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%).

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.

Design Criteria and Optimization of Heat Recovery Steam Cycles for High-Efficiency, Coal-Fired, Fischer-Tropsch Plants

2012 ◽  
Author(s):  
Emanuele Martelli ◽  
Thomas G. Kreutz ◽  
Manuele Gatti ◽  
Paolo Chiesa ◽  
Stefano Consonni
Keyword(s):  
Heat Recovery ◽  
High Efficiency ◽  
Thermal Power ◽  
Combined Cycle ◽  
Synthesis Process ◽  
Integrated Gasification Combined Cycle ◽  
Fischer Tropsch ◽  
Ft Synthesis ◽  
Optimization Methodology ◽  
Integrated Gasification

In this work, the “HRSC Optimizer”, a recently developed optimization methodology for the design of Heat Recovery Steam Cycles (HRSCs), Steam Generators (HRSGs) and boilers, is applied to the design of steam cycles for three interesting coal fired, gasification based, plants with CO2 capture: a Fischer-Tropsch (FT) synthesis process with high recycle fraction of the unconverted FT gases (CTL-RC-CCS), a FT synthesis process with once-through reactor (CTL-OT-CCS), and an Integrated Gasification Combined Cycle (IGCC-CCS) based on the same technologies. The analysis reveals that designing efficient HRSCs for the IGCC and the once-through FT plant is relatively straightforward, while designing the HRSC for plant CTL-RC-CCS is very challenging because the recoverable thermal power is concentrated at low temperatures (i.e., below 260 °C) and only a small fraction can be used to superheat steam. As a consequence of the improved heat integration, the electric efficiency of the three plants is increased by about 2 percentage points with respect to the solutions previously published.

Improving C11+ Hydrocarbon Product Selectivity by Hydrogen Distribution in Fischer-Tropsch Synthesis

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Shahram Sharifnia ◽  
A. Khodadadi ◽  
Y. Mortazavi
Keyword(s):  
Strong Dependence ◽  
Operating Pressure ◽  
Product Selectivity ◽  
Hydrogen Distribution ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Ft Synthesis ◽  
Co Conversion ◽  
Methane Selectivity ◽  
Hydrocarbon Product

The present study examines the effect of hydrogen distribution (HD) along a Co/SiO2 catalyst bed on Fischer-Tropsch (FT) synthesis. The synthesis is performed under two pressures of 1.0 and 9.0 atm and different H2/CO ratios. The results are compared to those of the usual co-feed, in which both CO and H2 are introduced to the bed inlet. By HD strategy, the methane selectivity is suppressed by as much as 25% and the C11+ selectivity is enhanced up to 26%. CO conversion and product selectivity exhibited a strong dependence on the operating pressure and H2/CO ratio, when hydrogen is distributed.

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...

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.

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