scholarly journals A kinetic study of Co oxidation over the perovskite-like oxide LaSrNio4

2010 ◽  
Vol 75 (2) ◽  
pp. 249-258 ◽  
Author(s):  
Kejun Wang ◽  
Ping Zhong
Keyword(s):  
Activation Energy ◽  
Co Oxidation ◽  
Reaction Order ◽  
Space Velocity ◽  
Potential Candidate ◽  
Weight Hourly Space Velocity ◽  
Rate Determining Step ◽  
Co Oxidation Reaction ◽  
Oxygen Dissociation ◽  
Reaction Orders

The effect of reactant/product concentrations, reaction temperature and contact time on CO oxidation was investigated, using the perovskite-like oxide LaSrNiO4 as the catalyst. It was found that the reaction order of CO (reactant), as well as that of CO2 (product), is negative, the reaction orders for CO and CO2 being -0.32 and -0.51, respectively. However, the reaction order for O2 is positive, having a value of 0.62. The negative reaction order of CO and CO2 might be due to their competitive adsorption with O2, preventing the proceeding of oxygen dissociation (the rate-determining step of the reaction). The activation energy (Ea) of the reaction was calculated to be 49.3 kJ mol-1; this small activation energy suggests that LaSrNiO4 is a potential candidate for the CO oxidation reaction. The optimum weight hourly space velocity (WHSV) of the reaction was found to be 0.6 g s cm-3. The reaction conditions in the present case were (0.5-1 % CO + 0.5-2 % O2 + 0-2 % CO2), with He as the balance gas.

scholarly journals Kinetics of the Carbon Monoxide Oxidation Reaction Under Microwave Heating

1996 ◽  
Vol 430 ◽  
Author(s):  
W. Lee Perry ◽  
Joel D. Katz ◽  
Daniel Rees ◽  
Mark T. Paffett ◽  
Abhaya Datye
Keyword(s):  
Activation Energy ◽  
Carbon Monoxide ◽  
Co Oxidation ◽  
Microwave Heating ◽  
Oxidation Reaction ◽  
Reaction Order ◽  
Thermal Gradients ◽  
Exponential Factor ◽  
Co Oxidation Reaction ◽  
Kinetics Of

Abstract915 MHz microwave heating has been used to drive the CO oxidation reaction over Pd/Al2O3 without significantly affecting the reaction kinetics. As compared to an identical conventionally heated system, the activation energy, pre-exponential factor, and reaction order with respect to CO were unchanged. Temperature was measured using a thermocouple extrapolation technique. Microwave-induced thermal gradients were found to play a significant role in kinetic observations.

The Fushun Oil Shale Semi-Coke’s Combustion Features and Thermal Dynamic Analysis

2014 ◽  
Vol 694 ◽  
pp. 327-331
Author(s):  
Yan Chang Li ◽  
Yu Meng Yang
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Low Temperature ◽  
Heating Rate ◽  
Oil Shale ◽  
Reaction Order ◽  
Ignition Point ◽  
Reaction Orders ◽  
Combustion Features ◽  
High Temperature Condition

This study analyses the Fushun oil shale semi-coke samples prepared in 450°C, 550°C and 650°C by using STA449 TGA. The experiment studied their ignition points, concluded that with the ascent of the char-making-temperature the semi-coke’s ignition point is getting higher. The test used Coats-Redfern way to study the semi-coke’s activation energy. The result shows the semi-coke’s thermal dynamic model needs two different reaction orders in different temperature. In low temperature the reaction order is n=1; in high temperature it is n=3. When the temperature is low (n=1), the activation energy doesn’t influenced by the heating rate. In high temperature condition the activation energy is getting bigger with the ascent of the heating rate.

High activity and negative apparent activation energy in low-temperature CO oxidation – present on Au/Mg(OH)2, absent on Au/TiO2

2017 ◽  
Vol 7 (18) ◽  
pp. 4145-4161 ◽  
Author(s):  
Y. Wang ◽  
D. Widmann ◽  
M. Wittmann ◽  
F. Lehnert ◽  
D. Gu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Ir Spectroscopy ◽  
Co Oxidation ◽  
Oxidation Reaction ◽  
Reaction Behavior ◽  
Co Oxidation Reaction ◽  
Wide Range ◽  
Low Temperature Co Oxidation

Aiming at a better understanding of the unusual low-temperature CO oxidation reaction behavior on Au/Mg(OH)2 catalysts, we investigated this reaction mainly by combined kinetic and in situ IR spectroscopy measurements over a wide range of temperatures, from −90 °C to 200 °C.

Study of Errors on Larch Wood Pyrolysis Kinetic Analysis

2015 ◽  
Vol 1096 ◽  
pp. 243-247
Author(s):  
Lan Shu Xu ◽  
Yi Cheng ◽  
Yu Yu Li ◽  
Rui Li
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Reaction Order ◽  
Frequency Factor ◽  
Larch Wood ◽  
Wood Pyrolysis ◽  
Integral Methods ◽  
True Value ◽  
Reaction Orders ◽  
Pyrolysis Kinetic

Errors was generate when use integral methods to calculate pyrolysis kinetic. It was analyzed by considered the effects of methods and reaction orders. A α-T curve was established for the error discussion depending on basic kenotic theory. For analysis methods, both single curve and multiple curve methods can obtain reliable activation energy values (≤3%), but the error of frequency factor was significant (up to 40%). Frequency factor is sensitive to intercept changing and is also to reaction order. Magnitude error could show if reaction order deviates to true value.

