Self-diffusion in zeolites is studied using a simple mean-field theory and dynamic Monte-Carlo simulations of diffusion on a lattice model of the zeolite pore space. Our method is powerful, because of its simplicity, flexibility and ability to study the influence of various factors: the topology of the pore network, the fraction of strong adsorption sites, the relative strengths of weak and strong sites, the number of sites per zeolite cage, and the ratio of intracage to extracage hopping probabilities. Notwithstanding the simplicity of the modeling, our results confirm the qualitative trends observed in pulsed-field gradient NMR experiments, and are able to explain them. For ZSM-5, we also found a new possible type of functional dependency of the diffusivity on occupancy, with two inclination points.
|Number of pages||9|
|Journal||Chemical Engineering Science|
|State||Published - Jul 1999|
|Event||Proceedings of the 1998 15th International Symposium on Chemical Reaction Engineering, ISCRE 15 - Newport Beach, CA, USA|
Duration: 13 Sep 1998 → 16 Sep 1998
Bibliographical noteFunding Information:
This work was supported by the O$ce of Industrial Technology of the US Department of Energy under contract DE-AC03-SF7600098. A Fellowship from the Belgian American Educational Foundation, a Fellowship as an &&Aspirant’’ from the FWO (Fund for Scienti"c Research } Flanders, Belgium) and a FWO}NSF grant for the "rst stages of this project are gratefully acknowledged. Continued funding of this project was provided by a Postdoctoral Fellowship from the Fund for Scient-i"c Research } Flanders, Belgium (FWO). We thank Professor Vijay T. John for sending us a copy of the Ph.D. thesis of his former student, John H. Scogin.
- Lattice model