CI—MS法检测渣油中的石油酸

Determination of Petroleum Acids in Vacuum Residue by CI-MS

采用柱色谱和阴离子交换树脂法分离渣油馏分中的羧酸,通过红外光谱仪检验分离出的羧酸类型。将石油酸和异丁烷反应气引入到离子源进行化学电离(CI)—质谱(MS)法分析,这些离子可以用来计算石油酸的相对分子质量。以纯脂肪酸、环烷酸以及分离出的石油酸的 CI 质谱数据为基础,并结合环烷酸 z 系列通式 C_nH_(2n+z)O_2分别得到了不同碳数的脂肪酸、一环、二环……六环环烷酸的分析结果。结果表明,渣油中的羧酸主要是环烷酸,相对分子质量分布在198～540,碳数分布在 C_(12)～C_(37),其中三环、四环环烷酸含量较高。

The petroleum carboxylic acid in vacuum residue distillates of crude oil was separated by the extraction with column chromatogram and anion exchange resin. Composition and structure of naphthenic acids were obtained by the use of IR techniques. Petroleum acids with iso--butane reagent gas was introduced to ion source that can be ionized by chemical ionization （CI）--mass spectrometer（MS）. These ions can be used to calculate the molecular mass for each acid as previously described. Based on mass spectrum of pure fatty and naphthenlc acid and combined with z- series formula Cn H2n＋xO2. The type of naphthenic acids can be classified into fatty, mono- , bi-… hexa-cyclic according to their mass spectrum and data. The results indicate that naphthenic acid is the main composition of vacuum residue and the molecular weight distribution of petroleum acids in this distillate is about 198~540,and the carbon number distribution is about C12 -C37. The contents of tri- cyclic and tetra-cyclic naphthenic acids are higher than others.