The energetic and entropic contributions controlling the orientation of alkyl substituted aromatic molecules in the pores of MFI zeolites
The energetic and entropic contributions controlling the orientation of benzene, toluene and pxylene on acidic (H/ZSM-5) and non acidic (Silicalite-1) MFI type materials were studied using calorimetry to determine the integral uptake and IR spectroscopy for monitoring the individual coverage of the SiOH and SiOHAl groups. The Langmuir model, used to describe the sorption isotherms, indicates the presence of sterically constrained sorption structures, which primarily differ in the decrease of entropy. Energetically the sorption is controlled by the interaction between the molecules and the pore walls, while the localized interaction with the bridging hydroxy groups is only a minor energetic contribution. However, if the molecules are located close to SiOHAl groups perturbed hydroxy groups are formed, their frequency reflects the local constraint of the molecules at the sorption sites.
Andreas Jentys Rino R. Mukti Johannes A. Lercher
Technische Universitat Munchen, Department Chemie, Lichtenbergstr. 4, D-85747 Garching,Germany
国际会议
北京
英文
2007-08-12（万方平台首次上网日期，不代表论文的发表时间）