TEMPO-Assisted Thermal and Catalytic Cracking of 3-Carene and JP-10 to Produce Low-Molecular-Weight Hydrocarbons

Abstract

This study investigates the effect of combining a free-radical initiator, TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy), and a zeolite catalyst (HY) on the pyrolysis of JP-10 (exotetrahydrodicyclopentadiene) and 3-carene (3,7,7-trimethylbicyclo [4.1.0] hept-3-ene) for their use as endothermic hydrocarbon fuels. Analytical fast pyrolysis experiments were conducted at 445, 590, and 764 °C in a curie point pyrolyzer hyphenated with a gas chromatograph/mass spectrometer. The experiments explored different cracking methods: noncatalytic pyrolysis, free-radical initiator-assisted pyrolysis, zeolite (HY)-assisted pyrolysis, and a combined approach using both HY zeolite and TEMPO, for the pyrolysis of JP-10 and 3-carene. The results demonstrate that the combination of TEMPO and HY enhances the yield of low-molecular-weight (LMW) hydrocarbons compared to thermal cracking or cracking with either initiator or zeolite alone, especially at a low temperature. For JP-10, the TEMPO + HY-assisted cracking at 445 °C resulted in a combined LMW alkane and alkene yield of 19%, which is considerably higher than that achieved with HY-assisted cracking (14%) and TEMPO-assisted cracking (2%). Similarly, the TEMPO + HY-assisted pyrolysis of 3-carene at 445 °C produced ∼17% yield of LMW hydrocarbons, which was higher than the yields achieved using either TEMPO alone (1%) or HY alone (12%). Plausible free-radical reactions were proposed based on the detected products. The findings suggest that TEMPO can be an effective additive for enhancing the yield of LMW hydrocarbons from jet fuels for endothermic fuel applications.