Abstract:

Combination of pour point depressants（PPDs）is one of the effective means to improve low temperature properties of diesel fuel. In this paper 0^# diesel fuel was used to evaluate the effect of different PPDs，then PPDs with good effects were combined. Digital X-ray diffraction（XRD），micropolariscope and differential scanning calorimeter（DSC）were used to study the influence of PPD on the growth of wax crystal and thermodynamics of crystallization at a low temperature. The results showed that combination of polymethacrylate PPD（KT4）and polyethylene-viny acetate PPD had better effect especially at the ratio of 1︰1. XRD and micropolariscope indicated that adsorption was the mechanism of polymethacrylate PPD（KT4），while co-crystallization was the mechanism of polyethylene-viny acetate PPD（AH-BSFH）. DSC showed that 1︰1 combination of polymethacrylate PPD（KT4）and polyethylene-viny acetate PPD could further lower the liquid-solid phase change.

摘要：

柴油降凝剂复配是有效提高其在柴油中降凝效果的手段之一。本文主要考察了不同类型柴油降凝剂在0^#柴油中的降凝效果，筛选出其中效果较好的降凝剂进行复配，并考察了不同配比对其降凝效果的影响，最终采用低温原位X射线衍射、低温偏光显微镜和差示扫描量热法对比研究了柴油降凝剂加入前后对柴油蜡晶的生长规律和低温结晶热力学的影响。结果表明，聚甲基丙烯酸酯类降凝剂KT4与聚乙烯-乙酸乙烯酯类降凝剂AH-BSFH复配起到协同作用，具有更好的降凝效果，其最佳复配比例为1∶1。XRD、低温偏光显微镜的分析结果表明，KT4降凝剂主要是通过吸附理论来降凝，AH-BSFH降凝剂主要是通过共晶理论来降凝。DSC分析结果证明，KT4与AH-BSFH按1∶1复配后使蜡晶的固-液相变能下降得更多，提高了降凝剂与蜡的匹配性，从而起到了协同作用。