Bidisperse pore diffusion model for zeolite pressure swing adsorption

Journal Article · Mon Jun 01 04:00:00 EDT 1987 · A.I.Ch.E. J.; (United States)

DOI:https://doi.org/10.1002/aic.690330620· OSTI ID:5483157

Doong, S J; Yang, R T

The published theoretical models for pressure swing adsorption (PSA) are of either the equilibrium type, i.e., instantaneous equilibrium is assumed between the gas and adsorbed phases, or the diffusion type considering only a monodisperse pore structure. There is reason for doubt that either type of model is applicable to adsorption processes using zeolite sorbent, which has a bidisperse pore structure. Commercial zeolite sorbents contain crystals of the size 1-9 microns that are pelletized with a binder. Sorption is entirely within the crystals, which contain micropores, whereas the binder contains macropores with a negligible sorption capacity. This paper presents a general PSA model for zeolite sorbents. Both micropore and macropore diffusion are considered. The mathematical complexity of the pore diffusion equations for the two types of pores is reduced by assuming parabolic concentration profiles in both crystals and pellets. Thus the two partial differential equations are converted into ordinary differential equations containing only time derivatives, and the burden of integration along the radial distance is completely eliminated. The model is general enough to be applied to bulk, multicomponent separations using any PSA cycle. The specific separation discussed in this work is the bulk separation of a hydrogen methane mixture using 5A zeolite. The boundary conditions in the model depend on the PSA cycle.

• Research Organization: Dept. of Chemical Engineering, State Univ. of New York, Buffalo, NY 14260
• OSTI ID: 5483157
• Journal Information: A.I.Ch.E. J.; (United States), Journal Name: A.I.Ch.E. J.; (United States) Vol. 33:6; ISSN AICEA
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
080100 -- Hydrogen-- Production
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADSORBENTS
ADSORPTION
ALKANES
CATALYSTS
CRYSTAL STRUCTURE
CRYSTALS
DIFFUSION
ELEMENTS
EQUILIBRIUM
FLUIDS
GASES
HYDROCARBONS
HYDROGEN
HYDROGEN PRODUCTION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MATHEMATICAL MODELS
METHANE
MICROSTRUCTURE
MINERALS
NONMETALS
ORGANIC COMPOUNDS
PELLETS
POROSITY
PRESSURE GRADIENTS
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
ZEOLITES