HWAHAK KONGHAK, Vol.23, No.2, 109-115, April, 1985
NaY 상에서 몇가지 방향족 탄화수소의 흡착특성
Adsorptive Characteristics of Sodium Y Zeolite for Some Aromatic Hydrocarbons
초록
Sodium Y zeolite와 benzene, toluene, ethylbenzene, xylenes과 같은 방향족 탄화수소가 이루는 흡착계에 대한 흡착특성을 온도범위 140∼280 ℃에서 Gas chromatography를 사용하여 연구하였다. 또한 cyclohexane, n-pentane 그리고 n-pentene에 대해서도 조사, 비교하였다. Benzene 유도체에 대한 흑착은 흡착량에 따른 흡착열이 증가하는 것으로 보아 NaY에서 균일한 흡차계를 갖고 있는 것으로 판단되며 흡착량과 흡착열은 알킬기의 직환정도에 따라 증가하였고 이온화 포텐셜이 증가할수록 초기흡착열은 감소함을 보였다. 이 흡착계에 세공의 충진개념을 도입한 Dubinin-Astarkhov식을 적용시켜 본 결과 n-pentane과 cyclohexane계가 비교적 잘 적용되었으며 n-pentene과 benzene 유도체는 상당한 편차를 보여주었다. 또 Sodium Y와 같이 세공이 큰 구조를 갖고 있는 zeolite에서는 흡착분자크기의 영향보다는 π전자와 알킬기의 영향이 더 큼을 확인하였다.
The adsorptive characteristics of sodium Y zeolite for simple aromatic hydrocarbons, such as benzene, toluene, ethylbenzene, xylenes were investigated by means of gas chromatography at 140 to 280 ℃．For comparison, the adsorptive characteristics made from the isotherm curves, previously published, for cyclohexane, n-pentane and n-pentene on NaY zeolite were also checked. Sodium Y zeolite seems to form a homogeneous system for aromatic compounds. The amount adsorbed and the adsorption heat for benzene derivatives increase with the extent of alkyl substitution.
A linear relationship was confirmed between the decrease in the ionization potential of aromatic hydrocarbons and the increase in the initial heat of adsorption.
The Dubinin-Astarkhov's equation based on the Polanyi's theory was also applied on the adsorption system. The Dubinin-Astarkhov's equation was fitted well for cyclohexane and n-pentane but not for benzene derivatives and n-pentene. It was found that the adsorption with regard to the large pore zeolite such as sodium Y was preferably affected by the electrons and the extent of alkyl substitution rather than the kinetic diameter of adsorbate.
A linear relationship was confirmed between the decrease in the ionization potential of aromatic hydrocarbons and the increase in the initial heat of adsorption.
The Dubinin-Astarkhov's equation based on the Polanyi's theory was also applied on the adsorption system. The Dubinin-Astarkhov's equation was fitted well for cyclohexane and n-pentane but not for benzene derivatives and n-pentene. It was found that the adsorption with regard to the large pore zeolite such as sodium Y was preferably affected by the electrons and the extent of alkyl substitution rather than the kinetic diameter of adsorbate.