Studies on the Catalytic Performance of the Nieuwland Catalyst and Anhydrous Catalyst in the Dimerization of Acetylene to Monovinylacetylene

2012 ◽  
Vol 550-553 ◽  
pp. 312-316 ◽  
Author(s):  
Jian Guo Liu ◽  
Ming Han Han ◽  
Zhan Wen Wang
Keyword(s):  
Crystal Structure ◽  
Electron Density ◽  
Bond Energy ◽  
Catalytic Performance ◽  
Similar Crystal Structure

The present work aimed to find reasons for different catalytic ability of the Nieuwland catalyst and anhydrous catalyst in dimerization of acetylene to produce Monovinylacetylene (MVA). The results showed the catalytic ions in the Nieuwland catalyst and the anhydrous catalyst were CuCl-2 and Cu2Cl-3 respectively by studies on the Cu-containing crystals recovered from corresponding catalyst. CuCl-2 in crystal A and Cu2Cl-3 in crystal B has similar crystal structure, however, Cu(Ι) in Cu2Cl-3 has higher electron density due to stronger bond energy of Cu(Ι)-Cl, which may contribute to the higher activity of the anhydrous catalyst than that of Nieuwland catalyst.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

Optimizing electron density of nickel sulfide electrocatalysts through sulfur vacancy engineering for alkaline hydrogen evolution

2020 ◽  
Vol 8 (35) ◽  
pp. 18207-18214
Author(s):  
Dongbo Jia ◽  
Lili Han ◽  
Ying Li ◽  
Wenjun He ◽  
Caichi Liu ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Electron Density ◽  
Rational Design ◽  
Nickel Sulfide ◽  
Catalytic Performance ◽  
Sulfide Catalysts ◽  
Sulfur Vacancy

A novel, rational design for porous S-vacancy nickel sulfide catalysts with remarkable catalytic performance for alkaline HER.

Crystal structure of acetylxylan esterase from Caldanaerobacter subterraneus subsp. tengcongensis

2021 ◽  
Vol 77 (11) ◽  
Author(s):  
Kohei Sasamoto ◽  
Tomoki Himiyama ◽  
Kunihiko Moriyoshi ◽  
Takashi Ohmoto ◽  
Koichi Uegaki ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Cellulose Acetate ◽  
Electron Density ◽  
Active Site ◽  
Catalytic Domain ◽  
Crystal Packing ◽  
Signal Sequence ◽  
Industrial Applications ◽  
Side Chain ◽  
Active Site Conformation

The acetylxylan esterases (AXEs) classified into carbohydrate esterase family 4 (CE4) are metalloenzymes that catalyze the deacetylation of acetylated carbohydrates. AXE from Caldanaerobacter subterraneus subsp. tengcongensis (TTE0866), which belongs to CE4, is composed of three parts: a signal sequence (residues 1–22), an N-terminal region (NTR; residues 23–135) and a catalytic domain (residues 136–324). TTE0866 catalyzes the deacetylation of highly substituted cellulose acetate and is expected to be useful for industrial applications in the reuse of resources. In this study, the crystal structure of TTE0866 (residues 23–324) was successfully determined. The crystal diffracted to 1.9 Å resolution and belonged to space group I212121. The catalytic domain (residues 136–321) exhibited a (β/α)7-barrel topology. However, electron density was not observed for the NTR (residues 23–135). The crystal packing revealed the presence of an intermolecular space without observable electron density, indicating that the NTR occupies this space without a defined conformation or was truncated during the crystallization process. Although the active-site conformation of TTE0866 was found to be highly similar to those of other CE4 enzymes, the orientation of its Trp264 side chain near the active site was clearly distinct. The unique orientation of the Trp264 side chain formed a different-shaped cavity within TTE0866, which may contribute to its reactivity towards highly substituted cellulose acetate.

Biotransformation, spectroscopic investigation, crystal structure and electrostatic properties of 3,7α-dihydroxyestra-1,3,5(10)-trien-17-one monohydrate studied using transferred electron-density parameters

2018 ◽  
Vol 74 (5) ◽  
pp. 534-541 ◽  
Author(s):  
Ammara Shahid ◽  
Ambreen Aziz ◽  
Sajida Noureen ◽  
Maqsood Ahmed ◽  
Sammer Yousuf ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Electron Density ◽  
Van Der Waals Interactions ◽  
Estradiol Valerate ◽  
Spectrometric Analysis ◽  
Spectroscopic Techniques ◽  
Charge Delocalization ◽  
Atom Model ◽  
Network Of Hydrogen Bonds

The biologically transformed product of estradiol valerate, namely 3,7α-dihydroxyestra-1,3,5(10)-trien-17-one monohydrate, C18H22O3·H2O, has been investigated using UV–Vis, IR, 1H and 13C NMR spectroscopic techniques, as well as by mass spectrometric analysis. Its crystal structure was determined using single-crystal X-ray diffraction based on data collected at 100 K. The structure was refined using the independent atom model (IAM) and the transferred electron-density parameters from the ELMAM2 database. The structure is stabilized by a network of hydrogen bonds and van der Waals interactions. The topology of the hydrogen bonds has been analyzed by the Bader theory of `Atoms in Molecules' framework. The molecular electrostatic potential for the transferred multipolar atom model reveals an asymmetric character of the charge distribution across the molecule due to a substantial charge delocalization within the molecule. The molecular dipole moment was also calculated, which shows that the molecule has a strongly polar character.

scholarly journals Revealing the Activity of Co3Mo3N and Co3Mo3N0.5 as Electrocatalysts for the Hydrogen Evolution Reaction

2022 ◽  
Author(s):  
Youyi Sun ◽  
Lewen Wang ◽  
Olga Guselnikova ◽  
Oleg Semyonov ◽  
James P Fraser ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Catalytic Performance ◽  
Multiple Factors ◽  
Multicomponent Materials

The hydrogen evolution reaction (HER) from water is governed by electrocatalysts used. Multiple factors such as crystal structure, composition and morphology dictate the final catalytic performance. However, as multicomponent materials...

Sign in / Sign up

Export Citation Format

Share Document