Separation of mixed phenolic compounds from direct coal liquefaction

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 3-5 μm, 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%.