PREPARATION AND EVALUATION TECHNIQUES OF POROUS MATERIALS AND MIXED MATRIX MEMBRANES FOR TARGETED CO2 SEPARATION APPLICATIONS

Author

Tsemre TessemaFollow

DOI

https://doi.org/10.25772/Y0BQ-K948

Defense Date

2017

Document Type

Thesis

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Prof. Hani M El-Kaderi

Abstract

The use of porous sorbents for physisorptive capture of CO₂ from gas mixtures has been deemed attractive due to the low energy penalty associated with recycling of such materials. Porous organic polymers (POPs) have emerged as promising candidates with potential in the treatment of pre- and post- fuel combustion processes to separate CO₂ from gas mixtures. Concurrently, significant advances have been made in establishing calculation methods that evaluate the practicality of porous sorbents for targeted gas separation applications. However, these methods rely on single gas adsorption isotherms without accounting for the dynamic gas mixtures encountered in real-life applications. To this end, the design and application of a dynamic gas mixture breakthrough apparatus to assess the CO₂ separation performance of a new class of heteroatom (N and O) doped porous carbons derived from a Pyrazole precursor from flue gas mixtures is presented.

Here in, two new benzimidazole linked polymers (BILPs) have been designed and synthesized. These polymers display high surface while their imidazole functionality and microporous nature resulted in high CO₂ uptakes and isosteric heat of adsorption (Q_st). BILP-30 displayed very good selectivity for CO₂ in flue gas while BILP-31 was superior in CO­₂ separation from landfill gas mixtures at 298 K and 1 bar. Additionally, a new POP incorporating a highly conjugated pyrene core into a polymer framework linked by azo-bonds is presented. Azo-Py displays a nanofibrous morphology induced by the π-π stacking of the electron rich pyrene core. Due to its high surface area and microporous nature, Azo-Py displays impressive CO₂ uptakes at 298 K and 1 bar. Evaluation of the S value for CO₂ separation of Azo-Py revealed competitive values for flue gas and landfill gas at 298 K and 1 bar.

Finally, a highly cross-linked benzimidazole linked polymer, BILP-4, was successfully incorporated into Matrimid^® polymer to form a series of new mixed matrix membranes. The surface functionality of BILP-4 was exploited to enhance the interaction with Matrimid^® polymer matrix to produce robust MMMs which displayed significantly improved CO₂ gas permeabilities and ideal selectivities for CO₂/N₂.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

8-11-2017