Abstract:   The biodiesel from Jatropha oil was modified by Hβzeolite catalyst in a fixed bed reactor，and the improvement of low temperature fluidity was found. The best reaction condition is as follow：catalyst SAR is 25，reaction temperature is 250 ℃，WHSV is 1.0 h^－1，addition（H₂O）loading is 1.2%. The solidifying point of biodiesel was decreased by up to 6 ℃. The modified products were analyzed by NMR，GC-MS characterization. The reason for improved low temperature flow properties is the isomerization of the main components of biodiesel：methyl oleate，methyl linoleate，etc.

Key words:  , biodiesel；low temperature fluidity；isomerization；solidifying point

摘要： 以小桐梓油生物柴油为原料，在固定床连续反应器中，以Hb型分子筛为催化剂，采用异构化反应改善生物柴油的低温流动性。考察了反应温度、质量空速、助剂（水）加入量等不同条件对生物柴油低温流动性的影响。实验结果表明，催化剂选用硅铝比为25的Hb分子筛的情况下，反应温度为250 ℃、质量空速为1.0 h^－1、助剂加入量为1.2%为最佳反应条件，小桐梓油生物柴油在最佳反应条件下进行异构化反应，凝点从1 ℃降低到－5 ℃，降幅为6 ℃。对生物柴油和异构化产物进行了色谱、质谱、核磁共振等表征，结果发现，低温流动性改善的原因是生物柴油的主要成分油酸甲酯、亚油酸甲酯发生了异构化反应，产生了带支链的异构体。

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