异戊醇低压热解的同步辐射真空紫外光电离质谱研究

作为新兴生物燃料,大分子醇类燃料在低压下的火灾安全基础迫切需要得到深入研究。热解过程作为火灾过程的初始阶段直接控制着火过程,火灾中碳烟颗粒的产生也依赖于热解反应,因此可燃物的低压热解研究在其低压火灾基础研究中具有重要意义。利用同步辐射真空紫外光电离质谱方法研究了异戊醇在0.2atm下的流动反应器热解,探测到了20余种热解产物,包括烯丙基自由基和C_4H_8O、C_5H_8、C_6H_6等同分异构体,并测量了其摩尔分数。基于实验结果,对燃料分解路径和主要产物的生成及消耗路径进行了探讨。与本组之前正戊醇热解实验的对比表明,由于存在支链结构,异戊醇在热解中比正戊醇更容易产生戊烯、丁烯和丙烯,但更少地产生乙烯。此外,异戊醇在热解中能够生成更多的丙炔和丙二烯等环状化合物前驱体,令其苯和1,3-环戊二烯的生成量更高,表明异戊醇比正戊醇更易于生成多环芳烃和碳烟。

Investigation on low-pressure pyrolysis of iso-Pentanol with synchrotron VUV photoionization mass spectrometry

There is a growing demand in the fundamental fire safety research under low pressures for long carbon-chain alcohols which are a kind of novel biofuels. As the initial stage of fire, pyrolysis process directly controls the ignition process, while the formation of soot particles in fire also depends on pyrolysis reaction. Therefore, the research on low-pressure pyrolysis of combustibles is of great significance in the fundamental research of low-pressure fire. In this work, the pyrolysis of iso-pentanol was studied in a flow reactor at 0.2 atm using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). More than 20 pyrolysis products were detected, especially allyl radical and isomers of C4H8O, C5H8, C6H6, etc. Their mole fractions were also measured. Based on the experimental observations, the fuel decomposition pathways and the formation and consumption pathways of major pyrolysis products were discussed. The comparison with our previously reported n-pentanol pyrolysis experiment shows that iso-pentanol pyrolysis produces more pentene, butene and propene, but obviously less ethylene. In addition, iso-pentanol can produce more precursors of cyclic compounds such as propyne and allene during pyrolysis, resulting in higher yields of benzene and 1,3-cyclopentadiene, implying iso-pentanol was easier to generate more polycyclic aromatic hydrocarbons and soot.