temperature Synthesis ◽  
Transmission Electron

Microstructure of sphalerite (3C) boron phosphide, BP, produced by self-propagated high-temperature synthesis has been studied by high-resolution transmission electron microscopy. Along with numerous twins on the {111}3C plane, layers of wurtzite (2H) polymorphic modification and previously unknown for BP rhombohedral (3R) structure were found which indicates trimorphism of BP.

scholarly journals A multiscale in situ high temperature high resolution transmission electron microscopy study of ThO2 sintering

Nanoscale ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 7362-7374
Author(s):  
R. Podor ◽  
V. Trillaud ◽  
G. I. Nkou Bouala ◽  
N. Dacheux ◽  
C. Ricolleau ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
High Resolution ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Transmission Electron Microscopy Study ◽  
Transmission Electron ◽  
Initial Stage

Two-grain systems formed by ThO2 nanospheres are used to study the initial stage of sintering up to 1050 °C using HT-HRTEM. The low temperature crystallite rearrangements as well as grain boundary formation and growth are observed.

Process-Induced Deformations and Stacking Faults in 4H-SiC

2006 ◽  
Vol 911 ◽  
Author(s):  
Robert S Okojie ◽  
Xianrong Huang ◽  
Michael Dudley ◽  
Ming Zhang ◽  
Pirouz Pirouz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
High Resolution ◽  
Stress Measurement ◽  
Stacking Faults ◽  
Film Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

AbstractWe used Film Stress Measurement (FSM), Transmission Electron Microscopy (TEM), and High-Resolution X-ray Diffraction (HRXRD) techniques to obtain further knowledge with respect to the deformation, warpage, and stacking faults (SF's) that are induced in n-type 4H-SiC wafers and epilayers when subjected to mechanical polishing and high temperature (1150 oC) processing.

Sign in / Sign up

Export Citation Format

Share Document