菜籽油生物柴油化学动力学机理的构建

Construction of Chemical Kinetics Mechanism for Rapeseed Oil Biodiesel

采用气-质联用仪测量了以菜籽油为原料制备的生物柴油的酯类组成成分和比例,根据主要组分的分子式和含量,拟合得到生物柴油的分子式。确定了以丁酸甲酯和正庚烷组成的混合燃料来替代生物柴油,采用"叠加法"构建得到一种新的生物柴油化学动力学机理。通过对影响主要污染物生成的基元反应进行敏感性分析,筛选出新机理中需要修正的基元反应。调整指前因子修正化学反应速率常数,模拟不同扰动下CO2和C2H4的摩尔分数,分析模拟结果与试验结果的平均误差。研究结果表明:生物柴油的拟合分子式为C19H36O2;丁酸甲酯和正庚烷组成的混合燃料在分子式、分子量、黏度等方面较丁酸甲酯与实际的生物柴油更为接近,可用来替代生物柴油;在指前因子略增大的扰动下,新机理计算的CO2和C2H4摩尔分数的平均误差均较小。

The ester components and their proportion of biodiesel fuel prepared by rapesee d oil were measured by gas chroma‐tography‐mass spectrometry and the molecular formula of biodiesel fuel was fitted according to the formula and content of main components .Then the prepared biodiesel was taken place by the equivalent blended fuel of methyl butyrate and n‐heptane and hence a new biodiesel chemical kinetic mechanism was constructed by superposition method .According to the sensitivity to ele‐mentary reaction of main pollutant formation ,the elementary reaction that needed to be corrected was screened .The chemical reaction rate constant was corrected by adjusting the pre‐exponential factor and then the mole fraction of CO2 and C2 H4 under different disturbance was also simulated .The average error between simulated and experimental results was analyzed .The re‐sults show that the fitting formula of biodiesel fuel is C19 H36 O2 .The molecular formula ,molecular weight and viscosity of blended fuel are closer to actual biodiesel compared with methyl butyrate and can be used as biodiesel .Due to the slight increase of pre‐exponential factor ,the average error for CO2 and C2 H4 mole fraction are both very small .