| Low temperature coal tar is a by-product of coal pyrolysis process, the composition of low temperature coal tar is extremely complicated and contains many high-value compounds. Howeve the unique physicochemical property of coal tar makes it very hard to have a fine speration by using normal separation process. This research was mainly focused on a solvent extraction combined with column chromatography prossess to recovery phenolic compunds from low temperature coal tar, and use the resins material which is widely used in water treatment as the stationary phase.Firstly, in order to remove the heavy component from low temperature coal tar, by using the n-heptane extraction, the n-heptane soluble fraction was obtained, then the n-heptane soluble fraction was sperated on the resin column to produce neutral oil and polar oil.For this purpose, the absorption capacity of resin materal was evaluated. Considering thar the sbsoption mechanism was different when it happens in oil or non-polar phase, the isotherms for phenol in n-heptane solution was measured on sulfonate polystyrene(SPS) and carboxylic ester(XAD-7). The result suggests hydrogen bonding to be a major mechanism for the sorption of phenol from nonpolar solvents. Parameters from the four isotherm models and the thermodynamic parameters indicated that the absorption process for resins was spontaneous, non-ideal, physical and exothermic.The carboxylic ester(XAD-7) which have higer obsorption capacity was choose to separate low temperature coal tar n-heptane soluble fraction as the stationary phase on column chromatography. By using the n-heptane and ethyl acetate as mobile phase, the neutral oil fraction and polar oil fraction were eluted. The GC-MS analysis shown that phenolic compounds content was 95.2wt.% in polar oil fraction. For the resins partical size was larger than silica-gel, the elution rate was higher than on silica-gel column, that could increase the sparation efficiency. |
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