scholarly journals Sintering-resistant Pt@CeO2 nanoparticles for high-temperature oxidation catalysis

Nanoscale ◽  
2016 ◽  
Vol 8 (19) ◽  
pp. 10219-10228 ◽  
Author(s):  
Siwon Lee ◽  
Jongsu Seo ◽  
WooChul Jung
Keyword(s):  
High Temperature ◽  
Methane Oxidation ◽  
High Temperature Oxidation ◽  
Reaction Rate ◽  
Ceo2 Nanoparticles ◽  
Oxidation Catalysis ◽  
Core Shell ◽  
Temperature Oxidation

We successfully synthesized shell-controllable Pt@CeO2 core–shell nanocomposites for high-temperature oxidation catalysis. We showed a T10 lower by 100 °C and an eight-fold higher reaction rate compared to a bare mixture of Pt and CeO2 nanoparticles, while maintaining complete methane oxidation for more than 50 h at 700 °C.

Analytical Formulas for In-Situ Combustion

SPE Journal ◽  
2011 ◽  
Vol 16 (03) ◽  
pp. 513-523 ◽  
Author(s):  
A.A.. A. Mailybaev ◽  
J.. Bruining ◽  
D.. Marchesin
Keyword(s):  
Oxygen Consumption ◽  
High Temperature ◽  
Heat Wave ◽  
High Temperature Oxidation ◽  
Reaction Rate ◽  
Temperature Oxidation ◽  
Light Oil ◽  
Oil Components ◽  
Combustion Regimes

Summary There is a renewed interest in using combustion to recover medium- or high-viscosity oil. Despite numerous experimental, numerical, and analytical studies, the mechanisms for incomplete fuel combustion or oxygen consumption are not fully understood. Incomplete oxygen consumption may lead to low-temperature oxidation reactions downstream. This paper shows that these features emerge in a relatively simple 1D model, where air is injected in a porous medium filled with inert gas, water, and an oil mixture consisting of precoke, medium oil, and light oil. Precoke is a component that is dissolved in the oil but has essentially the same composition as coke. At high temperatures, precoke is converted to coke, which participates in high-temperature oxidation. At high temperatures, medium-oil components are cracked, releasing gaseous oil. Light-oil components and water are vaporized. The model possesses an analytical solution, which was obtained by a concept introduced by Zeldovich et al. (1985). This concept, which underlies most analytical approaches such as the reaction-sheet approximation and large-activation-energy asymptotics, entails that reaction can occur only in a very small temperature range because of the highly nonlinear nature of the Arrhenius factor. For a temperature below this range, the reaction rate is too slow, and for temperatures above this range, the reaction rate is so fast that either the fuel or oxygen concentrations become zero. The model results, in the absence of external heat losses, show that there are two combustion regimes in which coke or oxygen is partially consumed. In one regime, the reaction zone moves in front of the heat wave; whereas, in the other regime, the order of the waves is reversed. There are also two combustion regimes in which the coke and oxygen are completely consumed. Also, here the reaction zone can move in front of or at the back of the heat wave. Each combustion regime is described by a sequence of waves; we derive formulas for parameters in these waves. We analyze our formulas for typical in-situ-combustion data and compare the results with numerical simulation. The main conclusion is that mainly two key parameters (i.e., the injected oxygen mole fraction and the fuel concentration) determine the combustion-front structure and when either incomplete oxygen consumption or incomplete fuel consumption occurs in the high-temperature oxidation zone.

