Isomer-specific influences on the composition of reaction intermediates in dimethyl ether/propene and ethanol/propene flame.
Isomer-specific influences on the composition of reaction intermediates in dimethyl ether/propene and ethanol/propene flame.
复制标题
DOI：
10.1021/jp8011188
复制
发表时间：
2008-05
期刊：
影响因子：
--
通讯作者：
Juan Wang;U. Struckmeier;Bin Yang;T. Cool;P. Oßwald;K. Kohse-Höinghaus;T. Kasper;N. Hansen
中科院分区：
文献类型：
--
作者：
Juan Wang;U. Struckmeier;Bin Yang;T. Cool;P. Oßwald;K. Kohse-Höinghaus;T. Kasper;N. Hansen
这项工作提供了实验证据，如何富燃料的低压预混火焰的分子组成的含氧化合物二甲醚（DME）或乙醇的增量共混到丙烯燃料的影响。10个不同的火焰与碳氧比为0.5，范围从100%丙烯（φ = 1.5）到100%含氧燃料（φ = 2.0），分析火焰采样分子束质谱采用电子或光电离。火焰物种的绝对摩尔分数分布与质量范围从m/z = 2（H2）到m/z = 80（C6 H8）进行了分析，特别强调有害排放物的形成。燃料特定的销毁途径，可能是由氢提取启动，似乎导致苯从丙烯燃烧和甲醛和乙醛通过二甲醚和乙醇燃烧，分别。当丙烯被乙醇取代时，乙醛的浓度增加10倍，而当丙烯被DME取代时，乙醛的浓度降低。相比之下，甲醛浓度仅略有上升，乙醇替代，但增加显着与添加DME。烯丙基和炔丙基自由基是苯形成的主要前体，可能直接由丙烯分解或通过丙二烯和丙炔产生。苯的形成通过炔丙基自由基形成的二甲醚和乙醇的分解中的不饱和C2中间体是微不足道的。因此，DME和乙醇的加入导致类似的苯浓度的降低。
This work provides experimental evidence on how the molecular compositions of fuel-rich low-pressure premixed flames are influenced as the oxygenates dimethyl ether (DME) or ethanol are incrementally blended into the propene fuel. Ten different flames with a carbon-to-oxygen ratio of 0.5, ranging from 100% propene (phi = 1.5) to 100% oxygenated fuel (phi = 2.0), are analyzed with flame-sampling molecular-beam mass spectrometry employing electron- or photoionization. Absolute mole fraction profiles for flame species with masses ranging from m/z = 2 (H2) to m/z = 80 (C6H8) are analyzed with particular emphasis on the formation of harmful emissions. Fuel-specific destruction pathways, likely to be initiated by hydrogen abstraction, appear to lead to benzene from propene combustion and to formaldehyde and acetaldehyde through DME and ethanol combustion, respectively. While the concentration of acetaldehyde increases 10-fold as propene is substituted by ethanol, it decreases as propene is replaced with DME. In contrast, the formaldehyde concentration rises only slightly with ethanol replacement but increases markedly with addition of DME. Allyl and propargyl radicals, the dominant precursors for benzene formation, are likely to be produced directly from propene decomposition or via allene and propyne. Benzene formation through propargyl radicals formed via unsaturated C2 intermediates in the decomposition of DME and ethanol is negligibly small. As a consequence, DME and ethanol addition lead to similar reductions of the benzene concentration.