Reaction de méthanation du gaz de synthèse: Influence de la température de calcination des catalyseurs à base de nickel

1993 ◽  
Vol 71 (1) ◽  
pp. 107-111
Author(s):  
M. Ghazi ◽  
J. Barrault
Keyword(s):  
Nickel Content ◽  
Great Part ◽  
Extreme Temperature ◽  
Nickel Catalysts ◽  
Economic Situation ◽  
Reaction Conditions ◽  
Methanation Reaction ◽  
Different Temperatures ◽  
Usual Process ◽  
Important Activity

Due to their important activity and selectivity, nickel catalysts are often used to realize the methanation reaction; however, the usual process based on these catalysts is not fitted for the present economic situation. To raise their stability, three catalysts with similar nickel content but calcinated at different temperatures have been studied for the reaction of methanation. The results obtained show that the catalyst calcinated at the highest temperature (973 K) shows the greatest promise because a great part of its activity and of its stability is preserved even when the reaction conditions are extreme (temperature of 773 K).

Kinetics and Mechanism of Oxidation of Aliphatic Secondary Alcohols by Benzimidazolium Fluorochromate in Dimethyl Sulphoxide Solvent

2021 ◽  
Vol 37 (3) ◽  
pp. 626-633
Author(s):  
Bhawana Arora ◽  
Jitendra Ojha ◽  
Pallavi Mishra
Keyword(s):  
Activation Parameters ◽  
Sigmatropic Rearrangement ◽  
Dimethyl Sulphoxide ◽  
Secondary Alcohols ◽  
Hydrogen Ions ◽  
Reaction Conditions ◽  
First Order Kinetics ◽  
Aqueous Solvent ◽  
Ester Formation ◽  
Different Temperatures

Oxidation of secondary alcohols is an important part of synthetic organic chemistry. Various studies are carried out at different reaction conditions to determine the best mechanistic pathways. In our study, oxidation of different secondary alcohols was done by using Benzimidazolium Fluorochromate in Dimethyl Sulphoxide, which is a non-aqueous solvent. Oxidation resulted in the formation of ketonic compounds. The reaction showed first order kinetics both in BIFC and in the alcohols. Hydrogen ions were used to catalyze the reaction. We selected four different temperatures to carry out our study. The correlation within the activation parameters like enthalpies and entropies was in accordance with the Exnerʼs criterion. The deuterated benzhydrol (PhCDOHPh) oxidation exhibited an important primary kinetic isotopic effect (kH / kD = 5.76) at 298 K. The solvent effect was studied using the multiparametric equations of Taft and Swain. There was no effect of addition of acrylonitrile on the oxidation rate. The mechanism involved sigmatropic rearrangement with the transfer of hydrogen ion taking place from alcohol to the oxidant via a cyclic chromate ester formation.

Preliminary Study on the Removal of Hexavalent Chromium in Wastewater with Reduction of Sulfur Dioxide

2013 ◽  
Vol 864-867 ◽  
pp. 1699-1703
Author(s):  
Ji Ming Wu ◽  
Sheng Gao Cheng
Keyword(s):  
Reaction Time ◽  
Sulfur Dioxide ◽  
Hexavalent Chromium ◽  
Reduction Reaction ◽  
High Concentration ◽  
Reaction Conditions ◽  
Ph Values ◽  
Different Temperatures ◽  
Preliminary Study ◽  
High Concentrations

The paper focused on a self-developed methodology through using sulfur dioxide to deal with high concentration of chromium-containing wastewater. It studied the effects of different pH values, different reaction time, different temperatures and different amounts of sulfur with sulfur dioxide reduction reaction on the chromium-containing wastewater. The results showed that: when the reaction conditions were controlled as follows: the pH values ranged from 2 to 4, the reaction temperature was controlled 40~60°C, the amount of sulfur in theoretical was 1.2 times and the reaction time was 40 min, the hexavalent chromium in the high concentrations of chromium-containing wastewater could be effectively removed.

Nanoparticle Growth in Supported Nickel Catalysts during Methanation Reaction-Larger is Better

2014 ◽  
Vol 53 (36) ◽  
pp. 9493-9497 ◽  
Author(s):  
Peter Munnik ◽  
Marjolein E. Z. Velthoen ◽  
Petra E. de Jongh ◽  
Krijn P. de Jong ◽  
Cedric J. Gommes
Keyword(s):  
Nickel Catalysts ◽  
Nanoparticle Growth ◽  
Methanation Reaction ◽  
Supported Nickel Catalysts

scholarly journals The state of BEA zeolite supported nickel catalysts in CO2 methanation reaction

2021 ◽  
pp. 150421
Author(s):  
Wojciech Gac ◽  
Witold Zawadzki ◽  
Grzegorz Słowik ◽  
Marcin Kuśmierz ◽  
Stanislaw Dzwigaj
Keyword(s):  
Nickel Catalysts ◽  
The State ◽  
Co2 Methanation ◽  
Methanation Reaction ◽  
Bea Zeolite ◽  
Supported Nickel Catalysts

Nanoparticle Growth in Supported Nickel Catalysts during Methanation Reaction-Larger is Better

2014 ◽  
Vol 126 (36) ◽  
pp. 9647-9651 ◽  
Author(s):  
Peter Munnik ◽  
Marjolein E. Z. Velthoen ◽  
Petra E. de Jongh ◽  
Krijn P. de Jong ◽  
Cedric J. Gommes
Keyword(s):  
Nickel Catalysts ◽  
Nanoparticle Growth ◽  
Methanation Reaction ◽  
Supported Nickel Catalysts

scholarly journals Optimization of the Lipase Catalyzed Production of Structured Acylglycerols With Polyunsaturated Fatty Acids Isolated From Sardine Oil

