Experimental study of nitropropane pyrolysis with molecular-beam mass spectrometry and tunable synchrotron VUV photoionization. Part I. The flow reactor pyrolysis of 1-nitropropane

An experimental study of 1-nitropropane (1-NP) pyrolysis was performed in a flow reactor at low pressure (4.0 kPa) in the temperature range of 623–973 K. The pyrolysis species was detected with the tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry (MBMS). Species from m/z = 15–87 were identified from near-threshold photoionization efficiency (PIE) spectra, such as radicals of CH 3 , C 2 H 5 , C 3 H 5 and C 3 H 7 ; isomers of C 2 H 4 O (ethenol and acetaldehyde), C 3 H 6 O (acetone and propanal), C 4 H 10 (butane and isobutane), HNC (hydrogen isocyanide), HCN (hydrogen cyanide)), C 3 H 5 N (ethyl isocyanide and species with unidentified structure) and C 3 H 5 NO (methoxyacetonitrile and species with unidentified structure). Their mole fraction profiles were evaluated at different temperature. Based on the mole fractions of species measured at the minimum temperature of 1-NP pyrolysis, some new channels of 1-NP primary pyrolysis were speculated, such as the channels involving O-transfer from N to C-atoms in different positions, deoxygenation, dehydrogenation and OH-abstraction. Based on the mechanisms proposed in the literature, the species produced from secondary or subsequent reactions were also discussed. These results are valuable to a further quantum mechanical calculation for a better understanding of 1-NP chemistry.