异戊醇低压热解的同步辐射真空紫外光电离质谱研究

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

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C4H8O、C5H8、C6H6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。

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 C 4H 8O,C 5H 8,C 6H 6,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.