Abstract:

The tar pitch needed to be pretreated to remove the solid particles (called quinoline insoluble, QI) to obtain refined pitch as a precursor for the preparation of various functional carbon materials. Effect of pressure on the removal of QI in coal tar pitch and mixed pitch with biomass pitch by the solvent method was investigated. The QI content and yield of refined pitch under different pressures were tested. Nanometer particle size analyzer, SEM and high temperature viscometer were used to determine the morphology and particle size of QI particles and the viscosity of the system during the process of refining pitch. The results indicate that pressure has a slight effect on the QI content of refined pitch and a significant impact on the increase in refined pitch yield. The yield of refined coal tar pitch increases from 64.6%(mass fraction) at 0.1MPa to 84.3%(mass fraction) at 1MPa, and the QI content of refined pitch is maintained between 0.06%—0.1%(mass fraction). With the addition of 15% biomass tar pitch, the yield increases from 55.7%(mass fraction) at 0.1MPa to 72.5%(mass fraction) at 1MPa. Increasing of pressure is beneficial for the solubility of the solvent, especially for the dissolution of heavy components. Higher pressure also increases the viscosity of the medium, which makes it difficult for some QI particles to settle, but the effect is small. The refined pitches are used to prepare mesophase pitches with flow domain-like texture. Adding biomass pitch can better improve the flow domain-like microstructure.

Key words: solvent extraction, sedimentation, separation, pyrolysis

摘要：

精制沥青是制备各种功能炭材料的前体，焦油沥青需要预处理脱除其中的固体颗粒物（称为喹啉不溶物，QI）以得到精制沥青，压力是脱除QI的重要条件。本文以煤焦油沥青和添加生物质沥青的混合沥青为原料，研究压力对溶剂法脱除固体颗粒物的影响，测试不同压力下精制沥青的QI含量及产率，利用纳米粒度分析仪、扫描电子显微镜和高温黏度测定仪对QI颗粒形貌、粒度及脱除体系黏度进行表征和测定，分析压力对固体颗粒物絮凝沉降的影响规律。研究结果表明，增加压力对沥青收率升高有明显影响，使精制煤焦油沥青的收率由常压的64.6%（质量分数）提升至1MPa时的84.3%（质量分数），精制沥青的QI含量维持在0.06%~0.1%（质量分数）之间。添加15%生物质沥青的混合沥青，产率则由常压时的55.7%（质量分数）提升至1MPa时的72.5%（质量分数）。压力对精制沥青的QI含量影响较小，压力增大，溶剂对沥青组分尤其是重质组分的溶解能力增强，使精制沥青产率升高。较高压力也使体系的黏度略微增大，造成部分QI颗粒沉降困难，不过影响较小。中间相沥青制备的结果表明，精制沥青可以制备出具有流域型结构的中间相沥青，添加生物质沥青更好地改进了流域型的显微结构。

关键词: 溶剂萃取, 沉降, 分离, 热解