Effect of carbon dioxide on the activation energy for methyl radical generation over lithium/magnesia catalysts

1992 ◽  
Vol 96 (15) ◽  
pp. 6395-6398 ◽  
Author(s):  
Mingting Xu ◽  
Chunlei Shi ◽  
Xuemin Yang ◽  
Michael P. Rosynek ◽  
Jack H. Lunsford
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Methyl Radical ◽  
Radical Generation

Gas Cell Infrared and Attenuated Total Reflection Infrared Spectroscopic Studies for Organic–Inorganic Interactions in Adsorption of Fulvic Acid on the Goethite Surface Generating Carbon Dioxide

2021 ◽  
pp. 000370282199121
Author(s):  
Yuki Nakaya ◽  
Satoru Nakashima ◽  
Takahiro Otsuka
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Fulvic Acid ◽  
Spectroscopic Studies ◽  
Reaction Model ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Gas Cell ◽  
Rate Determining Step ◽  
Ir Spectroscopic

The generation of carbon dioxide (CO2) from Nordic fulvic acid (FA) solution in the presence of goethite (α-FeOOH) was observed in FA–goethite interaction experiments at 25–80 ℃. CO2 generation processes observed by gas cell infrared (IR) spectroscopy indicated two steps: the zeroth order slower CO2 generation from FA solution commonly occurring in the heating experiments of the FA in the presence and absence of goethite (activation energy: 16–19 kJ mol–1), and the first order faster CO2 generation from FA solution with goethite (activation energy: 14 kJ mol–1). This CO2 generation from FA is possibly related to redox reactions between FA and goethite. In situ attenuated total reflection infrared (ATR-IR) spectroscopic measurements indicated rapid increases with time in IR bands due to COOH and COO– of FA on the goethite surface. These are considered to be due to adsorption of FA on the goethite surface possibly driven by electrostatic attraction between the positively charged goethite surface and negatively charged deprotonated carboxylates (COO–) in FA. Changes in concentration of the FA adsorbed on the goethite surface were well reproduced by the second order reaction model giving an activation energy around 13 kJ mol–1. This process was faster than the CO2 generation and was not its rate-determining step. The CO2 generation from FA solution with goethite is faster than the experimental thermal decoloration of stable structures of Nordic FA in our previous report possibly due to partial degradations of redox-sensitive labile structures in FA.

Activation Energy of Methyl Radical Decay in Methane Hydrate

2005 ◽  
Vol 109 (44) ◽  
pp. 21086-21088 ◽  
Author(s):  
Kei Takeya ◽  
Kouhei Nango ◽  
Takeshi Sugahara ◽  
Kazunari Ohgaki ◽  
Atsushi Tani
Keyword(s):  
Activation Energy ◽  
Methane Hydrate ◽  
Methyl Radical ◽  
Radical Decay

scholarly journals Regeneration of Adsorbents by the Use of Liquid, Subcritical and Supercritical Carbon Dioxide

2000 ◽  
Vol 18 (4) ◽  
pp. 347-371 ◽  
Author(s):  
Henryk Grajek
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Particle Size ◽  
Supercritical Carbon Dioxide ◽  
Adsorption And Desorption ◽  
Extraction Solvent ◽  
Desorption Temperature ◽  
Desorption Efficiency ◽  
The Subject ◽  
Supercritical Carbon

The literature concerning the adsorption and desorption of environmental impurities from adsorbents by means of liquid, subcritical and supercritical carbon dioxide and the author's work on the subject have been reviewed. The influence of the adsorption and desorption temperature, the pressure and the density of the extraction solvent, the solubility of the adsorbate in the extraction solvent, the activation energy for adsorbate desorption and the particle size of the adsorbent on the adsorbate desorption efficiency by this method were discussed.

Potential Role of Methyl-Radical Adducts with Carbon Dioxide in the Martian Atmosphere

2003 ◽  
Vol 9 (4) ◽  
pp. 287-294 ◽  
Author(s):  
Detlef Schröder ◽  
Marija Semialjac ◽  
Helmut Schwarz
Keyword(s):  
Carbon Dioxide ◽  
Potential Role ◽  
Martian Atmosphere ◽  
Methyl Radical

THE PHOTO-OXIDATION OF AZOMETHANE

1955 ◽  
Vol 33 (3) ◽  
pp. 496-506 ◽  
Author(s):  
G. R. Hoey ◽  
K. O. Kutschke
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Room Temperature ◽  
Major Product ◽  
Steric Factor ◽  
Primary Process ◽  
Methyl Radicals ◽  
Low Oxygen ◽  
Secondary Product ◽  
Photo Oxidation

