The high-purity purification of 2,6-dimethylnaphthalene (2,6-DMN, 10.43 wt%) from the concentrate of DMN isomers recovered from light cycle oil (LCO) through distillation-extraction combination was examined by a crystallization operation. To select the most suitable crystallization solvent for purification of 2,6-DMN, several conventional solvents, which have been employed commercially as crystallization solvents for high-purity performance, were tested, through measurement of purity and yield of 2,6-DMN. The solvents used were acetone, cyclohexanone, ethanol, ethyl ether, ethyl acetate, isopropyl ether, methanol, n-hexane, n-heptane, pyridine, THF, toluene, and a mixture of methanol and acetone. The mixture of 60 vol% methanol and 40 vol% acetone (M/A = 1.5) was found to be suitable for purification of 2,6-DMN in the concentrate of DMN isomers based on purity and yield. Increasing the operation temperature and the volume ratio of solvent (M/A = 1.5) to feed (concentrate of DMN) resulted in improving the purity of 2,6-DMN, whereas the yield decreased. The crystal recovered by crystallization run using the concentrate of DMN isomers contained about 76 wt% 2,6-DMN. Furthermore, for recovery of high-purity 2,6-DMN, crystal containing 76 wt% 2,6-DMN was crystallized. As a result, crystal with 99.7 wt% 2,6-DMN was recovered with 40% yield.

증류-추출의 조합에 의해 접촉분해경유(LCO)로부터 회수한 dimethylnaphthalene (DMN) 이성체 농축액을 원료로 사용하여 결정화조작을 행해 2,6-DMN의 정제를 검토했다. 2,6-DMN의 정제에 적합한 용매의 선정을 위해 13종의 용매(acetone, cyclohexanone, ethanol, ethyl ether, ethyl acetate, isopropyl ether, methanol, n-hexane, n-heptane, pyridine, THF, toluene, methanol과 acetone의 혼합용매)를 사용하여 결정화조작을 행한 결과, 60 vol% methanol과 40 vol% acetone의 혼합용매(M/A = 1.5)가 2,6-DMN의 순도 및 수율의 측면에서 우수한 정제성능을 보였다. 결정화 온도의 상승 및 용매(M/A = 1.5)/원료(농축액)의 체적비의 증가는 2,6-DMN의 순도를 향상시켰으나, 역으로 수율의 저하를 초래시켰다. DMN 이성체 농축액을 원료(10.43 wt% 2,6-DMN)로 사용한 결정화를 통해 회수한 결정(76 wt% 2,6-DMN)을 원료로 사용하여 재차 결정화조작을 행한 결과, 40%의 수율로 99.7 wt% 2,6-DMN의 결정을 얻을 수 있었다.