摘要
为了实时、在线研究一些固体物质的热裂解产物,自行搭建了一套热裂解-在线真空紫外光电离质谱装置。利用真空紫外灯作为电离源,并结合垂直引入飞行时间质谱,初步研究了聚丙烯在400~600℃和卷烟烟丝在400~700℃热解时释放的气相产物。本实验不仅在线获得了一系列热解气相产物的光电离质谱图,还了解了各产物,如丙烯（m/z42）、戊二烯（m/z68）等在不同温度下随时间的变化曲线,从而获知热解反应的动态变化过程。结果表明,真空紫外光电离质谱法是研究固体物热裂解的重要手段,可以为研究热解动态变化和产物形成机理提供重要信息。
An online pyrolysis-vacuum ultraviolet photoionization mass spectrometer（PY-VUV PIMS）was built for the analysis of pyrolysis products of solid materials.Vacuum ultraviolet photoionization is a ＂soft＂ionization method producing few or no fragments of molecular ions,making the identification and interpretation of complex pyrolysis products in real time possible.In this work,the gaseous pyrolysis of polypropylene at the temperatures range of 400℃to 600℃ were firstly studied with this new-built setup.A series of mass spectra of gaseous products were obtained,and the time-evolvedcurves for the products like propylene（m/z42）and pentadiene（m/z68）were also recorded.It was found that the increase of temperature can dramatically shorten the reaction time.Due to the effect of secondary reactions,the formation time of pentadiene is a little later than that of propylene produced only from primary reaction.Reactions like chain fission,back-biting,andβ-scission contribute to most of the primary reactions.The pyrolysis of tobacco was also performed with PY-VUV PIMS in the temperature range from 400 ℃ to 700 ℃,and the effects of reaction temperature on the pyrolysis products intensity were studied.For relative small molecular weight compounds like propylene（m/z42）,their relative intensities increase all the time as pyrolysis temperature rises.As for acetone/propanal（m/z58）and some other compounds,their relative intensities first rise to the maximum and then decrease.In the case of relatively large molecular weight compounds like nicotine（m/z 162）,they decrease with temperature increases,indicating that it have suffered secondary reactions under high temperature and decomposed into small molecules.Results show that vacuum ultraviolet photoionization mass spectrometry is a powerful method for pyrolysis study,which can offer important information for learning the pyrolysis mechanisms and dynamic processes.
出处
《质谱学报》
EI
CAS
CSCD
北大核心
2015年第6期513-520,共8页
Journal of Chinese Mass Spectrometry Society
基金
国家自然科学基金(11175185
U1432128)资助
关键词
固体物
光电离质谱
热裂解
气相产物
实时研究
solid materials
photoionization mass spectrometry
pyrolysis
gaseous products
online
