超声包合法分离测定重质油中链烷烃和环烷烃

重质油中链烷烃与环烷烃的分离分析是烃类分析的难点,本文将超声波技术与尿素、硫脲包合法相结合,对大庆减压馏分油进行了链烷烃和环烷烃的分离试验,并用GC/MS和NMR对分离后的组分进行了研究.当活化剂异丙醇与油样品的质量比为7.5、包合反应温度为38~43℃时,5次重复试验测得链烷烃和环烷烃的平均质量分数分别为46.56%和41.88%,相对标准偏差分别为0.7%和0.51%.链烷烃中正构烷烃的碳数分布为C20—C38,其中环烷烃的含量低于NMR的检测限,环烷烃的总离子流色谱图显示出其中的链烷烃含量很低.研究结果表明超声波对尿素、硫脲包合反应有明显的促进作用,能显著地提高重质油中链烷烃和环烷烃的分离效果,该方法测定重质油中链烷烃和环烷烃的含量准确度高、重复性好.

Separation and determination of alkane and cycloparaffinic hydrocarbon in heavy oil by combining ultrasonic wave with the adductions of urea and thiourea

The separation and determination of alkane and cycloparaffinic hydrocarbon in heavy oil is the difficult problem in hydrocarbons analysis.The alkane and the cycloparaffinic hydrocarbon in Daqing VGO are separated by combining ultrasonic wave with the adductions of urea and thiourea.The obtained alkane and cycloparaffinic hydrocarbon are determined by GC/MS and NMR.When the mass ratio of isopropanol to oil sample is 7.5 and the temperature of reaction is 38～43 ℃,the average mass fractions of alkane and cycloparaffin in Daqing VGO are 46.56% and 41.88% and the RSD are 0.7% and 0.51% respectively according to 5 determination results.The carbon number distribution of normal paraffin in alkane is C_ 20 —C_ 38 .Cycloparaffinic hydrocarbon in alkane is less than the detection limit of NMR,and the total ion chromatogram of cycloparaffinic hydrocarbon shows that the content of alkane in cycloparaffinic hydrocarbon is very little.These indicate that ultrasonic wave can accelerate the adduction of urea and thiourea and improve the separation result of alkane and cycloparaffinic hydrocarbon in heavy oil.This method has high accuracy and good repeatability in the separation and analysis of alkane and cycloparaffin in heavy oil.