Adsorption of p-Xylene and Benzene on Graphite

흑연 표면위의 p-크실렌과 벤젠의 흡착

  • Chang Seihun (Department of Chemistry, Seoul National University) ;
  • Lee Soon Bo (Department of Chemistry, Sung Kyun Kwan University) ;
  • Kim Youn Soo (Department of Chemistry, Seoul National University) ;
  • Ahn Woon-Sun (Department of Chemistry, Sung Kyun Kwan University)
  • Published : 1976.10.30

Abstract

Adsorption isotherms of benzene and p-xylene on both of Spheron 6 (a graphitized carbon black) and Alucer (Alumina) are obtained at various temperatures using a sensitive quartz beam microbalance. From these isotherms BET plots are made to obtain the molecular areas of these adsorbates. On the Spheron 6, the molecular area of p-xylene remains constant until the temperature is increased up to $19^{circ}C$, increases abruptly at $19^{circ}C$ through $19.2^{circ}C$, and then again remains constant thereafter. On the other hand, adsorbed benzene molecules give a quite temperature-independent molecular area. The results are interpreted as the adsorbed p-xylene molecules and benzene molecules are localized on the adsorbents with compact packing, while it gains a hindered-rotational degree of freedom at the expense of vibrational one at the higher temperatures. This peculiar behavior of adsorption is considered as due to the interactions between benzene rings of adsorbents and graphite surface. Molecular areas of these adsorbates on Alucer M. A. increase gradually with temperature, indicating that the adsorbed molecules are unlocalized.

진공미량저울을 써서 Spheron 6 (흑연카아본블랙)와 Alucer M.A. (Alumina) 위에서의 벤젠과 p-크실렌의 흡착등온곡선을 여러 온도에서 얻었다. 이로부터 이 두 흡착질의 흡착분자단면적이 온도에 어떻게 의존하는가를 알아 보았다. 흑연표면에서 p-크실렌은 $19^{circ}C$이하에서 촘촘하게 쌓인 편재흡착을 하고 $19.2^{circ}C$이상의 높은 온도에서는 제한된 회전을 하는 편재흡착을 한다. 이것으로 미루어 보아 벤젠, 및 간단한 벤젠유도체들도 낮은 온도에서는 촘촘하게 쌓인 편재흡착을 하고 높은 온도에서는 제한된 회전을 하는 편재흡착을 일으킨다고 생각된다. 한편 Alucer M.A. 표면에서는 이들 흡착질 분자의 흡착단면적이 온도증가에 따라 점차적으로 증가하여, 이들 흡착질 분자가 편재화되어 있지 않음을 나타내었다.

Keywords

References

  1. Adsorption, Surface Area and Porosity S.J. Gregg;K.S.W. Sing
  2. J. Phys. Chem. v.65 A.A. Isirikyan;A. V. Kiselev
  3. J. Phys. Chem. v.66 A.A. Isirikyan;A. V. Kiselev
  4. J. Phys. Chem. v.66 A.A. Isirikyan;A.V. Kiselev
  5. J. Amer. Chem. Soc. v.72 R. Nelson Smith;Conway Pierce;Herman Cordes
  6. J. Phys. Chem. v.68 Conway Pierce;Bland Ewing
  7. J. Phys. Chem. v.71 Conway Pierce;Bland Ewing
  8. J. Phys. Chem. v.73 Conway Pierce
  9. J. Korean Chem. Soc. v.18 Y. Kim;Y. Ahn;H. Pak;S. Chang
  10. J. Phys. Chem. v.68 A. Bondi
  11. The Nature of the Chemical Bond L. Pauling