中温煤焦油沥青的超临界溶剂抽提和分离

用超临界溶剂在半连续装置上对中温煤焦油沥青（ＭＣＴＰ）进行了抽提和分离，考察了抽提段的实验条件对灰分和吡啶不溶物（ＰＩ组分）脱除率的影响；在分离段使用升温和／或降压法、精馏法调节ＭＣＴＰ族组成分布，并用分步抽提法调节ＭＣＴＰ的族组成。实验表明：用甲苯为超临界溶剂抽提可脱除全部灰分，ＰＩ组分也可在较低的压力下选择性地脱除；采用升温和／或降压法对抽出物可进行一定程度的分离，但对庚烷可溶物（ＨＳ组分）分离的选择性不高；采用精馏法可选择性地脱除ＨＳ组分，但尚需改进设备进一步提高分离效率；采用分步抽提法用石油醚作一次抽提溶剂可高选择性地脱除ＨＳ组分，其选择性在９５％以上。

SUPERCRITICAL FLUID EXTRACTION ADN SEPARATION OF MEDIUM COAL TAR PITCH

Sequential extraction and separation of medium coal tar pitch(MCTP)usingsupercritical fluid were carried out in semicontinuous apparatus. Effect of the experimentalconditions on decreasing ash and pyridine insoluble(PI)fraction in extracted pitch was in-vestigated.Generic composition of MCTP was adjusted in separator by using different sepa-rating methods(decreasing pressure and/or increasing temperature,distillation).Step- wise extraction was also employed to modify generic composition of MCTP. It was concludedthat ash in the extracted pitch was completely eliminated under experimental conditions andPI fraction was selectively removed under low pressure by using supercritical toluene as ex-tractive solvent. On-line separation of extracted pitch by decreasing pressure and/or in-creasing temperature in separator showed significant difference of generic composition be-tween two fractions, but the difference of heptane soluble(HS)fraction was relativelysmall.On-line distillation selectively enriched HS fraction of extracted pitch,but recon-struction of the separating column was required to achieve the better results.Step-wise ex-traction using various solvents successfully regulated generic composition of MCTP.At firststage HS fraction of MCTP was almost completely extracted by supercritical petroleum etherwith high selectivity,then supercritical toluene was conducted to extract residual pitch,Thus,a pitch with narrow generic composition distribution was obtained.