Faujasite type zeolites were synthesized from kaolin minerals. K,Ca,Sr, and Ba zeolite were prepared by ion exchange with its chloride salts solution respectively. Selective adsorption of xylene isomers has been investigated by adsorbing xylene isomers over a series of the zeolites and desorbing them with toluene. The highest selectivity was obtained with Ba zeolites, developing for para xylene are : 3.11 relative to ortho xylene, 3.58 to meta xylene, and 2.24 to ethyl benzene. Effect of adsorption temperature and control of water content of Ba zeolites was quite important. The optimum adsorption and activation temperature was at 125℃ and 180℃, respectively. A much higher selectivity was obtained with a binary stream than a ternary stream. It was also found that the selectivity increased with increasing degree of ion exchange.
It may be thought that the principal reason of selective adsorption is due to molecular sieve effect caused by the size and shape differences between the adsorbate molecule and crystal aperture.
K, Ca, Sr 및 Ba로 이온교환한 합성 Faujasite형 제올라이트에 크실렌 이성체를 흡착시키고 다시 톨루엔으로 탈착시키므로서 크실렌 이성체간의 Selective Adsorption 을 조사하였다. Ba으로 이온 교환한 제올라이트가 가장 큰 Selectivity 를 나타내고 Para Xylene 을 기준으로 Ortho Xylene 에 대하여 3.11, Meta Xylene에 대하여 3.58, Ethyl Benzene에 대하여 2.24 이었다. 또한 Selectivity는 Ternary Stream일때보다 Binary Stream 일 때가 더 큰 Selectivity 를 나타냈다. 흡착온도와 Activation 온도가 Selectivity 에 영향을 미쳤고 Optimum Condition은 각각 125℃, 180℃ 일 때 이었다. 또한 Selectivity는 Ba의 이온교환정도가 증가할수록 점차 증가되었다.
크실렌 이성체의 Selective Adsorption은 주로 크실렌 이성체의 분자 크기와 이온교환된 제올라이트의 유효 세공크기로 부터 생기는 Molecular Sieve Effect에 기인하는 것으로 생각된다.
