# Low temperature oxidation of neo-pentanal – Detailed speciation and kinetic modelling

Zeynep Serinyel, Bakr Hoblos, Guillaume Dayma, Philippe Dagaut

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Zeynep Serinyel, Bakr Hoblos, Guillaume Dayma, Philippe Dagaut. Low temperature oxidation of neo-pentanal – Detailed speciation and kinetic modelling. 13th International Conference on Chemical Kinetics, Lawrence Berkeley National Laboratory, Jun 2025, Tahoe City, California, United States. hal-05109368

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Submitted on 12 Jun 2025

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Chemical Kinetics for a
Sustainable Future

Book of Abstracts

13th International Conference on Chemical Kinetics

June 8th-13th, 2025

Granlibakken Tahoe Resort in Tahoe City, California
# Low temperature oxidation of neo-pentanal – Detailed speciation and kinetic modelling

Zeynep Serinyel,ª,b Bakr Hoblos,ª,b Guillaume Dayma,ª,b and Philippe Dagautb

ªUniversité d'Orléans, avenue du Parc Floral, 45100 Orléans, FRANCE

ᵇCNRS-ICARE, 1C avenue de la Recherche Scientifique 45100 Orléans, France
(zeynep.serinyel@cnrs-orleans.fr)

Neo-pentanal (2,2-Dimethylpropanal) is a highly branched C₅ aldehyde, which has not been studied before for its oxidation kinetics. This study provides a detailed speciation of neo-pentanal oxidation between 600 and 1200 K. The experiments were done in a jet-stirred reactor at a constant residence time of 0.7 s and at 10 atm. A fuel-lean (φ = 0.5), a stoichiometric and a fuel-rich mixture (φ = 2) with an initial fuel mole fraction of 0.1% were tested. A fourth mixture with an initial fuel mole fraction of 0.3% was also tested at a higher residence time of 1.5 s. The former experimental conditions are the same as in our previous studies on n-pentanal [1] and 2- and 3-methylbutanal [2], while the latter condition is chosen in order to trigger reactivity at lower temperatures.

As opposed to our previous studies on C₅ aldehydes [1, 2], no low-temperature reactivity is observed even with the leanest mixture. However, two sharp conversion regions are observed, centered around 790 K and 970 K. The mixture with higher fuel content and higher residence time starts reacting around 600 K and is consumed steadily as a function of the temperature, showing no NTC behavior.

Oxidation behavior of the first three mixtures were compared to n-pentanal, 2-methylbutanal and 3-methylbutanal and is shown in Fig 1 for the oxidation of the lean mixture. Neo-pentanal, as expected, is by far the least reactive among its C₅ peers, full conversion is also reached at much higher temperatures.

The main hydrocarbon intermediates in neo-pentanal oxidation are methane, ethylene, propene and iso-butene. Trace amounts of iso-butanal were also quantified for mixtures with 0.1 % fuel going high as 25 ppm for the 0.3% mixture.

A kinetic sub-mechanism is also developed in this study. Neo-pentanal is found to be governed by the fate of the *tert*-butyl radicals, as is the case with aldehydes and their corresponding alkyl radicals. The structure of *tert*-butyl radicals, however, does not allow the formation of a carbonyl hydroperoxide as opposed to the reactive nature of *n*-butyl, *sec*-butyl or even *iso*-butyl radicals [1, 2].

<figure><img src="image_2.png" /><figcaption>**Figure 1.** Fuel conversion as a function of reactor temperature, experimental conditions: φ = 0.5, τ = 0.7 s, p = 10 atm. Black, blue and red data are from previous work [1, 2].</figcaption></figure>

## References

[1] Z. Serinyel, G. Dayma and P. Dagaut, *Proc. Comb. Inst.*, 40(1), 105254 (2024).

[2] Z. Serinyel, C. Togbé, G. Dayma and P. Dagaut, *Energy & Fuels*, 31(3), 3206-3218 (2014).