Experimental study on oxidation-chemistry of iso-propanol and tetrahydrofuran blends using a jet-stirred reactor

Decarbonizing the aviation sector is crucial for meeting global climate goals, with a strong emphasis on reducing emissions from long-range flights where liquid fuels are indispensable. Synthetic fuels or e-fuels have emerged as a promising solution for sustainable aviation. This study explores the oxidation chemistry of fuel blends consisting of iso-propanol and tetrahydrofuran (THF), two liquid e-fuels that show potential for use in energy-efficient aviation. By utilizing a jet-stirred reactor (JSR) coupled with a Time-of-Flight Mass Spectrometer (TOF-MS), the study examines the oxidation behavior of these fuels, both individually and in blends, under controlled temperature and pressure conditions. Experiments were conducted over a temperature range of 500 to 1200 K, at a pressure of 1 bar, and with lean fuel-air mixtures (ϕ = 0.5). These conditions are typical for lean premixed pre-vaporized (LPP) combustion systems, commonly used in gas turbines to lower NO_x and soot emissions. The results highlight a critical reactivity threshold for THF at low temperatures, below which its oxidation ceased, particularly at mole fractions <0.0035. The presence of iso-propanol in the blends further influenced the oxidation behavior: at low temperatures, iso-propanol suppressed THF’s reactivity by forming stable acetone. In contrast, at higher temperatures, iso-propanol enhanced overall reactivity by promoting radical formation, converting acetone to ketene, and facilitating significant propene production through primary isopropyl radical channels. This study reveals the intricate chemical interactions between iso-propanol and THF, offering critical insights into their oxidation mechanisms, with a particular focus on the low-temperature reactivity pathways of iso-propanol.

Novelty and significance statement: This study explores the testing of novel fuels for Lean Premixed Pre-vaporized (LPP) combustion, focusing on the oxidation chemistry of iso-propanol and tetrahydrofuran (THF) as alternative fuels. The research examines the low-temperature reactivity of iso-propanol and THF, both individually and in blends, using a Jet-Stirred Reactor (JSR). Notably, it provides the first detailed low temperature analysis of iso-propanol’s reactivity without the addition of oxidizers like O₃. The study reveals unique suppression mechanisms and temperature-dependent shifts in reaction pathways when the fuels are blended. Through experimental testing and kinetic modeling, the research refines predictive existing models, advancing the understanding of these fuels for cleaner and more efficient combustion applications.