Simulation of diffusion in zeolitic structures

Journal Article · Wed Nov 01 04:00:00 EST 1995 · AIChE Journal

DOI:https://doi.org/10.1002/aic.690411107· OSTI ID:131889

Using Maxwell-Stefan equations, experimental and computational results of binary diffusion in pore- and cage-type zeolitic structures are described. In the generalized Maxwell-Stefan (GMS) formulation, The Fick diffusivity is written as the product of two separate contributions, the GMS or corrected diffusivity and the thermodynamic factor. The concentration dependence of the GMS diffusivity for one- and two-component diffusion in zeolitic structures is investigated. From the Maxwell-Stefan equations, different models for the Fick diffusion coefficient matrix for the description of binary mass transport in molecular sieve materials are derived. Various models used predict binary diffusion in zeolitic structures. Fist, theoretical predictions of binary apparent diffusivities as a function of the occupancy are compared to results from Monte Carlo simulations. Second, theoretical results of binary uptake profiles are compared to experimental results for the system ethylbenzene/benzene/ZSM-5. For different zeolitic structures, that is, pore- and cage-type structures, results of the Monte Carlo simulations agree well with the theoretical predictions. In cage-type structures, the effect of counter exchange between sorbed molecules is demonstrated. Experimental results of transient uptake profiles of a mixture of benzene and ethylbenzene in ZSM-5 follow predictions of the theoretical single-file diffusion model.

• Sponsoring Organization: USDOE
• OSTI ID: 131889
• Journal Information: AIChE Journal, Journal Name: AIChE Journal Journal Issue: 11 Vol. 41; ISSN 0001-1541; ISSN AICEAC
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALKYLATED AROMATICS
BENZENE
BINARY MIXTURES
DIFFUSION
MASS TRANSFER
MATHEMATICAL MODELS
MOLECULAR SIEVES
PERMEABILITY
ZEOLITES