Abstract:

This study was to achieve selective separation of specific aromatic hydrocarbons from low temperature coal tar. The feedstock was pretreated to separate phenols and enrich specific aromatic hydrocarbons, and then extracted by multiple solvents to separate selectively aromatic and non-aromatic hydrocarbons. The extraction conditions were optimized by the theory of Hansen solubility parameter. Selectivity of the extraction process was enhanced with the rise of Hansen solubility distance (R_a), while dissolving capacity decreased with the increase of R_a. The multiple solvents suggested in the study were dimethyl formamide (DMF)+6% water (volume fraction), and the optimized extraction condition was 25℃ and solvent/oil ratio of 6:1. The raffinate was extracted repeatedly under the optimized condition to collect residual aromatic hydrocarbons. The extract was extracted by formamide repeatedly to increase the concentration of aromatics and separate heterocyclic compounds and other polar components. Consequently, the mass percentage of aromatic hydrocarbons in the product was ca. 95% and the total yield of aromatics was ca. 94%; phenols, non-aromatics and other polar components were also separated selectively from the feedstock. The extraction solvent of aromatics was recovered by reduced pressure distillation, which was stable during the extraction and recycle process.

Key words: low temperature coal tar, separation, extraction, solubility, Hansen solubility parameter

摘要：

以研究低温煤焦油中特定芳烃组分的选择性分离为目标, 通过预处理分离酚类化合物和富集特定芳烃组分, 采用多元溶剂萃取方法选择性分离芳烃和非芳烃组分, 采用Hansen溶度参数理论进行多元溶剂的设计和萃取条件的优化。结果表明, 溶剂对原料焦油的选择性随Hansen溶度参数“距离”(R_a)增加而增大, 萃取能力则相反。研究得到的多元萃取剂是含水量为体积分数6%的N,N-二甲基甲酰胺溶液, 优化萃取条件是温度25℃、剂/油比6:1。萃余物经多次萃取进一步分离芳烃组分, 萃出物经甲酰胺多次萃取以分离出杂环化合物和极性组分。芳烃组分在最终分离产物中的质量分数为94%, 其总萃取收率为95%。另外非芳烃化合物、杂环化合物和其他极性组分也在本过程中得到了有效富集。

关键词: 低温煤焦油, 分离, 萃取, 溶解性, Hansen溶度参数