Date of Award

Spring 1994

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering - (Ph.D.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Kamalesh K. Sirkar

Second Advisor

Henry Shaw

Third Advisor

Piero M. Armenante

Fourth Advisor

Demetri P. Petrides

Fifth Advisor

Jay N. Meegoda

Abstract

The behaviors of different membrane modules for the selective removal and recovery of water vapor and some volatile organic compounds (VOCs) from N2 have been studied. For the selective permeation-based removal of water vapor from N2, a polymeric water-swollen gel membrane in the form of Cuprophan hollow fiber was employed. A thin film composite type rubbery membrane module was studied for the selective removal of VOCs like toluene or methanol from N2 by permeation. The usefulness of pore-condensation phenomenon-based removal of toluene or xylene from N2 was explored using a microporous ceramic tubular membrane.

The experimental performance of Cuprophan hollow fiber membrane module was studied for the permeation removal of water vapor from N2. A simple model was developed taking into account the observed exponential dependence of moisture permeance on relative humidity. Water vapor was removed continuously and efficiently through the Cuprophan hollow fiber membrane; the experimentally obtained performances were well described by the model. The membrane showed considerable selectivity for water vapor over N2 and water vapor over toluene vapor.

Short hollow fiber modules employing an ultrathin nonporous silicone coating membrane on a porous substrate were found to be extremely productive in removing toluene or methanol from N2 at atmospheric pressure by an applied permeate-side vacuum. Removal of 90-99 % of VOC was achieved at low feed gas flow rates over a wide range of VOC concentrations. The membrane exhibited high selectivities for the VOC over N2; VOC permeance was extremely concentration-dependent.

Selective removal of toluene or xylene from N2 via pore-condensation in a microporous tubular ceramic membrane having 50 A pores was not found to be as efficient. This is likely to be due to the difficulty of achieving pore condensation in larger pores and at lower VOC partial pressures.

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