Detailed Kinetic Modeling of Iron Nanoparticle Synthesis from the Decomposition of Fe(CO)5
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- 作者：John Z. Wen ; C. Franklin Goldsmith ; Robert W. Ashcraft ; William H. Green
- 刊名：Journal of Physical Chemistry C
- 出版年：2007
- 出版时间：April 19, 2007
- 年：2007
- 卷：111
- 期：15
- 页码：5677 - 5688
- 全文大小：193K
- 年卷期：v.111,no.15(April 19, 2007)
- ISSN：1932-7455
文摘
A detailed chemical kinetic model for gas-phase synthesis of iron nanoparticles is presented in this work.The thermochemical data for Fen clusters (n 
2), iron carbonyls, and iron-cluster complexes with CO werecomputed using density functional theory at the B3PW91/6-311+G(d) level of theory. Chemically activatedand fall-off reaction rates were estimated by the QRRK method and three-body reaction theory. Kinetic modelswere developed for two pressures (0.3 and 1.2 atm) and validated against literature shock-tube measurementsof Fe concentrations and averaged nanoparticle diameters. The new model indicates that the nanoparticleformation chemistry is much more complex than that assumed in earlier studies. For the important temperaturerange near 800 K in a CO atmosphere, the Fe atom formation and consumption are largely controlled by thechemistry of Fe(CO)2, especially the reactions Fe(CO)2 
FeCO + CO, Fe + Fe(CO)2 Fe2CO + CO, andFe(CO)2 + Fe(CO)2 Fe2(CO)3 + CO. The decomposition of Fe(CO)5 is restricted by the rate of the spin-forbidden reaction, Fe(CO)5 Fe(CO)4 + CO. This model facilitates the understanding of how the reactionconditions affect the yield and size distribution of iron nanoparticles, which will be a crucial aspect in thegas-phase synthesis of carbon nanotubes.
2), iron carbonyls, and iron-cluster complexes with CO werecomputed using density functional theory at the B3PW91/6-311+G(d) level of theory. Chemically activatedand fall-off reaction rates were estimated by the QRRK method and three-body reaction theory. Kinetic modelswere developed for two pressures (0.3 and 1.2 atm) and validated against literature shock-tube measurementsof Fe concentrations and averaged nanoparticle diameters. The new model indicates that the nanoparticleformation chemistry is much more complex than that assumed in earlier studies. For the important temperaturerange near 800 K in a CO atmosphere, the Fe atom formation and consumption are largely controlled by thechemistry of Fe(CO)2, especially the reactions Fe(CO)2 FeCO + CO, Fe + Fe(CO)2 Fe2CO + CO, andFe(CO)2 + Fe(CO)2 Fe2(CO)3 + CO. The decomposition of Fe(CO)5 is restricted by the rate of the spin-forbidden reaction, Fe(CO)5 Fe(CO)4 + CO. This model facilitates the understanding of how the reactionconditions affect the yield and size distribution of iron nanoparticles, which will be a crucial aspect in thegas-phase synthesis of carbon nanotubes.