吸热型碳氢燃料裂解引发剂筛选及引发机理分析

Screening Experiments for Initiators and Initiating Mechanism for the Cracking of the Endothermic Hydrocarbon Fuel

筛选可溶性添加剂替代多相催化剂,达到促进吸热型碳氢燃料裂解、提高燃料热沉以及燃烧性能的目的.采用考察裂解气相产物气体流量的方法进行实验.测试了10种添加剂在500～650℃范围内对正庚烷裂解效果的影响.研究发现,三乙胺、2,6-二叔丁基对甲酚(BHT)可促进正庚烷裂解,其它添加剂均无显著效果.在550℃时,当三乙胺质量分数达到6%时,实验总气体收率比计算总气体收率增加80%以上.机理研究表明,三乙胺的引发剂基团来源于C—N键的断裂.BHT的结构、性状与前者显著不同,在550℃时,当BHT质量分数为3.4%时体系的气体收率较之纯正庚烷裂解气体收率增加80%以上,BHT的引发基团主要是连接于叔丁基上的甲基发生脱离的结果.

Initiators to promote the cracking of the endothermic hydrocarbon fuel were screened. The flow rate of gas products was measured by a water-displacement method. Triethylamine and butylated hydroxytoluene （BHT） were found to be effective on promoting the cracking of heptane at 500-650℃. For the triethylamine system, the experimental yield of total gas product could be 80% higher than that calculated by neglecting the interaction between triethylamine and heptane as the mass fraction of triethylamine reached 6% at 550 ℃. The accelerating mechanism was studied by gas chromatography-mass spectrometry （GC-MS）. It was demonstrated that the accelerating effect originated mainly from the initiative release of CH3CH2· from triethylamine by the scission of the C-N bond. For BHT, the initiating radicals were mainly produced by the scission of the bond between the tert-butyl carbon atom and methyl radical.