Sintering enhances turn-over frequency of nanoparticles: a case study of FexCy catalyst using reactive MD simulations

2021 ◽  
pp. 151018
Author(s):  
Kuan Lu ◽  
Dan Luo ◽  
Yurong He ◽  
Chun-Fang Huo ◽  
Yuwei Zhou ◽  
...  
Keyword(s):  
Md Simulations ◽  
Turn Over Frequency ◽  
Turn Over

C2 weakens turn over frequency during melting of FexCy: insights from reactive MD simulations

2021 ◽  
Author(s):  
Yubing Liu ◽  
Kuan Lu ◽  
Xingchen Liu ◽  
Jinjia Liu ◽  
Wenping Guo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Melting Process ◽  
Md Simulations ◽  
First Order ◽  
First Order Phase Transition ◽  
Material Behaviors ◽  
Turn Over Frequency ◽  
Turn Over ◽  
First Order Phase

The first-order phase transition plays a pivotal role in material behaviors, yet that of carbides, a type of important materials, has not been systematically studied. Herein, the melting process and...

Facile synthesis of cubical Co3O4 supported Au nanocomposites with high activity for the reduction of 4-nitrophenol to 4-aminophenol

RSC Advances ◽  
2016 ◽  
Vol 6 (39) ◽  
pp. 32430-32433 ◽  
Author(s):  
Yuwen Yang ◽  
Yongyun Mao ◽  
Bin Wang ◽  
Xianwei Meng ◽  
Jiao Han ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
High Activity ◽  
Impregnation Method ◽  
Facile Synthesis ◽  
Turn Over Frequency ◽  
Turn Over

A facile impregnation method has been successfully applied for synthesis of a cubical Co3O4 supported Au nanocomposites, which leads to the excellent catalytic activity for the reduction of 4-nitrophenol with a high turn over frequency of 9.83 min−1.

The Effect of Dicarboxylic Acid Catalyst Structure on Hydrolysis of Cellulose Model Compound D-Cellobiose in Water

2021 ◽  
Vol 08 ◽  
Author(s):  
Harshica Fernando ◽  
Ananda S. Amarasekara
Keyword(s):  
Dicarboxylic Acid ◽  
Model Compound ◽  
Acid Catalyst ◽  
Catalytic Activities ◽  
Polycarboxylic Acids ◽  
Hydrolysis Of Cellulose ◽  
Phthalic Acids ◽  
Turn Over Frequency ◽  
Turn Over ◽  
Hydrolysis Of

Background: Polycarboxylic acids are of interest as simple mimics for cellulase enzyme catalyzed depolymerization of cellulose. In this study, DFT calculations were used to investigate the effect of structure on dicarboxylic acid organo-catalyzed hydrolysis of cellulose model compound D-cellobiose to D-glucose. Methods: Binding energy of the complex formed between D-cellobiose and acid (Ebind), as well as glycosidic oxygen to dicarboxylic acid closest acidic H distance were studied as key parameters affecting the turn over frequency of hydrolysis in water. Result: α-D-cellobiose - dicarboxylic acid catalyst down face approach showed high Ebind values for five of the six acids studied; indicating the favorability of down face approach. Maleic, cis-1,2-cyclohexane dicarboxylic, and phthalic acids with the highest catalytic activities showed glycosidic oxygen to dicarboxylic acid acidic H distances 3.5-3.6 Å in the preferred configuration. Conclusion: The high catalytic activities of these acids may be due to the rigid structure, where acid groups are held in a fixed geometry.

scholarly journals Activation of Cobalt Foil Catalysts for CO Hydrogenation

Catalysts ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 65
Author(s):  
Erling Rytter ◽  
Christian Aaserud ◽  
Anne-Mette Hilmen ◽  
Edvard Bergene ◽  
Anders Holmen
Keyword(s):  
Produced Water ◽  
Co Hydrogenation ◽  
Fischer Tropsch ◽  
Olefin Hydrogenation ◽  
Reduction Time ◽  
Site Density ◽  
Ft Synthesis ◽  
Structure Sensitive ◽  
Turn Over Frequency ◽  
Turn Over

CO hydrogenation has been studied on cobalt foils as model catalysts for Fischer–Tropsch (FT) synthesis. The effect of pretreatment (number of calcinations and different reduction times) for cobalt foil catalysts at 220 °C, 1 bar, and H2/CO = 3 has been studied in a microreactor. The foils were examined by scanning electron microscopy (SEM). It was found that the catalytic activity of the cobalt foil increases with the number of pretreatments. The mechanism is likely an increase in the available cobalt surface area from progressively deeper oxidation of the foil, supported by surface roughness detected by SEM. The highest FT activity was obtained using a reduction time of only 5 min (compared to 1 and 30 min). Prolonged reduction caused the sintering of cobalt crystallites, while too short of a reduction time led to incomplete reduction and small crystallites susceptible to low turn-over frequency from structure sensitivity. Larger crystals from longer reduction times gave increased selectivity to heavier components. The paraffin/olefin ratio increased with the increasing number of pretreatments due to olefin hydrogenation favored by enhanced cobalt site density. From the results, it is suggested that olefin hydrogenation is not structure sensitive, and that mass transfer limitations may occur depending on the pretreatment procedure. Produced water did not influence the results for the low conversions experienced in the present study (<6%).

scholarly journals PENGARUH DEBT TO ASSET RATIO, PERPUTARAN KAS DAN RASIO LANCAR TERHADAP PROFITABILITAS PADA SUB SEKTOR PROPERTY AND REAL ESTATE YANG TERDAFTAR DI BURSA EFEK INDONESIAPERIODE 2014-2016

