Adsorption in microporous adsorbents: Thermodynamics and computer simulations.

Format:

Book

Thesis/Dissertation

Author/Creator:

Karavias, Fokion.

Contributor:

Myers, Alan L., 1932- advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Chemical engineering.

Chemistry, Physical and theoretical.

0494.

0542.

Penn dissertations--Chemical engineering.

Chemical engineering--Penn dissertations.

Local Subjects:

Penn dissertations--Chemical engineering.

Chemical engineering--Penn dissertations.

0494.

0542.

Physical Description:

352 pages

Contained In:

Dissertation Abstracts International 53-05B.

System Details:

Mode of access: World Wide Web.

text file

Summary:

The primary goal of this thesis is to apply thermodynamic, statistical mechanical and computer simulation methods to describe the equilibrium behavior of single-gases and mixtures confined in microporous adsorbents. Models capable of handling the effects of energetic heterogeneity and adsorbate-adsorbate interactions were developed and studied. The ultimate objective is to predict equilibrium properties of adsorbed molecules.

A gravimetric procedure is proposed for measuring equilibrium adsorption from gas mixtures. The model developed here, a Bragg-Williams approximation for the local isotherm and a Beta distribution of adsorptive energies, provides a consistent framework for the rigorous thermodynamic equations that govern adsorption equilibrium for gas mixtures. The composition of the adsorbed phase was calculated from the gravimetric data using the principles of adsorption thermodynamics. The increased computational work is more than compensated for by a reduction in experimental effort.

Grand canonical Monte Carlo simulations were performed for single-gas and binary adsorption of Lennard-Jones molecules with point multipole moments in zeolite cavities of type X. A spherically-averaged potential was adopted for the dispersion and repulsion interaction of adsorbate molecules with the adsorbent. The induced electrostatic potential and the interactions of the point multipole moments with the electric field generated by the zeolite cations were taken into account. Thermodynamic and structural properties have been calculated for Xe, CH$\sb4,$ CO$\sb2,$ C$\sb2$H$\sb4,$ and i-C$\sb4$H$\sb{10}$ and their binaries in zeolite 13X.

Adsorption isotherms, phase diagrams, isosteric heats and structural properties were evaluated and compared with experiment. The results reveal the importance of adsorbate-adsorbate interactions for sorption in faujasite. Density and energy distributions show that the cavity is either a relatively homogeneous surface or a highly heterogeneous one, depending on the molecular characteristics of the adsorbed gas and the type, position and charge of the zeolite cations. Monte Carlo simulations gave good agreement with experiment for two mixtures (C$\sb2$H$\sb4$-CO$\sb2$ and CO$\sb2$-CH$\sb4)$ but there were discrepancies between simulation and experiment for the system i-C$\sb4$H$\sb{10}$-C$\sb2$H$\sb4.$

Notes:

Thesis (Ph.D. in Chemical Engineering) -- Graduate School of Arts and Sciences, University of Pennsylvania, 1992.

Source: Dissertation Abstracts International, Volume: 53-05, Section: B, page: 2434.

Supervisor: Alan L. Myers.

Local Notes:

School code: 0175.

Access Restriction:

Restricted for use by site license.