scholarly journals On the Mechanism of Methane Conversion in the Nonсatalytic Processes of Its Thermal Pyrolysis and Steam and Carbon Dioxide Reforming

2021 ◽  
Author(s):  
E. Busillo ◽  
V. I. Savchenko ◽  
V. S. Arutyunov
Keyword(s):  
Carbon Dioxide ◽  
Methane Conversion ◽  
Carbon Dioxide Reforming ◽  
Temperature Range ◽  
Thermal Pyrolysis ◽  
First Order Kinetics ◽  
Initial Stage ◽  
Conversion Of Methane ◽  
Exponential Factors ◽  
Kinetics Of

Abstract A detailed kinetic modeling of the noncatalytic processes of thermal pyrolysis and steam and carbon dioxide reforming of methane revealed almost completely identical kinetics of the methane conversion in these processes. This suggests that, in the temperature range 1400–1800 K, the initial stage of conversion of methane in all these processes is its thermal pyrolysis. The modeling results agree well with the experimental data on methane pyrolysis. For the temperature range examined, the Arrhenius expressions (pre-exponential factors and activation energy) were obtained in the first-order kinetics approximation for the rate of methane conversion in the processes studied. The expressions derived may be useful for making preliminary estimates and carrying out engineering calculations.

KINETICS OF ADSORPTION OF ORGANIC AND INORGANIC PHOSPHATES BY SHORT-RANGE ORDERED PRECIPITATE OF ALUMINUM

1990 ◽  
Vol 70 (3) ◽  
pp. 461-470 ◽  
Author(s):  
C. SHANG ◽  
P. M. HUANG ◽  
J. W. B. STEWART
Keyword(s):  
Short Range ◽  
Kinetics Of Adsorption ◽  
Temperature Range ◽  
First Order Kinetics ◽  
Initial Ph ◽  
Two Stages ◽  
Relationship Of ◽  
Kinetics Of ◽  
Inorganic Phosphates ◽  
Phosphate Groups

The kinetics of the adsorption of orthophosphate (Pi), inositol hexaphosphate (IHP), inositol monophosphate (IMP) and glucose 6-phosphate (G6P) by short-range ordered precipitate of Al were studied at the initial pH 4.50 and in the temperature range of 278–308 K. This information is essential for understanding the rate and energy relationship of the adsorption of phosphates by short-range ordered Al precipitate. The amounts of Pi and IHP adsorbed by the Al precipitate were much higher than those of IMP and G6P adsorbed in the temperature range and reaction periods studied. The adsorption can be divided into two stages, a fast adsorption before 1 h and a slow adsorption between 1 and 24 h. The adsorption at both stages obeyed the first-order kinetics. Among all the phosphates studied, the adsorption of Pi proceeded most rapidly. The rate constants for the adsorption of IHP were much greater than those of G6P and IMP at the same temperature; this was attributed to the functionality of multiple phosphate groups of IHP. The Arrhenius activation energies for the adsorption of Pi, IHP, IMP and G6P, which were estimated from the slow reaction, were 48 ± 2, 89 ± 4, 100 ± 8 and 108 ± 10 KJ/mol P adsorbed, respectively. Key words: Organic phosphate, precipitate of aluminum, adsorption, rate constant, Arrhenius activation energy

Kinetics of Carbon Dioxide Reforming of Natural Gas Using Different Catalysts

2009 ◽  
Vol 27 (15) ◽  
pp. 1661-1673 ◽  
Author(s):  
S. A. El-Temtamy ◽  
S. A. Ghoneim ◽  
A. K. El-Morsy ◽  
A. Y. El-Naggar ◽  
R. A. El-Salamouny
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Carbon Dioxide Reforming ◽  
Kinetics Of

Kinetics of extraction of coal-tar pitch components with supercritical carbon dioxide

2007 ◽  
Vol 61 (1) ◽  
Author(s):  
S. Marković ◽  
Z. Marković ◽  
R. McCrindle ◽  
B. Simonović
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Coal Tar ◽  
Coal Tar Pitch ◽  
Extraction Kinetics ◽  
High Pitch ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
Supercritical Carbon

AbstractThe extraction of a coal-tar pitch with supercritical carbon dioxide was performed under optimal pressure, flow rate, and three different constant temperatures. The extraction kinetics was examined for each temperature and it was surprisingly found that the extraction rate of most components was governed by the first-order kinetics. It was assumed that this deviation from typical models of supercritical fluid extraction kinetics was caused by high pitch concentrations and low solubilities of the components.

