scholarly journals Oxygen exchange at gas/oxide interfaces: how the apparent activation energy of the surface exchange coefficient depends on the kinetic regime

2016 ◽  
Vol 18 (32) ◽  
pp. 22031-22038 ◽  
Author(s):  
Peter Fielitz ◽  
Günter Borchardt
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Oxygen Exchange ◽  
Oxide Surfaces ◽  
Kinetic Regime ◽  
Exchange Coefficient ◽  
Surface Exchange ◽  
Oxide Interfaces ◽  
Surface Exchange Coefficient ◽  
Apparent Activation Energies

The model explains the range of apparent activation energies measured in different kinetic regimes of oxygen exchange at oxide surfaces.

Oxygen diffusion and surface exchange in the mixed conducting oxides SrTi1−yFeyO3−δ

2016 ◽  
Vol 18 (42) ◽  
pp. 29495-29505 ◽  
Author(s):  
Veronika Metlenko ◽  
WooChul Jung ◽  
Sean R. Bishop ◽  
Harry L. Tuller ◽  
Roger A. De Souza
Keyword(s):  
Oxygen Diffusion ◽  
Oxygen Exchange ◽  
Exchange Coefficient ◽  
Surface Exchange ◽  
Conducting Oxides ◽  
Single Mechanism ◽  
Surface Exchange Coefficient

Variation of the surface exchange coefficient with Fe concentration suggests single mechanism of oxygen exchange for e−-poor and e−-rich SrTi1−yFeyO3−δ oxides.

scholarly journals Effect of CaO on catalytic combustion of semi-coke

2021 ◽  
Vol 10 (1) ◽  
pp. 011-020
Author(s):  
Luyao Kou ◽  
Junjing Tang ◽  
Tu Hu ◽  
Baocheng Zhou ◽  
Li Yang
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Combustion Rate ◽  
Activation Energies ◽  
Combustion Reaction ◽  
Tg Analysis ◽  
Conversion Rates ◽  
Apparent Activation Energies ◽  
Ozawa Integral Method ◽  
Addition Amount

Abstract Generally, adding a certain amount of an additive to pulverized coal can promote its combustion performance. In this paper, the effect of CaO on the combustion characteristics and kinetic behavior of semi-coke was studied by thermogravimetric (TG) analysis. The results show that adding proper amount of CaO can reduce the ignition temperature of semi-coke and increase the combustion rate of semi-coke; with the increase in CaO content, the combustion rate of semi-coke increases first and then decreases, and the results of TG analysis showed that optimal addition amount of CaO is 2 wt%. The apparent activation energy of CaO with different addition amounts of CaO was calculated by Coats–Redfern integration method. The apparent activation energy of semi-coke in the combustion reaction increases first and then decreases with the increase in CaO addition. The apparent activation energies of different samples at different conversion rates were calculated by Flynn–Wall–Ozawa integral method. It was found that the apparent activation energies of semi-coke during combustion reaction decreased with the increase in conversion.

A Study of the Oxygen Surface Exchange Coefficient on La0.5Sr0.5CoO3−δ Thin Films

1999 ◽  
Vol 606 ◽  
Author(s):  
X. Chen ◽  
S. Wang ◽  
Y.L. Yang ◽  
L. Smith ◽  
N.J. Wu ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Initial Pressure ◽  
Transient Behavior ◽  
Epitaxial Thin Films ◽  
Exchange Coefficient ◽  
Surface Exchange ◽  
Surface Exchange Coefficient ◽  
Pressure Changes ◽  
Oxygen Surface Exchange

AbstractLa0.5Sr0.5CoO3−δ (LSCO) can be used as a cathode material for low temperature solid oxide fuel cell applications. LSCO epitaxial thin films have been deposited on LaAlO3 substrates by pulsed laser deposition (PLD). The transient behavior of the thin film conductivity with the pressure changes was recorded as a function of temperature and partial oxygen pressure. The surface exchange coefficient k of the LSCO thin film was obtained from analysis of the electrical conductivity relaxation data. The measured surface exchange coefficient increases with temperature and with final pressure but is not sensitive to the initial pressure. After prolonged annealing at 900°C, the k value was found to have greatly increased. The mechanism of the dependence of the measured k on pressure is discussed.

scholarly journals Back-exchange: a novel approach to quantifying oxygen diffusion and surface exchange in ambient atmospheres

2017 ◽  
Vol 19 (19) ◽  
pp. 12199-12205 ◽  
Author(s):  
Samuel J. Cooper ◽  
Mathew Niania ◽  
Franca Hoffmann ◽  
John A. Kilner
Keyword(s):  
Isotopic Exchange ◽  
Ambient Air ◽  
Exchange Coefficient ◽  
Effective Surface ◽  
Surface Exchange ◽  
Electronic Conductor ◽  
Novel Approach ◽  
Mixed Ionic Electronic Conductor ◽  
Back Exchange ◽  
Surface Exchange Coefficient

A novel two-step Isotopic Exchange (IE) technique has been developed to investigate the influence of oxygen containing components of ambient air (such as H2O and CO2) on the effective surface exchange coefficient (k*) of a common mixed ionic electronic conductor material.

Determination of the Apparent Activation Energy of Concrete by Adiabatic Test

2011 ◽  
Vol 477 ◽  
pp. 411-417
Author(s):  
Jia Chun Wang
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Temperature Rise ◽  
Adiabatic Temperature Rise ◽  
Study Results ◽  
Stage Development ◽  
Concrete Hydration ◽  
Apparent Activation Energies ◽  
Influence Of Hydration

It is known that apparent activation energy of the binders in concrete characterizes the sensitivity of concrete hydration processes to temperature. In this paper the apparent activation energies of concretes containing different complex binders have been determined through adiabatic temperature rise test. The influence of hydration emission heat on the apparent activation energy of concrete is studied. The study results show that the apparent activation energy is decreasing with the hydration of binder stage development.

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