Chemical Study Of A Low-pressure Premixed Laminar 2-methylfuran Flame

Chemical structure of a low-pressure premixed laminar 2-methylfuran/oxygen/ argon flame with an equivalence ratio of 0.8 has been investigated by using tunable synchrotron vacuum ultraviolet photoionization and molecular-beam mass spectrometry. Photoionization mass spectra of 2-methylfuran/oxygen/argon flame were recorded as well as the photoionization efficiency curves of the combustion intermediates. Ionization energies of the combustion intermediates have been identified from the photoionization efficiency curves. The combustion intermediates are identified by comparing the measured ionization energies with those reported in literatures or those calculated with the method of ab initio. Possible reaction pathways of 2-methylfuran and its primary combustion derivatives are proposed based on the intermediates identified. The reaction pathways of 2-methylfuran has been compared with those of 2,5-dimethylfuran and furan reported in literature.A series of combustion intermediates have been detected in the 2-methylfuran/ oxygen/argon flame, including the primary combustion intermediates of 2-methylfuran. Possible reaction pathways of 2-methylfuran are proposed. The results indicate that 2-methylfuran can be consumed by hydrogen abstraction reaction. The H atom on the methyl in 2-methylfuran is easily abstracted by the radicals in flame to yield 2-furylmethyl. 2-Furylmethyl can be consumed by oxidation and ring-rupture reactions. It can also combine with other radicals in the flame to form higher furan derivatives. 2-Methylfuran, 2,5-dimethylfuran, and furan, can be consumed by H-abstraction and pyrolysis reactions. Consumption process of 2-methylfuran and 2,5-dimethylfuran are more similar. This is due to the similarity in their structures, both has methyl group connected directly to the furan ring. No furan has been observed in both the flames of 2-methylfuran and 2,5-dimethylfuran. It indicates that the consumption process of furan contribute little to 2-methylfuran and 2,5-dimethylfuran combustion.