Kinetic Modeling of the Free-Radical Process during the Initiated Thermal Cracking of Normal Alkanes with 1-Nitropropane as an Initiator

Guan, Yulei; Yang, Bolun; Qi, Suitao; Yi, Chunhai

doi:10.1021/ie200515g

Cited by 20 publications

(4 citation statements)

References 73 publications

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“…This is due to the scission of weak C–N bonds in the molecules to generate alkyl and amino radicals, which initiate fuel cracking at relatively low temperatures. Similarly, organic amines, including octadecylamine, tributylamine, triethylamine, and hyperbranched poly-(amidoamine) (CPAMAM), have been reported to be effective in enhancing the cracking of hydrocarbon fuels. ,,− It is noted that the promotion effect of ILs in our case is not as good as the previously reported organic amines, which could be ascribed to a low concentration of ILs and the robust imidazole ring.…”

Section: Resultscontrasting

confidence: 59%

“…Symmetrical imidazolium ionic liquids (ILs) have high thermal stability, high hydrocarbon solubility, and strong binding ability to metal nanoparticles. − In addition, the C–N in the imidazolium group would also initiate the cracking by providing radicals as alkylamines and hyperbranched CPAMAM polymer. ,,− Based on these, we propose to prepare hydrocarbon-soluble metal nanoparticles by using symmetrical imidazolium ionic liquids as protective agents in this work. The symmetric 1,3-bis(14-alkyl) imidazolium ionic liquid was chosen due to its conjugated imidazole ring with C–N bonds and symmetric long-chain alkyl groups at the 1st and 3rd positions (Figure ).…”

Section: Introductionmentioning

confidence: 99%

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Heat Sink Enhancement of Decalin by Symmetrical Imidazolium Ionic Liquid-Capped Metal Nanoparticles

Zhang¹,

Zhai²,

Wang³

et al. 2023

Energy Fuels

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Catalytic cracking−dehydrogenation of hydrocarbon fuels with hydrocarbon-soluble metal nanoparticles is an appealing way to improve fuel heat sink in a high-speed aircraft. In this work, two hydrocarbon-soluble metal nanoparticles (Pd@ILs and Pt@ILs) by using symmetrical imidazolium ionic liquids (1,3-bis(14-alkyl) imidazolium bromide) as protective agents were successfully synthesized. The catalytic performance for cracking and dehydrogenation of decalin-based nanofluids was investigated using an electrically heated tubular reactor. In comparison with Pd@14N with the conventional tetradecylamine ligand, Pd@ILs and Pt@ILs catalysts exhibited smaller average particle sizes and showed better performance in terms of dispersion stability, thermal stability, and catalytic activity. Fourier transform infrared (FT-IR) and density functional theory (DFT) calculations demonstrated that the strong affinity of C atoms in the conjugate imidazole ring to the metal surface allows these nanoparticles to be stably dispersed in decalin for at least 2 months. In the quasi-homogeneous conversion of decalin, Pd@ILs exhibited the best performance in promoting fuel cracking and dehydrogenation conversion with the highest yields of hydrogen and unsaturated hydrocarbon products, especially aromatic products, thus enhancing the heat sink of nanofluids. Particularly, the heat sink of nanofluids with the Pd@ILs catalyst was 3.39 MJ kg −1 at 700 °C, which was 0.58 MJ kg −1 higher than that from decalin thermal cracking and 0.43 MJ kg −1 higher than that of the nanofluids with the Pd@14N catalyst. In addition, Pd@ILs nanofluids gave the highest heat sink of 3.61 MJ kg −1 at 725 °C. The significant enhancements are attributed to cooperative interplay between the initiation effect of ILs and the remarkable catalytic ability of Pd nanoparticles in cracking−dehydrogenation reaction, as well as the unique properties of Pd@ILs, including smaller Pd particle size, more accessible surface Pd active sites, and higher thermal stability. This work shows that symmetrical imidazolium ionic liquid-capped metal nanoparticles can serve as effective quasi-homogeneous catalysts for enhancing heat sink of hydrocarbon fuels through catalytic cracking and dehydrogenation.

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Section: Resultscontrasting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Heat Sink Enhancement of Decalin by Symmetrical Imidazolium Ionic Liquid-Capped Metal Nanoparticles

Zhang¹,

Zhai²,

Wang³

et al. 2023

Energy Fuels

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show abstract

“…The satisfactory model prediction of the experimental measurements allowed the kinetic effect of nitromethane initiation on n -decane pyrolysis to be analyzed. Guan et al , explored the effect of nitroalkane initiators on the cracking of C7 alkanes using quantum chemical calculations and reactive molecular dynamics simulations, respectively. Reasonable Arrhenius parameters estimated from reactive molecular dynamics simulations compared well with the experimental results.…”

Section: Introductionmentioning

confidence: 99%

Low-Temperature-Initiated Cracking of Hydrocarbons to Produce Olefins: Simulation and Comparison of Different Initiators

Ren,

Mao,

Shen

et al. 2024

Ind. Eng. Chem. Res.

