煤直接液化油中混合酚的分离研究

Separation of mixed phenolic compounds from direct coal liquefaction

利用分子筛择形特点,对煤直接液化油中的混合酚实施高效分离。本研究选取间甲酚和对甲酚作为分离煤直接液化油馏分段混合酚的模型化合物,采用化学液相沉积法对HZSM-5吸附剂的孔口结构进行改变,分析分子筛硅铝比及颗粒粒径对模型化合物间甲酚和对甲酚吸附分离性能的影响,以获得高性能固相吸附剂,并将其应用于180-190℃馏分段混合酚分离。结果表明,当分子筛硅铝比为25、粒径为3-5μm时,分子筛的孔口结构调节效果最优;当正硅酸乙酯的最小用量为0.2 mL/g时,固相吸附剂的吸附量为0.03 g/g,对甲酚选择性高于95%。由于外表面沉积物对吸附剂的孔口结构变化,导致对甲酚选择性的提高。进一步采用HZSM-5(1)吸附剂对真实煤直接液化油混合酚的分离中发现,苯酚和对甲酚的选择性均达到100%。

The shape selection features of molecular sieve were used to efficiently separate the mixed phenols of oil fraction from coal direct liquefaction.In this paper,m-cresol and p-cresol were selected as the model compounds for coal liquified oil fraction.The pore structure of HZSM-5 adsorbent was adjusted by chemical liquid phase deposition method.Influence of ratio of silica to alumina and particle size of molecular sieve on the structural properties after modification were investigated.Considering the modified effect on adsorption and separation properties of cresol and p-cresol,a high-performance solid phase adsorbent was obtained,and was applied to separation of phenols in liquid oil from 180-190℃fraction.The results show that when the molecular sieve has a silica-alumina ratio of 25 and a particle size of 3-5μm,the pore structure adjustment effect of the molecular sieve is optimal.When the minimum amount of tetraethyl orthosilicate is 0.2 mL/g,the adsorption capacity of solid phase adsorption is 0.03 g/g,and the selectivity of p-cresol is greater than 95%.The selectivity to p-cresol is increased due to changes in the orifice regulation of the adsorbent on the outer surface deposits.Furthermore,using modified HZSM-5(1)adsorbent to separate the mixed phenols from real coal direct liquefied oil,the selectivity of phenol and p-cresol reached 100%.