Syngas Production via Carbon Dioxide Reforming of Methane in a Wall-Coated Monolith Reactor

2013 ◽  
Vol 805-806 ◽  
pp. 1257-1264
Author(s):  
Thanarak Srisurat ◽  
Karn Pana-Suppamassadu ◽  
Phavanee Narataruksa ◽  
Sabaithip Tungkamani ◽  
Monrudee Phongaksorn ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Volumetric Flow Rate ◽  
Molar Ratio ◽  
Carbon Dioxide Reforming ◽  
Syngas Production ◽  
Flow Channels ◽  
Monolith Reactor ◽  
Conversion Of Methane ◽  
The Stability ◽  
Gas Space

The production of syngas via carbon dioxide reforming or dry methane reforming (DMR) was studied in the present study. To reduce pressure drop and improve the performance, the reaction was carried out over a 10%Ni/Al2O3-MgO catalyst in a wall-coated monolith reactor at about 600°C, atmospheric pressure. The monolith reactor comprised of 37 circular flow channels of 3-mm-diameter. The reactant gases i.e. CH4and CO2at stoichiometric molar ratio of 1:2 was fed into the reactor at the volumetric flow rate of 450, 600 and 750 mL/min corresponding to various gas space velocities (GSV) i.e. 0.57, 0.76, and 0.96 s-1, respectively. Under 24-hr continuous operations, the stability of system could be sustained and the deactivation by carbon deposition was not observed. The experimental results did show that the conversion of methane depended upon the GSV i.e. the %CH4conversion were 50, 45 and 40% for the GSV of 0.57, 0.76, and 0.96 s-1, respectively. In addition, the %H2yield, %H2selectivity, %CO yield, %CO selectivity also depended on the feeding rate and so affected the performance of the wall-coated monolith reactor as a reformer.

Kinetics of the initial stage of initiated thermal oxidation of caprolactam and N-octylbutyramide

1981 ◽  
Vol 46 (11) ◽  
pp. 2650-2656 ◽  
Author(s):  
Božena Lánská ◽  
Ludvig Michailovich Postnikov ◽  
Albert Leonidovich Aleksandrov ◽  
Jan Šebenda
Keyword(s):  
Liquid Phase ◽  
Thermal Oxidation ◽  
Radical Reaction ◽  
Second Order ◽  
Peroxy Radicals ◽  
Oxidation Reactions ◽  
Temperature Range ◽  
Initial Stage ◽  
A Chain ◽  
Kinetics Of

The thermal oxidation of ε-caprolactam or N-octylbutyramide in the liquid phase is a chain radical reaction. In the initial stage, the only reaction product is the corresponding amide hydroperoxide, formed from peroxy radicals by a second-order termination reaction. The rates of thermal oxidation reactions initiated with 7,7'-dicumenyl peroxide or 1,1'-azodi(cyclohexanecarbonitrile) and the rates of initiation reactions were measured in the temperature range 80-130 °C. Using the values thus obtained, the ratios of rates of the propagation and termination steps, k2 . k6-1/2, characterizing the oxidizability compounds, were calculated.

scholarly journals Formation Kinetics of the Mixed Cyclopentane—Carbon Dioxide Hydrates in Aqueous Sodium Chloride Solutions

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4388
Author(s):  
Xuebing Zhou ◽  
Ye Zhang ◽  
Xiaoya Zang ◽  
Deqing Liang
Keyword(s):  
Carbon Dioxide ◽  
Mass Fraction ◽  
Hydrate Formation ◽  
Initial Pressure ◽  
Diffusion Resistance ◽  
X Ray Diffraction ◽  
Sodium Chloride Solutions ◽  
Formation Kinetics ◽  
Initial Stage ◽  
Kinetics Of

Hydrate formation from cyclopentane (CP) and carbon dioxide was measured at 281 K by powder X-ray diffraction (PXRD) and macroscopic methods. The effect of initial pressure and CP mass fraction in liquid phase was analyzed. The results showed that hydrate formation was assumed to start with the nucleation of the mixed CP-CO2 hydrate with small fraction of CO2 followed by a large continuous CO2 adsorption. Initial pressure was found to have a positive correlation with the total CO2 consumptions when the initial pressure was below 2.5 MPa. However, the total CO2 consumptions dropped by over a half as the initial pressure was 3.0 MPa. PXRD revealed that all the hydrate samples formed at different initial pressures were structure II. The CO2 consumptions were assumed to be inhibited by the competitive occupation of 51264 cages between CP and CO2 molecules when the initial pressure was above 2.5 MPa. The CO2 consumptions were also found to be reduced as the CP mass fraction was above 0.25. An excess of CP molecules was not assumed to strengthen the formation of the mixed CP-CO2 hydrates at the initial stage, but increased the thickness of liquid CP film at aqueous brine and hydrate particles, which increased the diffusion resistance of CO2 molecules. Therefore, the suitable initial pressure and the CP mass fraction for the mixed CP-CO2 hydrate formation should be around 2.5 MPa and 0.2, respectively.

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