The high temperature pyrolysis of 1,3‐butadiene: heat of formation and rate of dissociation of vinyl radical

Kiefer, J. H.; Wei, H. C.; Kern, R. D.; Wu, C. H.

doi:10.1002/kin.550170208

Cited by 80 publications

(48 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the present work, the lower value obtained by ab initio calculations of Ayrancy and Back [30] was used. This value was also confirmed by Kiefer et al [31].At lower conversions, propane is formed by the reaction:2-C3H,.+ RH + C3H, + R . (8) whereas, at high conversions and high temperatures (1000 K), a considerable amount is formed in the recombination reaction:…”

supporting

confidence: 81%

Thermal decomposition of 2, 3‐dimethyl butane: Experiments and mechanistic modelling

Stabel¹,

Hönig²,

Nowak³

et al. 1990

Chem Eng & Technol

View full text Add to dashboard Cite

Pyrolysis of 2,3-dimethyl butane (DMB) was carried out in a quartz flow reactor in the temperature range from 740 to 1032 K at normal pressure. The input concentration of DMB was 3.3 x mol/l using argon as diluent. Reaction time ranged between 3.1 and 3.9 s. The following products were analyzed by two-column gas chromatography: hydrogen, methane, ethene, propane, propene, butenes, butadiene, 2-methyl-2-butene, isoprene, benzene and toluene. Compared to thermal decomposition of n-hexane under similar experimental conditions, the main difference concerned the formation of ethylene, ethane and branched alkanes. A reaction model, based on elementary reactions, was developed to predict the experimental results and to verify our data basis of elementary reactions under different conditions. The model gives a quantitative description of the complex chemistry of the process. In addition, an algorithm is presented for model reduction. IntroductionThermal cracking of light naphtha feedstock is the most important process for producing olefins and diolefins. Production processes and equipment are designed on a purely empirical basis, mainly because a more profound knowledge of what happens on the molecular level is lacking. In this field, mechanistic modelling could help to predict, at least approximately, the reaction rates and product distribution of the complex chemical reaction system including its dynamics [32].In previous work [Z, 111, models were developed for the thermal degradation of n-hexane as an example of linear hydrocarbons. Up to 600 elementary reactions (ER) were needed to describe reaction rates and the formation of products up to high conversions. Moreover, with this model, the experimental results of pyrolysis of alkenes and n-hexane mixtures could be predicted. The experiments were carried out to investigate inhibition and acceleration effects on the overall reaction. This contribution presents an investigation on the pyrolysis of branched hydrocarbons. As a model substance, 2,3-dimethyl butane was used to investigate the influence of branched chain structures on decomposition. It was expected that, compared to nhexane, the decay mechanism of DMB would be less complex. Another aim was to test parts of our data basis of elementary reactions under conditions where C,-hydrocarbons are less important.It is generally accepted that thermal decomposition of hydrocarbons follows a radical reaction mechanism according to the Rice-Herzfeld scheme. The work of Niclause and Martin shows clearly that molecular reaction steps are of no importance whatsoever in thermal cracking [S, 61. Today, ESR and MS offer analytical tools to identify radical intermediates resulting from homolytic dissociation of C-C and C-H bonds. Capillary gas chromatography has reached a standard of development such that stable intermediate products can be quantitatively evaluated even in very small quantities 1261. Therefore, more and more precise experimental data become available which can be used for the development and verification of reacti...

show abstract

supporting

confidence: 81%

Thermal decomposition of 2, 3‐dimethyl butane: Experiments and mechanistic modelling

Stabel¹,

Hönig²,

Nowak³

et al. 1990

Chem Eng & Technol

View full text Add to dashboard Cite

show abstract

“…No account was taken of pressure dependencies. The rate constants for the direct ethylene and acetylene formation route are considerably smaller than the results of Skinner and Sokolski [12] and to a lesser degree the adjusted laser schlieren results of Kiefer et al [9,10]. Finally, Thorn et al [17] carried out vinyl radical combination studies and postulated cyclobutene as a product.…”

Section: Past Workmentioning

confidence: 88%

“…The chief issue is the question of reaction mechanism. Kiefer and coworkers [9,10] measured rates of decomposition using the laser schlieren and laser flash-absorption method. Due to the short time available for reaction, these are the most unambiguous experimental observations in terms of accessing initial processes.…”

Section: Master Equation Treatmentmentioning

confidence: 99%

“…The uncertainty is on the nature of this process. Kiefer and coworkers [9] assumed that the decomposition to two vinyl radicals is the primary reaction step. They obtained a value for the heat of formation of vinyl radicals that is now known to be much too low [11].…”

Section: Master Equation Treatmentmentioning

confidence: 99%

“…They carried out shock tube experiments at high dilutions under pressure and temperature conditions similar to those used by Kiefer et al [9] in their laser schlieren studies. The rates of hydrogenatom production were at least two orders of magnitude lower than the rate constant for butadiene decomposition determined by Kiefer et al [9].…”

Section: Past Workmentioning

confidence: 99%

See 2 more Smart Citations