2018 ◽  
Vol 3 (1) ◽  
pp. 138
Author(s):  
Meilani Ong ◽  
Widya Sari ◽  
Laura Veronica ◽  
Viena Valen Sijabat
Keyword(s):  
Real Estate ◽  
Research Method ◽  
Sampling Method ◽  
Stock Exchange ◽  
Research Result ◽  
Current Ratio ◽  
Financial Reports ◽  
Property Companies ◽  
Turn Over

The purpose of this study is to analize the influence of debt to asset ratio, cash turn over and current ratio on profitability of case study in real estate and property companies listed on indonesia stock exchange from 2014 until 2016.The sample of this study was eighty one  financial  reports which contain twenty seven companies with years of observation for three years by using purposive sampling method.  The  research  method  used  is  descriptive  quantitative  analysis  by using   multiple   regression   analysis.Based   on   the   research   result,   it   can   be   concluded   that   debt to asset ratio,cash turn over and current ratio have no influence toward profitability partially.

scholarly journals Transfer Hydrogenation from 2-propanol to Acetophenone Catalyzed by [RuCl2(η6-arene)P] (P = monophosphine) and [Rh(PP)2]X (PP = diphosphine, X = Cl−, BF4−) Complexes

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 162 ◽  
Author(s):  
Alberto Mannu ◽  
Arnald Grabulosa ◽  
Salvatore Baldino
Keyword(s):  
Transition Metals ◽  
Carbonyl Compounds ◽  
The Other ◽  
Transfer Hydrogenation ◽  
Chiral Alcohols ◽  
High Importance ◽  
Bidentate Phosphine ◽  
Turn Over Frequency ◽  
Turn Over ◽  
Reduction Of Ketones

The reduction of ketones through homogeneous transfer hydrogenation catalyzed by transition metals is one of the most important routes for obtaining alcohols from carbonyl compounds. The interest of this method increases when opportune catalytic precursors are able to perform the transformation in an asymmetric fashion, generating enantiomerically enriched chiral alcohols. This reaction has been extensively studied in terms of catalysts and variety of substrates. A large amount of information about the possible mechanisms is available nowadays, which has been of high importance for the development of systems with excellent outcomes in terms of conversion, enantioselectivity and Turn Over Frequency. On the other side, many mechanistic aspects are still unclear, especially for those catalytic precursors which have shown only moderate performances in transfer hydeogenation. This is the case of neutral [RuCl2(η6-arene)(P)] and cationic [Rh(PP)2]X (X = anion; P and PP = mono- and bidentate phosphine, respectively) complexes. Herein, a summary of the known information about the Transfer Hydrogenation catalyzed by these complexes is provided with a continuous focus on the more relevant mechanistic features.

A Novel Single-Site Catalyst for Olefin Polymerization

2010 ◽  
Vol 657 ◽  
pp. 83-87
Author(s):  
Sriram Venkataramani ◽  
Tharanikkarasu Kannan
Keyword(s):  
Ethylene Polymerization ◽  
Titanium Tetrachloride ◽  
Olefin Polymerization ◽  
Single Site ◽  
Turnover Frequency ◽  
Reaction Conditions ◽  
Co Catalyst ◽  
Infra Red ◽  
Turn Over Frequency ◽  
Turn Over

A novel single-site catalyst was prepared from N-pheneyldiethanolamine and titanium tetrachloride and characterized using spectroscopic methods such as Nuclear Magnetic Resonance (NMR) spectroscopy and Infra Red (IR) spectroscopy. It was prepared insitu and used to polymerize ethylene along with methylaluminoxane (MAO) as co-catalyst. The turnover frequency for ethylene polymerization was found to be 350 g and 550g polymer/mol catalyst/h for 1 bar and at 2 bar respectively. As the turn over frequency at the studied reaction conditions is good, the present N-pheneyldiethanolamine-based catalyst is a good single-site catalyst for olefin polymerization

Size dependence and stochastic nature of yield strength of micron-sized crystals: a case study on Ni 3 Al

2006 ◽  
Vol 462 (2070) ◽  
pp. 1661-1681 ◽  
Author(s):  
A.H.W Ngan ◽  
L Zuo ◽  
P.C Wo
Keyword(s):  
Strong Dependence ◽  
Md Simulations ◽  
Al Alloy ◽  
Dislocation Generation ◽  
Embedded Atom ◽  
Incipient Plasticity ◽  
Material Volume ◽  
General Material ◽  
Atom Potential

Recent experiments indicate that the first yield point of micron-sized metals exhibits significant statistical scatter as well as strong dependence on the specimen size. In this work, molecular dynamics (MD) simulations are carried out to investigate the onset of shear deformation in a small block of material, using an embedded atom potential for the intermetallic Ni 3 Al alloy. Incipient plasticity in the form of homogeneous dislocation generation is observed to occur at atomic sites with interatomic displacements approaching one-half of the Shockley partial Burgers vector. From the distribution function of the interatomic displacements observed in the MD simulations, the probability of a general material volume surviving under given loading conditions is predicted. The survival probability is then calculated for several situations, including homogeneous deformation and nanoindentation, to predict the critical load for incipient plasticity to occur in these situations. The predicted results are compared to micro-pillar compression and nanoindentation experiments on Ni 3 Al available in the literature.

Sign in / Sign up

Export Citation Format

Share Document