无需辅助识别的石油产品酸值测定方法

为改变GB/T 7304标准法试样溶剂配方,提高甲苯比例,并以乙醇替代异丙醇、碱性试剂二甲亚砜替代水,提高了难溶油品的溶解性能,增强了油品酸性物质的表观酸度,滴定终点无需非水缓冲溶液辅助识别,克服了标准法溶解性能力的不足和所使用的非水缓冲溶液毒性大的难题。本法溶剂组成为甲苯/乙醇/二甲亚砜(3/1/1.2%),所用试剂可100%溯源,与标准法结果具有一致性,相对误差均小于6.0%的允许偏差,为准确测定多种油品的酸值提供了一个较好的方案。

IMPROVED METHOD FOR ACID NUMBER ANALYSIS OF PETROLEUM PRODUCTS WITHOUT AUXILIARY ESTIMATION USING STANDARD BUFFER SOLUTION

In order to improve the composition of the mixture solvents for the determination of acid number according to GB/T 7304,isopropyl alcohol was replaced by ethanol,the proportion of toluene was increased,and water was replaced by dimethylsufoxide(DMSO).In this way,both the apparent acidity of the acidic component of the sample and the solubility of the mixture solvent to Heavy Oils were enhanced.The drawbacks of the original method such as the use of auxiliary solvent,low solubility and toxicity of non aqueous solution were eliminated.The new solvent consisted of 1.2% DMSO,as a weak base,in a mixture of toluene and ethanol,3:1(volume fraction).The improved method iS free from auxiliary non-aqueous buffer solution for the estimation of the end point in titration and accurate,with relative deviation less than acceptable 6.0%,offering a good alternative for the determination of acid numbers of petroleum products.