环烷酸的结构分析及对燃料润滑性的影响

采用IR、NMR和ESI( )/MS对环烷酸添加剂的结构进行表征,并在实验室对环烷酸进行分割得到改进型环烷酸,采用高频往复试验机考察了环烷酸和改进型环烷酸对超低硫柴油燃料润滑性能的影响,探讨了环烷酸的抗磨机理。结果表明,环烷酸主要以五元和六元环结构的环烷酸组成,芳环含量极少,纯度较高;环烷酸中的烷基链异构程度较高,羧基碳的含量约为685%(质量分数);环烷酸以一、二环环烷酸为主,脂肪酸、三环环烷酸、四环环烷酸、芳环羧酸的含量都很低。在满足柴油润滑性要求的前提下,改进型环烷酸比未改进环烷酸的添加量减少了25%(质量分数),对超低硫柴油燃料润滑性能的提高明显优于未改进环烷酸。空白油样的试球磨斑表面未发现氧元素,而含改进型环烷酸油样的试球磨斑表面氧元素的质量分数比含未改进环烷酸油样的高296%。

Structure of Naphthenic Acids and Its Effect on the Lubricity of Super-Low Sulfur Fuel

The structure and composition of naphthenic acids(NA) were characterized by Infrared spectrometer, NMR and ESIMS. The improved naphthenic acids(I NA) was obtained through distillation method. The tri bological properties of NA and I NA as lubricating additives were evaluated by the high frequency reciprocating rig (HFRR) and the mechanism was also explored. The results showed that the NA was mainly composed of five and six ring naphthenic acids with extremely content of aromatic ring. The alkyl chain of NA was higher degree of isomerization, and mass fraction of the carboxyl carbon to total carbon was about 685%. The NA were mainly one and two ring NA with few fatty acids, aromatic ring naphthenic acids, three and four ring ones. Comparing to NA, the addition of I NA was reduced by 25% (mass fraction) to meet the lubricity requirements of the ultra low sulfur diesel fuel. A better lubricating behavior of I NA on the base fuel was indicated. There was no oxygen on the worn surface lubricated by the fuel sample, while the mass fraction of oxygen on the worn surface lubricated by the fuel sample with I NA addition was even 296% higher than that lubricated by the fuel sample with NA addition.