Thermal Decomposition Kinetics and Mechanism of 1,1′-Bicyclohexyl

Abstract

Thermal decomposition of 1,1′-bicyclohexyl, a potential surrogate component of high-density hydrocarbon fuels, was performed in a batch-type reactor to investigate its thermal stability. A first-order kinetic equation is supposed to correlate the decomposition process, and the apparent rate constants, ranging from 0.0223 h −1 at 683 K to 0.1979 h −1 at 713 K, are determined. The Arrhenius parameters are determined with the pre-exponential factor A = 6.22 × 10 20 h −1 and the activation energy E a = 293 kJ·mol −1 . Compared with four typical hydrocarbon compounds, the thermal stability trend is observed in the order of n-dodecane ≈ 1,3,5-triisopropylcyclohexane > bicyclohexyl > n-propylcyclohexane > decalin. Cyclohexane and cyclohexene are found to be the primary products due to the relatively low energy of the C−C bond connecting the two cyclohexyl rings. Bicyclohexyl decomposes into cyclohexane and cyclohexene equivalently at the beginning of the reaction. A probable mechanism on the basis of quantum calculation and GC-MS analyses for the decomposition of bicyclohexyl is proposed to explain the product distribution. It is shown that the formation of decomposition products is mainly obtained through hydrogen transfer, β-scission, isomerization, or dehydrogenation.

Thermal Decomposition and Kinetics of a High-Energy-Density Hydrocarbon Fuel: Tetrahydrotricyclopentadiene (THTCPD)

“…The experimental activation energy of thermal decomposition of JP-10 in the literature was 256.4 kJ mol –1 (in a batch reactor) and 261.1 kJ mol –1 (in a flow reactor). , In comparison to the result of 248.5 kJ mol –1 in this study, it suggests that THTCPD is slightly less stable than JP-10. Except for the difference in the carbon number with a similar structure, it also can be explained that THTCPD has eight tertiary carbons, while JP-10 has six tertiary carbons. − …”

Densities and Viscosities of Ternary System n-Dodecane (1) + Bicyclohexyl (2) + n-Butanol (3) and Corresponding Binaries at T = (293.15 to 333.15) K

“…It is an ideal model compound to research the properties of fuels. Bicyclohexyl has high density and good thermal stability, which is usually found in coal-derived fuels. − In consideration of similar molecular structure to decalin and with same carbon number as n -dodecane, bicyclohexyl has potential to become a surrogate component of jet fuels. − N -Butanol is widely used as fuel additive to enhance the octane rating of fuel, improve fuel burning characteristics, and reduce atmospheric pollution . In addition, n -butanol is a kind of bioenergy alternative to petroleum and has a chance to promote the combustion process of hydrocarbon fuel as additive. , Hence, detailed data of physical properties for the ternary system n -dodecane + bicyclohexyl + n -butanol can provide guidance for the research of jet fuels.…”

New Insights on the Kinetic Analysis of Isothermal Data: The Independence of the Activation Energy from the Assumed Kinetic Model

“…1−14 The experimental data are usually collected under isothermal or linear heating conditions. While linear heating rate experiments provide quickness and simplicity, in many studies, such as those involving long-term aging at operation temperatures, 15−17 oxidation processes, 18−20 reaction progress followed by spectral or DRX peak intensity measurements, 21−23 chemical looping processes 1,3,11,24 or those setups that try to replicate industrial operation conditions, 9,12,13 isothermal experiments are still the most convenient or even feasible option. Moreover, isothermal experiments present the distinct advantage of a higher capability for kinetic mechanism discrimination because of the fact that the shape of the integral α−time curve is directly related to the obeyed model.…”

“…Kinetic analysis is widely employed as a tool for obtaining the essential knowledge needed for modeling processes on an industrial scale. This is also true in the field of energy conversion and production, with an important number of papers published every year in which the main objective is determining the kinetics governing processes, such as pyrolysis, gasification, combustion, or thermal decomposition, to optimize operating conditions. − The experimental data are usually collected under isothermal or linear heating conditions. While linear heating rate experiments provide quickness and simplicity, in many studies, such as those involving long-term aging at operation temperatures, − oxidation processes, − reaction progress followed by spectral or DRX peak intensity measurements, − chemical looping processes ,,, or those setups that try to replicate industrial operation conditions, ,, isothermal experiments are still the most convenient or even feasible option.…”

“…This is also true in the field of energy conversion and production, with an important number of papers published every year in which the main objective is determining the kinetics governing processes, such as pyrolysis, gasification, combustion, or thermal decomposition, to optimize operating conditions. − The experimental data are usually collected under isothermal or linear heating conditions. While linear heating rate experiments provide quickness and simplicity, in many studies, such as those involving long-term aging at operation temperatures, − oxidation processes, − reaction progress followed by spectral or DRX peak intensity measurements, − chemical looping processes ,,, or those setups that try to replicate industrial operation conditions, ,, isothermal experiments are still the most convenient or even feasible option. Moreover, isothermal experiments present the distinct advantage of a higher capability for kinetic mechanism discrimination because of the fact that the shape of the integral α–time curve is directly related to the obeyed model. , Thus, the α–time traces of phase-boundary-controlled reactions (so-called “ n -order” reactions) are convex; diffusion-controlled reactions are concave; and those whose rate is controlled by the formation and growth of nuclei (Avrami–Erofeev models) have a sigmoidal shape.…”