Improved sooting tendency measurements for aromatic hydrocarbons and their implications for naphthalene formation pathways
Improved sooting tendency measurements for aromatic hydrocarbons and their implications for naphthalene formation pathways
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DOI：
10.1016/j.combustflame.2006.11.003
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发表时间：
2007-03
影响因子：
4.4
通讯作者：
C. McEnally;L. Pfefferle
中科院分区：
文献类型：
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作者：
C. McEnally;L. Pfefferle
碳烟生成趋势已被确定为芳烃使用一个新的定义：最大碳烟体积分数FV，最大测量在同向流动的甲烷/空气非预混火焰的燃料是掺杂400 ppm的测试烃。通过方程YSI=C×fv，max+D将这些fv，max转换为与设备无关的产率炭黑指数（YSI），其中C和D是设备特定参数，选择YSI-苯= 30，YSI-1，2-二氢萘= 100。用注射泵将掺杂剂添加到燃料混合物中，用激光诱导白炽测量fv，max。测定了6种环芳烃和62种芳烃的YSI，其中烷基苯28种，烯基苯10种，炔基苯10种，多取代苯25种，双环芳烃6种，侧链含杂原子的取代苯6种。YSI与阈值炭黑指数（TSI）的文献值相关性很好，TSI是一种更传统的基于纯燃料火焰在烟点处的高度的炭黑趋势。这一协议表明，fv，最大值和烟高度是等效的措施，炭黑的倾向，YSI是在很大程度上独立于设备。然而，YSI的总不确定度为± 3%，这比TSI好得多，并且这里报告的芳族YSI的数量是文献中芳族TSI数量的两倍多。的YSI强烈依赖于分子结构，因此，他们提供了有关的化学动力学反应机制负责燃料分解和碳氢化合物的增长从一个广泛的横截面的单环芳烃。重要的萘形成途径似乎包括乙炔加成到乙炔基苯基，炔丙基加成到苄基，和甲基加成到茚基。最后一种途径特别重要，因为它将茚定量转化为萘，并且因为许多烯基苯和炔基苯中的侧链环化形成五元环。
Sooting tendencies have been determined for aromatic hydrocarbons using a new definition: the maximum soot volume fraction fv,maxmeasured in a coflow methane/air nonpremixed flame whose fuel is doped with 400 ppm of the test hydrocarbon. These fv,maxwere converted into apparatus-independent yield sooting indices (YSIs) by the equation YSI=C×fv,max+D, where C and D are apparatus-specific parameters chosen so that YSI-benzene = 30 and YSI-1,2-dihydronaphthalene = 100. The dopants were added to the fuel mixture with a syringe pump and fv,maxwas measured with laser-induced incandescence. YSI was determined for 6 cycloaliphatics and for 62 aromatics, which included 28 alkylbenzenes, 10 alkenylbenzenes, 10 alkynylbenzenes, 25 multiply substituted benzenes, 6 two-ring aromatics, and 6 substituted benzenes with heteroatoms in the side chains. The YSIs correlate well with literature values of threshold sooting index (TSI), which is a more traditional sooting tendency based on the height of pure-fuelled flames at the smoke point. This agreement indicates that fv,maxand smoke height are equivalent measures of sooting tendency and that YSI is largely apparatus-independent. However, the YSIs have a total uncertainty of ±3%, which is substantially better than the TSIs, and the number of aromatic YSIs reported here is more than double the number of aromatic TSIs in the literature. The YSIs depend strongly on molecular structure; thus they provide information about the chemical kinetic reaction mechanisms responsible for fuel decomposition and hydrocarbon growth from a broad cross section of one-ring aromatics. Important naphthalene formation pathways appear to include acetylene addition to ethynylphenyl, propargyl addition to benzyl, and methyl addition to indenyl. This last pathway is particularly significant because it converts indene quantitatively to naphthalene and because the side chains in many alkenylbenzenes and alkynylbenzenes cyclize to form five-membered rings.