Detailed modeling of soot formation in hydrocarbon pyrolysis

Крестинин, А. В.

doi:10.1016/s0010-2180(99)00167-4

Cited by 136 publications

(81 citation statements)

References 21 publications

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“…At some high temperature levels in EO/Ar plasma decomposition, the radicals and unsaturated molecules begin to combine leading, ultimately, to soot or highly carbonized structures. Krestinin (2000) and others (Vuitton et al, 2001) think that the soot may be formed via the acetylene pathway; i.e. polyyne model and the diacetylene, C 4 H 2, is recognized as a soot precursor.…”

Section: Comparison Of the Simulated Results With The Experimental Datamentioning

confidence: 99%

Reaction Mechanism of Ethylene Oxide at Various Oxygen/Ethylene Oxide Ratios in an RF Cold Plasma Environment

Liao

Wei

Hsieh

et al. 2005

Aerosol Air Qual. Res.

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An innovative method was used to simulate ethylene oxide (EO) oxidation in an RF plasma reactor. The objective of this work was to simulate the stable species mole fraction profiles measured in a flowing plasma system at constant temperature and pressure. The mechanism involved participation of 36 species in 140 elementary reactions. Sensitivity analysis was also performed to identify the order of significance of reactions in the mechanism of the model' s predictions. The results show that the main reactions for EO decomposition changed with a varying O 2 /EO ratio in the plasma system. That is to say, the most important reaction to the O 2 /EO ratio of zero was the electron dissociation reaction of EO, C 2 H 4 O + e- CH 3 CHO + e-. While, the most influential reaction for EO decomposition at O 2 /EO ratio of 5.0 was the formation reaction of HO 2 , which forms OH radicals, then enhances the decomposition of C 2 H 4 O by the reaction, C 2 H 4 O + OH = C 2 H 3 O + H 2 O.

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Section: Comparison Of the Simulated Results With The Experimental Datamentioning

confidence: 99%

Reaction Mechanism of Ethylene Oxide at Various Oxygen/Ethylene Oxide Ratios in an RF Cold Plasma Environment

Liao

Wei

Hsieh

et al. 2005

Aerosol Air Qual. Res.

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“…Spherical symmetry for the inner wind is assumed to calculate the shell volume and the total number of C 2 H 2 and C 6 H 6 molecules. We assume that the growth of C 6 H 6 to coronene, C 24 H 12 , proceeds through the H-abstraction-C 2 H 2 -addition (HACA) mechanism (Frenklach et al 1984) with the addition of nine C 2 H 2 molecules, and that once coronene forms, the growth of grains continues via C 24 H 12 dimerisation, coalescence, and coagulation (Cherchneff 2011b), We discard other growth mechanisms such as the polimerisation of polyynes on aromatic radical sites proposed by Krestinin et al (2000) because the abundances of C 4 H 2 are far too low to foster a significant growth of aromatic structures through this channel. Further growth via C 2 H 2 addition on the surface of grains may occur but is not considered in our simple estimate.…”

Section: Carbon Dust Precursors: Hydrocarbons and Aromaticsmentioning

confidence: 99%

The inner wind of IRC+10216 revisited: new exotic chemistry and diagnostic for dust condensation in carbon stars

Cherchneff

2012

A&A

118

133

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Aims. We model the chemistry of the inner wind of the carbon star IRC+10216 and consider the effects of periodic shocks induced by the stellar pulsation on the gas to follow the non-equilibrium chemistry in the shocked gas layers. We consider a very complete set of chemical families, including hydrocarbons and aromatics, hydrides, halogens, and phosphorous-bearing species. Our derived abundances are compared to those for the latest observational data from large surveys and the Herschel telescope. Methods. A semi-analytical formalism based on parameterised fluid equations is used to describe the gas density, velocity, and temperature from 1 R to 5 R . The chemistry is described using a chemical kinetic network of reactions and a set of stiff, ordinary, coupled differential equations is solved. Results. The shocks induce an active non-equilibrium chemistry in the dust formation zone of IRC+10216 where the collision destruction of CO in the post-shock gas triggers the formation of O-bearing species such as H 2 O and SiO. Most of the modelled molecular abundances agree very well with the latest values derived from Herschel data on IRC+10216. The hydrides form a family of abundant species that are expelled into the intermediate envelope. In particular, HF traps all the atomic fluorine in the dust formation zone. The halogens are also abundant and their chemistry is independent of the C/O ratio of the star. Therefore, HCl and other Cl-bearing species should also be present in the inner wind of O-rich AGB or supergiant stars. We identify a specific region ranging from 2.5 R to 4 R , where polycyclic aromatic hydrocarbons form and grow. The estimated carbon dust-to-gas mass ratio derived from the mass of aromatics formed ranges from 1.2 × 10 −3 to 5.8 × 10 −3 and agrees well with existing values deduced from observations. This aromatic formation region is situated outside hot layers where SiC 2 is produced as a bi-product of silicon carbide dust synthesis. The MgS grains can form from the gas phase but in lower quantities than those necessary to reproduce the strength of the 30 μm emission band. Finally, we predict that some molecular lines will show a flux variation with pulsation phase and time (e.g., H 2 O), while other species will not (e.g., CO). These variations merely reflect the non-equilibrium chemistry that destroys and reforms molecules over a pulsation period in the shocked gas of the dust formation zone.

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“…[33] Similar studies focused also on the formation of slightly larger systems (such as naphthalene [34,35], or indene [36,37]), or consider in general the mechanism of PAH growth. [38] Along this line, we have already considered [39] the first growth steps of aromatic systems through the ring closure-radical breeding polyyne-based mechanism proposed by Krestinin [40] (polyynes had already been considered at an earlier time by Homann and Wagner [41]). …”

Section: -Ring Closure In C3h3 +C4h2mentioning

confidence: 99%

First carbon ring closures started by the combustive radical addition of propargyl to butadiyne. A theoretical study

Maranzana¹,

Indarto²,

Ghigo³

et al. 2013

Combustion and Flame

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Detailed modeling of soot formation in hydrocarbon pyrolysis

Cited by 136 publications

References 21 publications

Reaction Mechanism of Ethylene Oxide at Various Oxygen/Ethylene Oxide Ratios in an RF Cold Plasma Environment

Reaction Mechanism of Ethylene Oxide at Various Oxygen/Ethylene Oxide Ratios in an RF Cold Plasma Environment

The inner wind of IRC+10216 revisited: new exotic chemistry and diagnostic for dust condensation in carbon stars

First carbon ring closures started by the combustive radical addition of propargyl to butadiyne. A theoretical study

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