2013 ◽  
Vol 2 (6) ◽  
pp. 97 ◽  
Author(s):  
Juan Antonio Noriega-Rodriguez ◽  
Esther Carrillo-Perez ◽  
Nohemi Gamez-Meza ◽  
Luis A. Medina-Juarez ◽  
Ramiro Baeza-Jimenez ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Polyunsaturated Fatty Acids ◽  
Immobilized Lipase ◽  
Reaction Times ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Molar Ratios ◽  
Sardine Oil ◽  
Different Temperatures ◽  
Urea Crystallization

<p>In the present work, direct enzyme-catalyzed esterification of n-3 polyunsaturated fatty acids (n-3 PUFA) isolated from sardine oil was optimized to obtain structured acyglycerols. A n-3 PUFA concentrate was prepared by urea crystallization of refined sardine oil and esterification was carried out mixing free fatty acids and glycerol at different molar ratios (<em>M</em> = 0.48, 1.5, 3.0, 4.5 and 5.52 mol/mol), using an immobilized lipase preparation from <em>Candida antarctica</em> (NV-435) at different temperatures (<em>T</em> = 38, 45, 55, 65 and 72 °C) and reaction times (<em>t</em> = 0.7, 2.75, 5.75, 8.75 and 10.8 h) in a rotatable central composition design. The degree of esterification was determined by analysis of the acylglycerides produced, using liquid chromatography (HPLC-ELSD). Optimization by response surface methodology (RSM) showed that in order to obtain higher esterification levels of n-3 PUFA to glycerol (99.5%), a molar ratio of 1.3 mol n-3 PUFA/mol glycerol, time 8.3 h and temperature 38 °C, are required. However, results of this work show that it is possible to drive the reaction to any determined product (MAG, DAG or TAG) by modifying the reaction conditions.</p>

scholarly journals Synthesis of High-Purity Silica Nanoparticles by Sol-Gel Method

2017 ◽  
Vol 19 (4) ◽  
pp. 295 ◽  
Author(s):  
S.V. Lazareva ◽  
N.V. Shikina ◽  
L.E. Tatarova ◽  
Z.R. Ismagilov
Keyword(s):  
Particle Size ◽  
Sol Gel ◽  
Sio2 Content ◽  
Reaction Conditions ◽  
Minimum Particle Size ◽  
Size Stability ◽  
Different Temperatures ◽  
Acid Catalyzed ◽  
Silica Sols ◽  
Hydrolysis Of

Colloidal silica (silica sol) nanoparticles were synthesized by ammonia- and hydrochloric acid-catalyzed hydrolysis of tetraethoxysilane with subsequent condensation and polymerization. Silica particles with the size of 12‒160 nm were obtained at different temperatures and ratios of the initial reactants and studied by means of TEM, AFM, IR spectroscopy and zeta-potential measurements. The reaction conditions providing the minimum particle size in the final product of the most complete hydrolysis were determined. At pH above 8.5, an increase in the SiO2 content of the sol to 23 wt.% did not change the particle size. At a low (~ 1.8 wt.%) SiO2 content of the sol, a wide variation in pH also did not exert a significant effect on the particle size. Stability of the silica sols synthesized in an alkaline medium was enhanced by the replacement of alcohol with water during evaporation at pH 8.5‒9.5. The possibility to produce silica sols with the required characteristics (particle size, pH, stability, purity, and SiO2 content in an aqueous or alcohol medium) makes them applicable in various industries.

The influence of nickel content on the performance of hydrotalcite-derived catalysts in CO 2 methanation reaction

2017 ◽  
Vol 42 (37) ◽  
pp. 23548-23555 ◽  
Author(s):  
Dominik Wierzbicki ◽  
Rafał Baran ◽  
Radosław Dębek ◽  
Monika Motak ◽  
Teresa Grzybek ◽  
...  
Keyword(s):  
Nickel Content ◽  
Methanation Reaction

scholarly journals Mechanism of aniline adsorption on post-crosslinked resins: pore structure and oxygen content

2018 ◽  
Vol 78 (10) ◽  
pp. 2096-2103 ◽  
Author(s):  
Wenhao Yu ◽  
Chao Xu ◽  
Chai Yin ◽  
Shitao Yu ◽  
Weizhi Sun ◽  
...  
Keyword(s):  
Pore Structure ◽  
Adsorption Capacity ◽  
Oxygen Content ◽  
Order Model ◽  
Reaction Conditions ◽  
First Order ◽  
Different Temperatures ◽  
Styrene Divinylbenzene ◽  
Diffusion Rates ◽  
The Difference

Abstract A series of post-crosslinked resins were synthesized from macroporous chloromethylated styrene-divinylbenzene copolymer by controlling post-crosslinked reaction conditions. Adsorption study towards aniline showed that the three resins, ST-DVB-WH5, ST-DVB-WH6, and ST-DVB-WH7, prepared at different temperatures, and which had nearly identical static adsorption capacity, displayed great disparity in kinetic behavior. The rate constant of ST-DVB-WH7 by the pseudo-first-order model was 1.50 and 1.19 times higher than that of ST-DVB-WH5 and ST-DVB-ST-DVB-WH6. Further analysis of the diffusion model showed that the three resins exhibited different diffusion rates due to the difference in oxygen content and pore structure of each resin. The results showed that the adsorption capacity was mainly decided by the pore volume within 1.14 and 3.42 nm and the adsorption rate was mainly decided by the oxygen content of the resin. In addition, as the best synthetic resin for aniline adsorption, the equilibrium adsorption capacity of ST-DVB-WH7 was 1.57 times and 1.44 times higher than that of H-103 and NKA-II, respectively.

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