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Low-temperature-initiated cracking technology has significant potential to develop new hydrocarbon pyrolysis with better atomic economy and higher yields of light olefins. The impacts of three representative initiators, triethylamine (TEA), nitromethane (NM), and di-tert-butyl peroxide (DTBP), were compared. Sufficiently detailed co-cracking reaction networks of three initiators with n-hexane were obtained through an automatic reaction network generator RMG, and the corresponding steam cracking tubular reactor simulation was performed. The results showed that the initiator with a lower cracking temperature brought about a more noticeable decrease in the cracking temperature of n-hexane. Both TEA and NM increased the carbon atom conversion from n-hexane to ethylene and propylene, especially propylene. NM was more significant, while DTBP was almost ineffective. Through kinetic parameter analysis, it was found that the temperature dependence of the key reaction caused different initiator performance. NM completely cracked at an appropriate temperature where the rate constants of the hydrogen abstraction and ethylene generation had reached a high level, and the released free radicals were effective. Visual reaction network analysis revealed that NM had a strong ability to release free radicals, and these free radicals significantly adjusted the competitive reaction path to produce ethylene and propylene, resulting in the most obvious effect on improving the conversion of n-hexane and the yield of propylene. The action laws of NM described above under hydrocarbon pyrolysis conditions indicate that NM may be the most suitable initiator for low-temperature-initiated cracking of hydrocarbons among these three initiator types.

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“…Chakraborty et al 24 found that the added initiator had an effect when the fuel pyrolysis rate was low, and its effect was negligible when the fuel pyrolysis rate was high. Guan et al 26,27 studied the initial pyrolysis path of n-alkane/nitro-alkane-initiated pyrolysis by the quantum chemical calculation method and obtained four possible initial reactions according to the calculation results of activation energy. In summary, the previous research on initiated pyrolysis focuses on macroscopic aspects such as improving the fuel pyrolysis rate and heat sink.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Modeling Investigation on the Pyrolysis of n-Decane Initiated by Nitropropane. Part I: 1-Nitropropane

et al. 2023

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Initiators can accelerate the pyrolysis of hydrocarbon fuels, thereby reducing the required reaction temperature in the hypersonic vehicle heat exchanger/reactor. Nitro-alkanes are considered as efficient initiators due to their lower energy barrier of the C–N bond cleavage reaction. To research the mechanism of the initiation effect of nitro-alkanes on the decomposition of hydrocarbon fuel, synchrotron radiation vacuum ultraviolet photoionization-mass spectrometry (SVUV-PIMS) was employed to experimentally study the pyrolysis of n-C10H22, 1-C3H7NO2, and their binary mixtures in a flow tube under pressures of 30 and 760 Torr. The species identified and measured in the experiments included alkanes, alkenes, dialkenes, alkynes, nitrogen oxides, benzene, and free radicals, which revealed the mechanism of n-decane and 1-C3H7NO2 pyrolysis, as well as the interactions of the two fuels. Experiments show that the presence of 1-C3H7NO2 reduces the initial decomposition temperature of n-C10H22, and the increased pressures could achieve a stronger promoting effect on the conversion of n-C10H22. A detailed kinetic model containing 1769 reactions and 278 species was established and validated based on the mole fraction distributions of n-C10H22, major pyrolysis species, and important intermediates measured in pure fuel and initiated pyrolysis. The kinetic model can accurately predict the experimental data, and the mechanism of 1-C3H7NO2-initiated pyrolysis of n-C10H22 is analyzed with the model. The effect of 1-C3H7NO2 on the consumption of n-C10H22 and selectivity of cracked products is highlighted.

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Kinetic Modeling of the Free-Radical Process during the Initiated Thermal Cracking of Normal Alkanes with 1-Nitropropane as an Initiator

Cited by 20 publications

References 73 publications

Heat Sink Enhancement of Decalin by Symmetrical Imidazolium Ionic Liquid-Capped Metal Nanoparticles

Heat Sink Enhancement of Decalin by Symmetrical Imidazolium Ionic Liquid-Capped Metal Nanoparticles

Low-Temperature-Initiated Cracking of Hydrocarbons to Produce Olefins: Simulation and Comparison of Different Initiators

Experimental and Modeling Investigation on the Pyrolysis of n-Decane Initiated by Nitropropane. Part I: 1-Nitropropane

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