生物柴油对低硫柴油润滑性的增进作用

用菜籽油、大豆油以及芸香籽油制备了多种脂肪酸低碳醇酯即生物柴油，用高频往复试验机法（HFRR）考察了生物柴油对低硫柴油润滑性的增进作用。研究结果表明，生物柴油对低硫柴油润滑性有增进作用，但添加质量分数在0．2％以下时效果不明显；柴油组分不同，对生物柴油的感受性也不同：对于馏分较重、粘度较大的柴油，生物柴油的添加量只需超过2．0％其润滑性就能满足标准要求（磨斑直径不大于460／μm）；而对于馏分较轻、粘度较小的柴油，需添加4．0％～5．0％才能使其润滑性满足要求；生物柴油的烷氧基链长对其润滑性没有明显影响，而甘油单酸酯或游离脂肪酸等杂质能够显著提高其润滑性；以不同植物油为原料制备的生物柴油在较低的添加比例下对低硫柴油的润滑性没有明显的不同，超过2．0％以后略有差别。

EFFECT OF BIO-DIESEL ON LUBRICITY OF LOW-SULFUR DIESEL FUELS

A series of fatty acid esters with low aliphatic alcohols (bio-diesel) samples was prepared by vegetable oils, such as colza oil, soybean oil and etc., and the effect of adding bio-diesel samples to the low-sulfur or ultra low-sulfur diesel fuels on the lubricity was investigated by using high frequency reciprocating rig (HFRR). The results of HFRR test showed that when the adding dosage of fatty acid methyl esters was below 0.2%, no positive effect was observed; the optimum adding dosages of fatty acid methyl esters for the heavy-viscose diesel and light diesel to meet the limit of EN 590 were 2.0% and 4.0%~5.0%, respectively. No significant relationship was found between the chain length of alcohols on the esters and the lubricity. However, it was observed that certain impurities, such as monoglycerides and free fatty acids, in fatty acid esters even at a trace level, could significantly reduce the size of wear scar. Esters produced by different vegetable oils showed same effect or slightly different effects at adding dosage below or above 2.0%, respectively.