Experimental Characterization of Tetrahydrofuran Low-Temperature Oxidation Products Including Ketohydroperoxides and Highly Oxygenated Molecules

The oxidation of tetrahydrofuran (THF) was carried out in a continuously jet-stirred tank reactor at a total pressure of 10 atm, in fuel-lean conditions (equivalence ratio = 0.5), at an initial fuel mole fraction of 5000 ppm, at a mean residence time of 2 s, and for temperatures ranging from 550 to 620 K. High-resolution mass spectrometry analyses were used to characterize low-temperature oxidation products of THF. Mass spectrometry analyses were performed using atmospheric pressure chemical ionizations in positive and negative modes. Both flow injection analyses and ultrahigh-pressure liquid chromatography-tandem mass spectrometry allowed for characterization of a large set of chemicals, including hydroperoxides and diols (C4H8O3), ketohydroperoxides (C4H6O4), and more oxygenated molecules (up to C4H8O7), resulting in the addition of up to three oxygen molecules on alpha and beta THF radicals. The existence of -OH or -OOH groups in the products was confirmed by hydrogen-deuterium exchange using D2O. We detected 24 products with a molecular weight of 40-168 not reported in previous studies. Simulations using the latest THF oxidation chemical kinetic reaction mechanism available from the literature were compared to the present measurements of ketohydroperoxides and other products of THF cool flames. The kinetic scheme represented well the present qualitative data.

Automated summary

The oxidation of tetrahydrofuran (THF) was studied under high pressure conditions, with analyses revealing 24 previously unreported products. The chemical kinetic reaction mechanism of THF oxidation was found to qualitatively match experimental data.