生物柴油多组分替代混合物化学反应路径分析

采用MD、MD9D和正庚烷三组分作为生物柴油混合替代物,替代物机理包含3 299种组分、10 806个基元反应。应用CHEMKIN-PRO反应速率分析法对燃烧氧化过程中燃料分子高低温主要反应路径和重要中间组分衍化过程进行了详细探究。结果表明:MD和MD9D在低温阶段主要通过脱氢加氧、异构化反应以及酮类物质的分解反应进行消耗,高温阶段主要是低温反应中间产物C—O、C—C键β分解反应、部分高温脱氢以及异构化反应最终生成C_2H_4等小分子产物。另外,MD和MD9D中不同碳原子位置C—H键能不同,邻近羧基以及C≡C双键碳原子处C—H键较弱,易发生脱氢反应生成烷酯基。在过氧酯基异构化生成过氧羧酯基过程中,不同环数过渡环张力大小以及反应势垒不同,异构化难易程度不同,而六元过渡环的张力较小,反应势垒较低,最易发生异构化反应,异构化反应产物更多。

Analysis of Biodiesel Fuels Blend Surrogate Chemical Reaction Path

A detailed chemical kinetic mechanisms of methyl decenoate, methyl-9-decenoate and n-heptane including 3299 species and 10806 reactions was selected as biodiesel fuels blend surrogate. The low-temperature and high-temperature reaction pathways and important intermediate component derivation process were analyzed by CHEMKIN-PRO rate of production analysis in this study. The results showed that H-atom abstraction and oxygen addition reaction,molecular isomerization and ketone decomposition reactions is the main path of methyl decenoate, methyl-9-decenoate consumption in the low temperature stage, the intermediate products from low temperature reaction form small molecules such as C2H4 etc though C-O, C-C bonds beta-decomposition, partial high temperature dehydrogenation and isomerization reactions mainly in high temperature stage. In addition, the carbon atom at different sites show obvious different C-H bond energies, H-atom abstraction was easily occured to form alkyl ester adjacent to carboxyl and C=C double bond cause that the C-H bond energies is weak in those locations.Different number of the ring have different reaction barrier, tension of transition ring and degree of isomerization in the process of peroxide ester group isomerize to carboxy peroxide ester group,the six-member transition ring were most likely to occur isomerization reaction to form more isomerization products caused that the tension of six-member transition ring is lesser and the reaction barrier is low.