高温煤焦油的超临界萃取分馏研究

Supercritical fluid extraction and fractionation of high-temperature coal tar

采用正戊烷溶剂,在超临界状态下,于220℃和5MPa^15MPa循序升压条件下,将高温煤焦油萃取分馏为10个液相窄馏分和1个固相沥青产物;切割深度达78.36%,萃余沥青收率为21.64%,明显低于常规蒸馏沥青收率。研究发现,所用高温煤焦油的初馏分萃取收率最高,随着萃取压力的增加,较低压力段一次萃取液相馏分的收率迅速减少;压力达到10 MPa,液相馏分总收率趋于峰值。元素分析和色质联用分析数据表明,随着萃取压力的增加,一次萃取获得窄馏分的碳氢原子比逐渐增加,平均环数和相对分子质量均逐渐增大,萃取馏分逐渐变重。

The high-temperature coal tar sample was separated into 10 narrow oil fractions and one solid-phase pitch product by supercritical fluid extraction and fractionation using n-pentane as solvent at 220 ℃ and pressure from 5 MPa to 15 MPa.Results show that the accumulative yields increase with the extract pressure especially at the lower pressures,and the yield increase rate decrease gradually.The total yield of the oil extract is 78.36%,and the raffinate pitch yield is 21.64% which is far below that of the conventional distillation.Elemental analysis and chromatograph-mass spectrometer analysis show that with the increase of the extraction pressure,the atomic ratio of carbon to hydrogen,the average ring numbers,as well as the average molecular weight of narrow oil fractions increase gradually.