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

Abstract

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 CH3, C2H5, C3H5 and C3H7; isomers of C2H4O (ethenol and acetaldehyde), C3H6O (acetone and propanal), C4H10 (butane and isobutane), HNC (hydrogen isocyanide), HCN (hydrogen cyanide)), C3H5N (ethyl isocyanide and species with unidentified structure) and C3H5NO (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.