Isopropylcyclohexane pyrolysis at high pressure and temperature: Part 2. Experiment and simulation

Abstract

Pyrolysis of isopropylcyclohexane (IPCH), which is part of some transportation fuels, has been investigated at the temperature range of 923–1526 K and pressure of 9.8–20.2 bar. Mole fraction profiles of 27 products were obtained using gas-chromatography (GC) coupled to flame ionization detector (FID). A GC–MS has been used for identification of all the products as well. At high temperature ethene is the most abundant product followed by acetylene. Benzene is the most abundant aromatic product followed by toluene as the 2nd most abundant aromatic. Detailed kinetic model comprising of 426 species and 1354 reactions has been developed which shows a reasonable agreement with the experimental data. This has been aided by detailed ab initio calculations of reaction profiles and TST/VTST calculations of rate parameters reported in Part 1 of this work. Rate of production (ROP) analysis reveals that unimolecular decomposition of IPCH (C3H7 elimination and CH3 elimination) as well as H-abstraction reaction of IPCH are responsible for IPCH consumption. Sensitivity analysis reveals that C3H7 elimination channel is the most sensitive reaction for the consumption of IPCH. On the other hand, cyclohexyl radical (cC6H11) plays a critical role in the formation of aromatic products (as revealed by sensitivity analysis). Its β-C–H scission process (cC6H11 = cC6H10 + H) has positive effect on aromatic formation, while its isomerization via ring-opening (cC6H11 = P6XC6H11–1E) has negative effect on aromatic formation. The overall rate constant for IPCH decomposition has been found to be:(s−1)=108.16±0.25exp(−34.6±1.5/kcalmol−1)RTThese results could aid in our understanding of the unimolecular decomposition of IPCH as well as the aromatic products formation reaction pathways from IPCH and other similar hydrocarbons, which will eventually help us to understand better the combustion process of transportation fuels.