The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 speci...The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 species, especially several radicals and isomers, were detected and identified from the measurements of photoionization efficiency （PIE） spectra. Based on the mass spectrometric analysis, the characteristics of n-butane and i-butane pyrolysis were discussed, which provided experimental evidences for the discussion of decomposition pathways of butane isomers. It is concluded that the isomeric structures of n-butane and i-butane have strong influence on their main decomposition pathways, and lead to dramatic differences in their mass spectra and PIE spectra such as the different dominant products and isomeric structures of butene products. Furthermore, compared with n-butane,i-butane can produce strong signals of benzene at low temperature in its pyrolysis due to the enhanced formation of benzene precursors like propargyl and C4 species, which provides experimental clues to explain the higher sooting tendencies of iso-alkanes than n-alkanes.展开更多
基金This work is supported by the National. Natural Science Foundation of China （No.51106146, No.51036007, No.U1232127）, the China Postdoctoral Science Foundation （No.20100480047 and No.201104326）, the Chinese Universities Scientific Fund （No.WK2310000010）, the Anhui Science ＆ Technology Department （No.l1040606Q49）, and the Chinese Academy of Sciences.
文摘The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 species, especially several radicals and isomers, were detected and identified from the measurements of photoionization efficiency （PIE） spectra. Based on the mass spectrometric analysis, the characteristics of n-butane and i-butane pyrolysis were discussed, which provided experimental evidences for the discussion of decomposition pathways of butane isomers. It is concluded that the isomeric structures of n-butane and i-butane have strong influence on their main decomposition pathways, and lead to dramatic differences in their mass spectra and PIE spectra such as the different dominant products and isomeric structures of butene products. Furthermore, compared with n-butane,i-butane can produce strong signals of benzene at low temperature in its pyrolysis due to the enhanced formation of benzene precursors like propargyl and C4 species, which provides experimental clues to explain the higher sooting tendencies of iso-alkanes than n-alkanes.
