TEMPO-Assisted\nThermal and Catalytic Cracking of 3‑Carene\nand JP-10 to Produce Low-Molecular-Weight Hydrocarbons

This\nstudy investigates the effect of combining a free-radical\ninitiator, TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy), and a zeolite\ncatalyst (HY) on the pyrolysis of JP-10 (exotetrahydrodicyclopentadiene)\nand 3-carene (3,7,7-trimethylbicyclo [4.1.0] hept-3-ene) for their\nuse as endothermic hydrocarbon fuels. Analytical fast pyrolysis experiments\nwere conducted at 445, 590, and 764 °C in a curie point pyrolyzer\nhyphenated with a gas chromatograph/mass spectrometer. The experiments\nexplored different cracking methods: noncatalytic pyrolysis, free-radical\ninitiator-assisted pyrolysis, zeolite (HY)-assisted pyrolysis, and\na combined approach using both HY zeolite and TEMPO, for the pyrolysis\nof JP-10 and 3-carene. The results demonstrate that the combination\nof TEMPO and HY enhances the yield of low-molecular-weight (LMW) hydrocarbons\ncompared to thermal cracking or cracking with either initiator or\nzeolite alone, especially at a low temperature. For JP-10, the TEMPO\n+ HY-assisted cracking at 445 °C resulted in a combined LMW alkane\nand alkene yield of 19%, which is considerably higher than that achieved\nwith HY-assisted cracking (14%) and TEMPO-assisted cracking (2%).\nSimilarly, the TEMPO + HY-assisted pyrolysis of 3-carene at 445 °C\nproduced ∼17% yield of LMW hydrocarbons, which was higher than\nthe yields achieved using either TEMPO alone (1%) or HY alone (12%).\nPlausible free-radical reactions were proposed based on the detected\nproducts. The findings suggest that TEMPO can be an effective additive\nfor enhancing the yield of LMW hydrocarbons from jet fuels for endothermic\nfuel applications.