影响煤焦油沥青质测定量的工艺参数

Effect of process parameters on determination of asphaltene from coal tar

煤焦油通过溶剂分析可定量分离为三部分:甲苯不溶物、沥青质和油相。本文主要研究了煤焦油在此分离过程中芳烃溶剂类型、萃取方法、甲苯溶液浓缩量、烷烃溶剂类型和正庚烷溶剂与甲苯溶液浓缩量的添加比例对煤焦油沥青质沉淀量的影响。结果表明,甲苯溶液浓缩量、正庚烷与甲苯溶液浓缩量的添加比例对沥青质沉淀量的影响较大,萃取方法次之,将苯替换成甲苯影响最小。当选择甲苯溶解煤焦油,超声萃取3h,甲苯溶液浓缩量9mL,正庚烷与甲苯溶液浓缩液的添加比例为20∶1时,煤焦油沥青质的沉淀量为13.4%。本实验表明煤焦油的分离工艺会影响沥青质沉淀量,故在研究煤焦油沥青质性质和结构时需注明沥青质的沉淀分离条件。

Solvent analysis is a method for quantitative separation of coal tar into toluene insoluble, asphaltene （toluene soluble,pentane insoluble）,and oil （pentane soluble）. The prime objective was to identify the variables in the procedure,including aromatic solvent type,extraction method,amount of toluene solution concentrate （degree of toluene boil-off） ,alkane solvent type,and ratio of n-heptane to toluene solution concentrate that affected the precipitate obtained for asphaltene content. Substitution of toluene with benzene and extraction method did not have a large effect on the precipitate reported for asphaltene. Heptane was chosen as alkane solvent instead of pentane. However amount of toluene solution concentrate and ratio of n-heptane to toluene solution concentrate did have a large effect on the precipitate reported as asphaltene. Coal tar from northern Shaanxi province was tested. With the suitable time of ultrasonic extraction for 3 hours,toluene solution concentrate of 9mL,a 20-fold of n-heptane over toluene solution concentrate,the asphaltene precipitate determined was 13.4%. The separation conditions of asphaltene determination should be indicated when studying the properties and structure of asphaltene from coal tar,since the coal tar separation technique have a large effect on asphaltene precipitated.