The photo-oxidation of azomethane has been studied at low oxygen pressures (0.02 to 1 mm.) in the temperature range ca. 25 °C. to 161 °C. The primary process in the normal photolysis of azomethane is essentially unaffected by the presence of oxygen. Carbon monoxide is probably a secondary product of the oxidation of methyl radicals. Carbon dioxide formation is quite small, and therefore neither methyl radicals nor CH3N=N—CH2 radicals are oxidized appreciably to carbon dioxide. Nitrous oxide, which is a major product of the oxidation, is most likely formed from the oxidation of CH3N=NCH2 radicals. The suggested mechanism of N2O formation is:[Formula: see text] The reaction of methyl radicals with oxygen was found to proceed with a negligible activation energy and a steric factor of the order of 10−2. Evidence for the occurrence of the reactions[Formula: see text]at room temperature was obtained.

scholarly journals Pyrolysis of phenylmercaptoacetic acid

1968 ◽  
Vol 46 (2) ◽  
pp. 191-197 ◽  
Author(s):  
A. T. C. H. Tan ◽  
A. H. Sehon
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Carbon Monoxide ◽  
Acetic Acid ◽  
Rate Constant ◽  
Order Reaction ◽  
First Order Reaction ◽  
Kcal Mole ◽  
Dissociation Process ◽  
First Order

The pyrolysis of phenylmercaptoacetic acid was investigated by the toluene-carrier technique over the temperature range 760–835 °K. The main products of the decomposition were phenyl mercaptan, carbon dioxide, acetic acid, phenyl methyl sulfide, carbon monoxide, and dibenzyl.The overall decomposition was a first-order reaction with respect to phenylmercaptoacetic acid and could be represented by the two parallel steps:[Formula: see text]Reaction [1] was shown to be a homogeneous first-order dissociation process, and its rate constant was represented by the expression[Formula: see text]The activation energy of this reaction, i.e. 58 kcal/mole, was identified with D(C6H5S—CH2COOH).

Reaction Kinetics of Fe2O3 and BaCO3 to Prepare Ba2Fe2O5

2014 ◽  
Vol 33 (4) ◽  
pp. 319-323 ◽  
Author(s):  
Jun-Hao Liu ◽  
Guo-Hua Zhang ◽  
Kuo-Chih Chou
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Activation Energy ◽  
Global Warming ◽  
Reaction Kinetics ◽  
Isothermal Condition ◽  
Product Layer ◽  
Thermo Gravimetric ◽  
Thermo Gravimetric Analyzer ◽  
Kinetics Of

AbstractCarbon dioxide is a greenhouse gas and substantially affects the global warming and climate change, so study on the adsorption of carbon dioxide is very urgent. As a new CO2 captor, Ba2Fe2O5 was prepared by the solid state reaction of Fe2O3 with BaCO3, following formula Fe2O3 + 2BaCO3 = Ba2Fe2O5 + 2CO2. The reaction kinetics in isothermal condition was investigated by using the method of thermo-gravimetric analyzer (TGA). It was found that the reaction of Fe2O3 with BaCO3 was controlled by the diffusion step in the product layer, and the kinetics process could be described by the RPP model (Real Physical Picture) with the apparent activation energy extracted to be 161.122 kJ/mol.

scholarly journals Surprisingly facile CO2 insertion into cobalt alkoxide bonds: A theoretical investigation

2015 ◽  
Vol 11 ◽  
pp. 1340-1351 ◽  
Author(s):  
Willem K Offermans ◽  
Claudia Bizzarri ◽  
Walter Leitner ◽  
Thomas E Müller
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Density Functional Theory ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Activation Barrier ◽  
Density Functional Theory Calculations ◽  
Reaction Energy ◽  
Reaction Step ◽  
Functional Theory

Exploiting carbon dioxide as co-monomer with epoxides in the production of polycarbonates is economically highly attractive. More effective catalysts for this reaction are intensively being sought. To promote better understanding of the catalytic pathways, this study uses density functional theory calculations to elucidate the reaction step of CO2 insertion into cobalt(III)–alkoxide bonds, which is also the central step of metal catalysed carboxylation reactions. It was found that CO2 insertion into the cobalt(III)–alkoxide bond of [(2-hydroxyethoxy)CoIII(salen)(L)] complexes (salen = N,N”-bis(salicyliden-1,6-diaminophenyl)) is exothermic, whereby the exothermicity depends on the trans-ligand L. The more electron-donating this ligand is, the more exothermic the insertion step is. Interestingly, we found that the activation barrier decreases with increasing exothermicity of the CO2 insertion. Hereby, a linear Brønsted–Evans–Polanyi relationship was found between the activation energy and the reaction energy.

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