Curing Reaction Kinetics of Epoxy/MWCNT-P Composites

2013 ◽  
Vol 634-638 ◽  
pp. 1896-1900 ◽  
Author(s):  
Li Jiao Sun ◽  
Ya Huang ◽  
Xiao Ting Chen
Keyword(s):  
Activation Energy ◽  
Reaction Order ◽  
Diglycidyl Ether ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Lower Activation ◽  
Multi Walled Carbon Nanotubes ◽  
Reaction Orders ◽  
Walled Carbon Nanotubes ◽  
Kinetics Of

The effects of the functionalized multi-walled carbon nanotubes (MWCNT-P) on the curing behavior of a diglycidyl ether of bisphenol-A epoxy (DGEBA) in the presence of 4,4'-methylenedianiline were investigated by non-isothermal differential scanning calorimetry. Activation energy (Ea) was obtained through Kissinger and Ozawa methodsItalic text respectively, and reaction order(n) was educed by Crane equation. The results showed that the addition of MWCNT-P enhanced the cure reaction of DGEBA with 4,4'-methylenedianiline, compared with pure epoxy system, epoxy containing MWCNT-P exhibited a lower activation energy. Both systems presented the same reaction orders, which indicated MWCNT-P did not change the auto-catalytic cure reaction mechanism of the epoxy resin.

Pt-Pd Nanoalloy for the Unprecedented Activation of Carbon-Fluorine Bond at Low Temperature

2019 ◽  
Author(s):  
Raghu Nath Dhital ◽  
keigo nomura ◽  
Yoshinori Sato ◽  
Setsiri Haesuwannakij ◽  
Masahiro Ehara ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Dft Calculations ◽  
Bond Activation ◽  
Mild Conditions ◽  
Selective Transformation ◽  
Rate Determining Step ◽  
Highly Active ◽  
Harsh Conditions ◽  
Reaction Profile

Carbon-Fluorine (C-F) bonds are considered the most inert organic functionality and their selective transformation under mild conditions remains challenging. Herein, we report a highly active Pt-Pd nanoalloy as a robust catalyst for the transformation of C-F bonds into C-H bonds at low temperature, a reaction that often required harsh conditions. The alloying of Pt with Pd is crucial to activate C-F bond. The reaction profile kinetics revealed that the major source of hydrogen in the defluorinated product is the alcoholic proton of 2-propanol, and the rate-determining step is the reduction of the metal upon transfer of the <i>beta</i>-H from 2-propanol. DFT calculations elucidated that the key step is the selective oxidative addition of the O-H bond of 2-propanol to a Pd center prior to C-F bond activation at a Pt site, which crucially reduces the activation energy of the C-F bond. Therefore, both Pt and Pd work independently but synergistically to promote the overall reaction

Some Aspects of the Electroreduction of Niazid to Nicotinamide on Mercury Electrodes in Acidic Media

1992 ◽  
Vol 57 (9) ◽  
pp. 1836-1842 ◽  
Author(s):  
Rafael Marín Galvín ◽  
José Miguel Rodríguez Mellado
Keyword(s):  
Electron Transfer ◽  
Essential Role ◽  
Uv Spectroscopy ◽  
Acidic Media ◽  
Polarographic Wave ◽  
Rate Determining Step ◽  
Tafel Slopes ◽  
Reaction Orders ◽  
Mercury Electrodes ◽  
The Waves

The electroreduction of niazid on mercury electrodes has been studied in acidic media (pH < 6). Tafel slopes and reaction orders were obtained at potentials corresponding to the foot of the first polarographic wave. On the basis of both polarographic and voltammetric results it has been shown that the waves appearing at more negative potentials correspond to the reduction of nicotinamide. Protonation of niazid plays an essential role in its reduction and pK values of 1.4, 3.2 and 11.5 were obtained by UV spectroscopy. The process corresponding to the first wave is irreversible, being the second one-electron transfer the rate determining step. Above pH 4 the process is complex due to the overlapping of the waves caused by the occurrence of protonation reactions.

Catalyst Selection for Hydrogenation of 1,2-Dihydroacenaphthylene

1998 ◽  
Vol 63 (11) ◽  
pp. 1945-1953 ◽  
Author(s):  
Jiří Hanika ◽  
Karel Sporka ◽  
Petr Macoun ◽  
Vladimír Kysilka
Keyword(s):  
Activation Energy ◽  
Nickel Catalyst ◽  
Palladium Catalyst ◽  
Active Component ◽  
Reaction Order ◽  
Nickel Catalysts ◽  
Practical Application ◽  
Repeated Use ◽  
Selection For ◽  
Catalyst Selection

The activity of ruthenium, palladium, and nickel catalysts for the hydrogenation of 1,2-dihydroacenaphthylene in cyclohexane solution was studied at temperatures up to 180 °C and pressures up to 8 MPa. The GC-MS technique was used to identify most of the perhydroacenaphthylene stereoisomers, whose fractions in the product were found dependent on the nature of the active component of the catalyst. The hydrogenation was fastest on the palladium catalyst (3% Pd/C). The nickel catalyst Ni-NiO/Al2O3, which is sufficiently active also after repeated use, can be recommended for practical application. The activation energy of 1,2-dihydroacenaphthylene hydrogenation using this catalyst is 17 kJ/mol, the reaction order with respect to hydrogen is unity.

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.

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