生物柴油的催化改性对其冷滤点的影响

利用HZSM-5型分子筛作为催化剂，在250℃～350℃、0.01MPa～0.04MPa的条件下，对生物柴油的主要组分油酸甲酯、棕榈酸甲酯、硬酯酸甲酯、亚油酸甲酯、月桂酸甲酯进行催化改性，以达到降低生物柴油冷滤点（CFPP）的目的。实验研究了反应温度和反应真空度对各脂肪酸甲酯产物的冷滤点、结炭率、碘值的影响，以该实验数据为依据，将动物油经过酯交换制备的生物柴油（AFE）进行催化改性。结果表明，在300℃~350℃，对饱和脂肪酸甲酯改性有很好的降凝效果，产物碘值升高；油酸甲酯通过改性，也取得了很好的降凝效果，产物碘值下降，在该反应条件下改性饱和脂肪酸甲酯和油酸甲酯催化剂的结炭率保持在5%以下；而亚油酸甲酯仅在350℃时改性才有降凝效果，且结炭率在10%以上。生物柴油（AFE）催化改性达到最佳降凝效果的条件为300℃~325℃，0.01MPa，改性后的的酸值小于0.6mg/g，冷滤点下降了19℃，碘值（I.V）为44.32g/100g，运动黏度（μ_t）为4.397mm²/s，并且催化剂结炭率保持在5%以下。

Effect of modification of biodiesel by HZSM-5 zeolite on cold filter plug point

The main components of biodiesel including methyl oleate, methyl palmitate, methyl stearate, methyl linoleate and methyl laurate were modified at 250℃~350℃ using HZSM-5 zeolite catalyst to decrease the cold filter plug points(CFPP) of biodiesel. The influences of temperature and vacuum on the cold filter plug points(CFPP), coke deposits and iodine value were studied. The results show that at 300℃~350℃ an significant decrease of cold filter plug points is made, and the amount of coke deposits is less than 5%; meanwhile, the iodine value of methyl oleate is reduced. However, the iodine values of modified saturated fatty acid esters are increased. For the modification of methyl linoleate, the cold filter plug points of modified product do not decrease unless it is reacted at 350℃, and the amount of coke deposits is more than 10%. As the biodiesel from the transesterification of animal fats with methanol（AFE）is modified, the cold filter plug point(CFPP) can be decreased by 19℃ at 325℃ and 0.01MPa. Meanwhile, the acid value of the biodiesel is less than 0.6mg/g, the iodine value(I.V) is 44.32g/100g, the kinematic viscosity(μ_t) is 4.397mm²/s, and the amount of coke deposits is less than 5% .