Synthesis of Ni-CeO2 Nanocomposite Coatings by Electroforming

2012 ◽  
Vol 248 ◽  
pp. 48-53
Author(s):  
Ning Song Qu
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Weight Percent ◽  
Ceo2 Nanoparticles ◽  
Nano Particles ◽  
Nanocomposite Coatings ◽  
Temperature Oxidation ◽  
Nickel Coatings

In this paper, the effect of CeO2 nanoparticles content in the bath on the weight percent of CeO2 particles, morphology, texture, and high temperature oxidation resistance of the nanocomposite coatings was examined. With a rise in the loadings of CeO2 particles in the bath from 10 gl-1 to 40 gl-1, the CeO2 particles weight percent in the nanocomposite coatings gradually increases. Further increased the loadings of particles in the bath to 50 gl-1, the weight percent reversely reduces. The maximum of CeO2 nano particles weight percent in the nanocomposite coatings is 4.98 wt% obtained at current density of 3 Adm-2 from the bath containing 40 gl-1 CeO2 particles. The high temperature oxidation resistance of Ni-CeO2 nanocomposite coatings significantly rise compared with that of bare nickel coatings, and enhanced with a rise in the loadings of CeO2 nano particles from 10 gl-1 to 30 gl-1. The wear resistance of deposits is also consist with the nanoparticles content in the bath。

High temperature oxidation of iron–iron oxide core–shell nanowires composed of iron nanoparticles

2016 ◽  
Vol 18 (5) ◽  
pp. 3900-3909 ◽  
Author(s):  
M. Krajewski ◽  
K. Brzozka ◽  
W. S. Lin ◽  
H. M. Lin ◽  
M. Tokarczyk ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Iron Nanoparticles ◽  
Void Coalescence ◽  
Core Shell ◽  
Temperature Oxidation ◽  
Iron Iron ◽  
Iron Oxide Core ◽  
Iron Nanowires ◽  
Shell Nanowires

The thermal oxidation of iron nanowires causes their breakdown due to void coalescence and formation of α-Fe2O3microparticles and microrods.

High-Temperature Oxidation Kinetics of Galvalume-Coated Steel Sheet

2011 ◽  
Vol 402 ◽  
pp. 138-141
Author(s):  
Yue Wu ◽  
Qun Luo ◽  
Biao Zhou ◽  
Feng Jin ◽  
Qian Li
Keyword(s):  
High Temperature ◽  
Oxidation Reaction ◽  
High Temperature Oxidation ◽  
Steel Sheet ◽  
Reaction Rate ◽  
Coated Steel ◽  
Temperature Oxidation ◽  
Coated Steel Sheet ◽  
Kinetics Of ◽  
Oxidation Reaction Rate

The high-temperature oxidation kinetics of Galvalume-coated steel sheet and Q235 steel sheet were studied by thermogravimetric analysis (TGA). A new diffusion equation was deduced and used to investigate their kinetic mechanism. The characteristic time (tc) in the equation can be expressed as a function of temperature T, diffusion coefficient D0, thickness of the steel sheet H, etc. The calculated result showed that the oxidation reaction rate of Galvalume-coated steel sheet was slower than that of Q235 steel sheet through comparing the values of tc. Besides, the oxidation reaction rate increased with the temperature rising from 750 to 850 °C. Compared our experimental data with the theoretical value calculated by the new function, a good agreement has been obtained.

Behaviour of copper during the high temperature oxidation of steels produced by the electric furnace route

2003 ◽  
Vol 100 (1) ◽  
pp. 73-82
Author(s):  
Y. Riquier ◽  
D. Lassance ◽  
I. Li ◽  
J. M. Detry ◽  
A. Hildenbrand
Keyword(s):  
High Temperature ◽  
Electric Furnace ◽  
High Temperature Oxidation ◽  
Temperature Oxidation

High Temperature Oxidation Behaviors of Fe-Cr-Al Based Powder Porous Metal and a Strip

2013 ◽  
Vol 51 (10) ◽  
pp. 743-751 ◽  
Author(s):  
Seon-Hui Lim ◽  
Jae-Sung Oh ◽  
Young-Min Kong ◽  
Byung-Kee Kim ◽  
Man-Ho Park ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Porous Metal ◽  
Temperature Oxidation ◽  
Oxidation Behaviors

Effect of CaO Addition on the High-Temperature Oxidation of Mg Alloys

2016 ◽  
Vol 54 (6) ◽  
pp. 390-399 ◽  
Author(s):  
Dong Bok Lee ◽  
Shae Kwang Kim ◽  
Soon Yong Park
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Mg Alloys ◽  
Temperature Oxidation
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