Experimental and theoretical study of cyclopropanated fuel exo,exo-Tetracyclo[3.3.1.02,4.06,8]nonane pyrolysis in a jet-stirred reactor

Abstract

Exo,exo-Tetracyclo[3.3.1.02,4.06,8]nonane (exo-TCN), a kind of cyclopropanated fuel with high tension three-membered ring, which has the characteristics of high density, high net heat of combustion and good low-temperature performance, is a potential high-energy-density liquid fuel. To deeply understand its combustion behavior, and lay a foundation for practical application, detailed experimental and theoretical study is necessary. The pyrolysis of exo-TCN was investigated in a jet-stirred reactor at a temperature range of 500–1010 K under atmospheric pressure with a residence time of 2 s. 54 products and intermediates ranging from m/z = 2–204 were identified and quantified by synchrotron vacuum ultraviolet photoionization mass spectrometry and online gas chromatography, the major products were hydrogen, ethylene, benzene, methane, propene, toluene and styrene. The potential energy surfaces of exo-TCN unimolecular decomposition reactions were calculated by quantum chemistry at CBS-QB3 level. It is found that the pyrolysis of exo-TCN experiences three stages. In the first stage, exo-TCN isomerizes into Tricyclo[3.3.1.02,4]non-6-ene (TCN-6) by ring expansion of the three-membered ring. In the second stage, TCN-6 generates two main isomers through ring expansion reactions, and decomposes into pyrolysis products. The third stage is the secondary reaction of the intermediate products. Finally, combined with the experimental results and theoretical calculation, the possible reaction mechanism of exo-TCN pyrolysis was proposed, and the related reaction rate constants were calculated.