| Summary: | 碩士 === 長庚大學 === 化工與材料工程研究所 === 97 === Distillative freezing (DF) is a new separation technique to separate mixtures of volatile compounds. Basically, the DF process is operated at triple point condition, in which the liquid mixture is simultaneously vaporized and crystallized due to the three-phase equilibrium. It results in the formation of pure solid, and both liquid phase and vapor phase of mixtures. In essence the process can be continued until the liquid phase is completely eliminated and only the pure solid crystals remain in the feed.
There are two parts in this study. Firstly, the DF process is applied to separate the binary mixture of p-cresol and 2,6-dimethylphenol. Secondly, DF is introduced to purify p-cresol and o-cresol from the quaternary mixture consisting p-cresol, m-cresol, o-cresol and 2,6-dimethylphenol. The experimental results show that p-cresol and 2,6-dimethylphenol can be purify from 85 wt% to 95 wt%, or from 90 wt% to 99 wt% in the binary mixture of p-cresol and 2,6-dimethylphenol. The recovery rate ranges from 10% to 73% depending on the operating temperature and pressures. In the quaternary mixture, p-cresol can be purified from 90 wt% to 98 wt% and o-cresol can be purified from 90 wt% to 95 wt%. A lower recovery rate ranging from 5% to 22% is found.
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