SINGLE-COMPONENT SORPTION DIFFUSION OF CYCLIC-COMPOUNDS FROM THEIR BULK LIQUID-PHASE IN H-ZSM-5 ZEOLITE/

Single-component sorption/diffusion of cyclohexane, pyridine, benzene, toluene, aniline, ethylbenzene, xylene isomers, n-propyl- and isoprop ylbenzenes, and mesitylene in H-ZSM-5 (Si/Al = 39.7) zeolite from thei r bulk liquid phase at 273-338 K has been measured volumetrically. The diffusivity and activation energy for the diffusion are found to be s trongly influenced by the side groups attached to the benzene nucleus, polarity, critical molecular size, and configuration of sorbate molec ules. However, the influence of configuration and/or flexibility (i.e. , compressibility to the zeolite channel diameter) plays a vital role in controlling/deciding the penetration (Or entry) and configurational diffusion (after penetration) of sorbate molecules in the zeolite cha nnels. The influence of critical size and configuration of sorbate mol ecules, on their entry in the zeolite channel and also their configura tional diffusion after sorption, can be explained by the shuttlecock-s huttlebox model for sorption/diffusion of bulky molecules in medium-po re zeolites. The influence is explained by taking into consideration t he orientations in different conformations and compressibility in the movement in different directions of the sorbate molecules.