The Effect of Molecular Structure and Component Element on SOF Formation

柴油机排气微粒受燃料特性的影响。特别是酒精燃料在燃烧时形成的颗粒较少，但原因尚不清楚。为了减少柴油发动机排放中的颗粒物，了解颗粒物的形成过程非常重要。本文采用热裂解装置或流体反应管，研究了不同碳数的醇类和烃类燃料在氮气和氮氧混合气氛下的热裂解和缩聚过程。用气相色谱法分析了裂解、缩聚组分和氧化组分。根据碳数的不同，烃类燃料首先发生低沸点烃类，然后发生脱氢反应，通过缩聚反应生成苯化化合物。含有氧原子的酒精燃料部分氧化成醛，其中一些产生一氧化碳、二氧化碳和一些低沸点的碳氢化合物。与碳氢化合物燃料相比，较少的缩聚化合物如苯环化合物形成。即使有微量的氧气存在，颗粒体积也会急剧减小，因为一些具有丰富可燃性的裂解产物如乙炔和乙烯被氧化，从而抑制了缩聚反应。进入燃烧室的燃料由于压缩温度而受热，并裂解成沸点较低的碳氢化合物。苯环组分的形成是脱氢和缩聚的结果。随着烷基自由基的附着，这一过程继续进行，形成烷基苯和多环化合物，直到最终的SOF。

Exhaust particulate in diesel engines are affected by fuel properties. Especially alcohole fuels form less particulate on combustion, but the reason for this is not clear. To reduce particulate in the emissions of diesel engines it is important to understand the particulate formation process.This report investigates the thermal cracking and condensation polymerization process of alcohole and hydrocarbon fuels with different carbon number in nitrogen and nitrogen-oxygen mixed atmospheres using a thermal cracking appartus or fluid reaction tube. The cracking and condensation polymerization components as well as the oxidization components were analyzed with gas-chromatography.The results obtained in this investigation may be summarized as follows : Depending on the carbon number, hydrocarbon fuels into lower boiling point hydrocarbons followed by dehydrogenation and the formation of benzenering compounds through condensation polymerization. Alcohole fuels which contain oxygen atoms partially oxidize into aldehydes and some of these produces carbon monoxide and carbon dioxde and some lower boiling point hydrocarbons. Less condensation polymerization compounds such as benzene ring compounds form than with hydrocarbon fuels. in the presence of even traces of oxygen, the particulate volume decreases dramatically, because the condensation polymerization reaction is inhibited by some of the cracked products such as acetylene and ethylene which wied rich limit of inflammability is oxidized. The fuel introduced into the combustion chamber heats due to the compression temperature, and cracks into lower boiling point hydrocarbons. Benzene ring components are formed as a result of dehydrogenation and condensation polymerization. With the attachment of alkyl radicals the process progresses to form alkyl benzene and multiple ring compounds till the final SOF.