摘要:
以大豆油为原料采用碱催化酯交换法合成生物柴油，测定了其酸值、游离甘油、总甘油、灰分、黏度和磷含量等指标。实验表明,共存的甲醇、水分和甘油酯对生物柴油的低温流动性能影响极少，饱和脂肪酸甲酯的同时析出对生物柴油低温流动性能起关键作用。考察了5种柴油降凝剂、0号和20号柴油以及乙醇对生物柴油低温流动性能的影响。0号柴油有效地改善生物柴油黏度，但对其低温流动性能影响不大。20号柴油和乙醇能显著降低生物柴油的凝点、倾点、冷滤点和黏度。其中3种降凝剂有效降低生物柴油的凝点和倾点，1种降凝剂能小幅度改善冷滤点，5种降凝剂都能使生物柴油的黏度小幅上升。
Abstract:
A bio-diesel fuel sample, methyl esters from soybean oil (SME), was prepared by basic catalysis and transesterification. The important characteristics such as acid value, free glycerol, viscosity (ν), total glycerol, ash and phosphor content were determined. The v and the low-temperature flowing properties (LTFP) such as solidification point (SP), pour point (PP) and cold filter plugging point (CFPP) were tested by standard petroleum methodologies. LTFP of SME is hardly influenced by methanol, water and glyceride that exist in SME when their contents are less than their specifications required. When SME is cooled, the saturated fatty acid methyl esters (FAME) in SME will co-crystallize first. Thus LTFP of SME is greatly influenced by the saturated FAME in SME. Then the approaches for improving LTFP of SME were explored. Five cold-flow additives, No.0 diesel fuel (DF0), No-20 diesel fuel (DF-20) and ethanol were tested. DF0 can improve ν of SME, but can not greatly affect LTFP of SME. DF-20 and ethanol can greatly improve CP, PP, CFPP and ν of SME. Three cold-flow additives can greatly reduce SP and PP of SME, but only one can improve CFPP a little. All five cold-flow additives can increase ν of SME.
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