Oxidation of carbon monoxide by oxygen over pure and platinum-doped LaMnO3 perovskites

1990 ◽  
Vol 55 (8) ◽  
pp. 1928-1934 ◽  
Author(s):  
Jaroslav Bartoň ◽  
Vladimír Pour
Keyword(s):  
Activation Energy ◽  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Apparent Activation Energy ◽  
Co Oxidation ◽  
Reaction Kinetics ◽  
Empirical Equation ◽  
Catalytic Activities ◽  
Surface Areas ◽  
Oxidation Of Carbon Monoxide

The properties of pure and platinum-doped LaMnO3 perovskites, including their catalytic activities for the reaction of CO with oxygen, have been determined. Perovskite samples were prepared by decomposition of lanthanum and manganese citrates. The surface areas were 12.2 m2/g for pure LaMnO3 and 9.8 m2/g for the platinum-doped sample. The doping with a small amount of platinum markedly enhances the catalytic activity of LaMnO3 perovskite. The (CO + O2) reaction starts at 200 °C over LaMnO3 and at temperatures below 100 °C over a sample doped with Pt. The reaction kinetics for both the pure and platinum-doped LaMnO3 can be described by empirical equation (4). When Pt-doped perovskite is used, an increase in the apparent activation energy occurs at about 150 °C. This fact is attributed to a change in the mechanism of CO oxidation.

scholarly journals CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 131 ◽  
Author(s):  
Rola Mohammad Al Soubaihi ◽  
Khaled Mohammad Saoud ◽  
Myo Tay Zar Myint ◽  
Mats A. Göthelid ◽  
Joydeep Dutta
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Active Sites ◽  
Bond Activation ◽  
Dissociative Adsorption ◽  
High Catalytic Activity ◽  
Good Catalytic Activity ◽  
Pretreatment Conditions ◽  
Oxidation Efficiency

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

scholarly journals Apparent Activation Energy in Electrochemical Multistep Reactions: A Description via Degrees of Rate Control

2020 ◽  
Author(s):  
Alfredo Calderón-Cárdenas ◽  
Enrique A. Paredes-Salazar ◽  
Hamilton Varela
Keyword(s):  
Activation Energy ◽  
Catalytic Activity ◽  
Apparent Activation Energy ◽  
Chemical Kinetics ◽  
Rate Control ◽  
Rate Coefficients ◽  
Intrinsic Activity ◽  
Empirical Parameter ◽  
Heterogenous Catalysis ◽  
Multistep Reactions

<div> <div> <div> <p>Activation energy is a well-known empirical parameter in chemical kinetics that characterises the dependence of the chemical rate coefficients on the temperature and provides information to compare the intrinsic activity of the catalysts. However, the determination and interpretation of the apparent activation energy in multistep reactions is not an easy task. For this purpose, the concept of degree of rate control is convenient, which comprises a mathematical approach for analyzing reaction mechanisms and chemical kinetics. Although this concept has been used in catalysis, it has not yet been applied in electrocatalytic systems, whose ability to control the potential across the solid/liquid interface is the main difference with heterogenous catalysis, and the electrical current is commonly used as a measure of the reaction rate. Herein we use the definition of ‘degree of rate control for elementary step’ to address some of the drawbacks that frequently arise with interpreting apparent activation energy as a measure of intrinsic electrocatalytic activity of electrode. For this, an electrokinetic model Langmuir-Hinshelwood-like is used for making numerical experiments and verifying the proposed ideas. The results show that to improve the catalytic activity of an electrode material, it must act upon the reaction steps with the highest normalised absolute values of degree of rate control. On the other hand, experiments at different applied voltages showed that if the electroactive surface poisoning process take place, changes in 𝐸𝑎𝑝𝑝 can not be used to compare the catalytic activity of the electrodes. Finally, the importance of making measurements at steady-state to avoid large errors in the calculations of apparent activation energy is also discussed. </p> </div> </div> </div>

Effect of the exposed ceria morphology on the catalytic activity of gold/ceria catalysts for the preferential oxidation of carbon monoxide

2018 ◽  
Vol 344 ◽  
pp. 545-555 ◽  
Author(s):  
Mike Carltonbird ◽  
Srisin Eaimsumang ◽  
Sangobtip Pongstabodee ◽  
Supakorn Boonyuen ◽  
Siwaporn Meejoo Smith ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Preferential Oxidation ◽  
Ceria Catalysts ◽  
Oxidation Of Carbon Monoxide

Performance of Transition Metal Ions Exchanged Zeolite 13X in Greenhouse Gas Reduction

2007 ◽  
Author(s):  
K. S. Hui ◽  
Christopher Y. H. Chao ◽  
C. W. Kwong ◽  
M. P. Wan
Keyword(s):  
Activation Energy ◽  
Catalytic Activity ◽  
Transition Metal ◽  
Apparent Activation Energy ◽  
Surface Area ◽  
Active Sites ◽  
Methane Combustion ◽  
Bet Surface Area ◽  
Metal Loading ◽  
Zeolite 13X

