Thermal Stability and Decomposition Kinetics of 1,3-Dimethyladamantane

Abstract

For a comprehensive understanding of the properties of 1,3-dimethyladamantane (1,3-DMA) as a candidate of high energy-density hydrocarbon fuels, thermal stability of 1,3-DMA under different conditions is investigated. The thermal decomposition kinetics in the batch reactor between 693 and 743 K has been determined, with the rate constants ranging from 4.00 × 10–7 s–1 at 693 K to 35.19 × 10–7 s–1 at 743 K, along with the Arrhenius parameters of A = 2.39 × 107 s–1 and activation energy E a = 183 kJ·mol–1. The rate constants for the thermal decomposition of 1,3-DMA are observed to be smaller than those of some typical model fuels, decalin, propylcyclohexane, butylcylohexane, and n-dodecane, demonstrating that the thermal stability of 1,3-DMA is satisfactory. The thermal decomposition of 1,3-DMA in the flowing reactor at temperatures from 873 to 973 K and pressures from 0.1 to 5.0 MPa is further performed. It can be observed that the conversion of 1,3-DMA and the yield of gaseous products increase clearly with the rise of temperature or pressure. The residence time is the main factor for the change of decomposition depth. Methane and hydrogen are the major gaseous products that are produced through demethylation and dehydrogenation. In the liquid residues, toluene and xylene are observed and quantified by GC-MS, HPLC, and NMR as the main aromatics produced. On the basis of component analysis, a hypothetical mechanism of thermal decomposition of 1,3-DMA is proposed to explain the product distribution. It is shown that the different products are mainly obtained through a combination of isomerization, hydrogen transfer, β-scission, and dehydrogenation. The results are expected to provide experimental information for the search of new high energy-density hydrocarbon fuels.

Molecular Design and Characterization of High-Cetane Alkyl Diamondoid Fuels

“…10 Ionic liquids were also investigated for the isomerization of tetrahydrotricyclopentadiene to generate a fuel mixture comprised mainly of C 15 H 24 adamantane and diamantane hydrocarbons with a reported density of 1.01 g/mL and a freezing point of −70 °C. 11 The thermal stability and decomposition pathway of 1,3-dimethyladamantane (DMA) has been studied, 12 while the densities, viscosities, refractive indices, and surface tensions of mixtures of DMA, 1ethyladamantane, and 1,3,5-trimethyladamantane with 1heptanol and cyclohexylmethanol have recently been measured. 13 Although adamantane is a natural and easily modified scaffold for high-density fuels, incorporation of a straight hydrocarbon chain would be required to both decrease the freezing point of the fuel and ideally increase the cetane number to >40.…”

Density, Viscosity, and Refractive Index for Binary Mixtures of Three Adamantane Derivatives with n-Nonane or n-Undecane at T = 293.15–343.15 K and Atmospheric Pressure

“…1,3-Dimethyladamantane (1,3-DMA), which is an alkyl derivative of adamantanes, has satisfying density and good thermal stability. , 1,3-DMA even shows higher thermal stability than JP-10 (used by U.S. Navy and Air Force), which has been considered as a new candidate of high-energy-density fuels or energetic additives for conventional fuels . 1,3,5-Trimethyladamantane (1,3,5-TMA) and 1-ethyladamantane (1-EA) are the homologous compounds of 1,3-DMA, and they also have a significantly low viscosity and freezing point .…”

Density and Viscosity of Ternary Mixture of Cyclopentanol + exo-Tetrahydrodicyclopentadiene + 1,3-Dimethyladamantane

“…Adamantine is a potential high-density hydrocarbon fuel with a high volumetric energy. As an alkyl derivative of adamantine, 1,3-dimethyladamantane (1,3-DMA, shown in Figure a) has a lower melting point and can promote the dissolution of additives in the liquid form. , exo -Tetrahydrodicyclopentadiene (JP-10, shown in Figure b), also called exo -tricyclo­[5.2.1.0 2,6 ]­decane, is suitable to serve as a single-component fuel for certain propellant applications on account of its specific impulse, high thermal stability, and widespread availability. − However, the thermal decomposition and initiation reaction performance of this kind of hydrocarbon fuel can be improved. Adding oxygenated additives to the fuel has been proved to be an effective way to adjust its physical properties along with reducing the emissions. − Cyclopentanol (Figure c), an additive candidate, tends to have a potential of improving the combustion process and reducing soot as well as particulate emission .…”

“…As an alkyl derivative of adamantine, 1,3dimethyladamantane (1,3-DMA, shown in Figure 1a) has a lower melting point and can promote the dissolution of additives in the liquid form. 3,4 exo-Tetrahydrodicyclopentadiene (JP-10, shown in Figure 1b), also called exo-tricyclo[5.2.1.0 2,6 ]decane, is suitable to serve as a single-component fuel for certain propellant applications on account of its specific impulse, high thermal stability, and widespread availability. 5−11 However, the thermal decomposition and initiation reaction performance of this kind of hydrocarbon fuel can be improved.…”