This study investigated the performance of multi-transition metal (Cu, Cr, Ni and Co) ions exchanged zeolite 13X catalysts on methane emission abatement, especially at methane level of the exhaust from natural gas fueled vehicles. Catalytic activity of methane combustion using multi-ions exchanged catalyst was studied under different parameters: mole % of metal loading, inlet velocity and inlet methane concentration at atmospheric pressure and 500 °C. Performance of the catalysts was investigated and explained in terms of the apparent activation energy, number of active sites and BET surface area of the catalyst. This study showed that the multi-ions exchanged catalyst outperformed the single-ions exchanged and the acidified 13X catalysts. Lengthening the residence time could also lead to higher methane conversion %. Catalytic activity of the catalysts was influenced by the mole % of metal loading which played important roles in affecting the apparent activation energy of methane combustion, active sites and also the BET surface area of the catalyst. Increasing mole % of metal loading in the catalyst decreased the apparent activation energy for methane combustion and also the BET surface area of the catalyst. In view of these, there existed an optimized mole % of metal loading where the highest catalytic activity was observed.

THE KINETICS OF CUPRENE GROWTH

1950 ◽  
Vol 28b (7) ◽  
pp. 358-372
Author(s):  
Cyrias Ouellet ◽  
Adrien E. Léger
Keyword(s):  
Nitric Oxide ◽  
Activation Energy ◽  
Carbon Monoxide ◽  
Apparent Activation Energy ◽  
Copper Catalyst ◽  
Maximum Velocity ◽  
Static System ◽  
Reaction Velocity ◽  
First Order ◽  
Kinetics Of

The kinetics of the polymerization of acetylene to cuprene on a copper catalyst between 200° and 300 °C. have been studied manometrically in a static system. The maximum velocity of the autocatalytic reaction shows a first-order dependence upon acetylene pressure. The reaction is retarded in the presence of small amounts of oxygen but accelerated by preoxidation of the catalyst. The apparent activation energy, of about 10 kcal. per mole for cuprene growth between 210° and 280 °C., changes to about 40 kcal. per mole above 280 °C. at which temperature a second reaction seems to set in. Hydrogen, carbon monoxide, or nitric oxide has no effect on the reaction velocity. Series of five successive seedings have been obtained with cuprene originally grown on cuprite, and show an effect of aging of the cuprene.

The interplay between structural perfectness and CO oxidation catalysis on aluminum, phosphorous and silicon complexes of corroles

2019 ◽  
Vol 21 (14) ◽  
pp. 7661-7674 ◽  
Author(s):  
Afshan Mohajeri ◽  
Nasim Hassani
Keyword(s):  
Density Functional Theory ◽  
Carbon Monoxide ◽  
Co Oxidation ◽  
Catalytic Oxidation ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Oxidation Catalysis ◽  
Functional Theory ◽  
Oxidation Of Carbon Monoxide

Catalytic oxidation of carbon monoxide on perfect and defective structures of corrole complexes with aluminum, phosphorous and silicon have been investigated by performing density functional theory calculations.

CATALYTIC ACTIVITY FOR METHANE OXIDATION OF GOETHITE SUPPORTED ON ALUMINA

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4249-4254 ◽  
Author(s):  
KEI-ICHIRO MURAI ◽  
KOHEI TOMITA ◽  
SUGURU TOJO ◽  
TOSHIHIRO MORIGA ◽  
ICHIRO NAKABAYASHI
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Methane Oxidation ◽  
Model Experiment ◽  
The Other ◽  
Catalytic Activities ◽  
Surface Areas ◽  
Oxidation Of Methane ◽  
Other Hand ◽  
Specific Surface Areas

Two kinds of α- Fe 2 O 3 catalysts supported on χ- Al 2 O 3 and γ- Al 2 O 3 were synthesized. α- Fe 2 O 3 was prepared from α- FeOOH . As a model experiment, an investigation was made with the oxidation of methane. As all catalysts with various Fe contents supported on χ- Al 2 O 3 with various Fe contents had higher specific surface areas than those supported on γ- Al 2 O 3, α- Fe 2 O 3/χ- Al 2 O 3 catalyst has higher catalytic activities than α- Fe 2 O 3/γ- Al 2 O 3 catalyst. From SEM-EDS analyses, it is concluded that in α- Fe 2 O 3/χ- Al 2 O 3 catalyst, α- Fe 2 O 3 exists mainly on the surface of the support, because of flatness of the surface of χ- Al 2 O 3. On the other hand, in the case of α- Fe 2 O 3/γ- Al 2 O 3 catalyst, as the surface of support, γ- Al 2 O 3, is uneven, α- Fe 2 O 3 do not partially exist on the surface but in the pores.

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