Electronic Theses and Dissertations

Date of Award

2012

Document Type

Dissertation

Degree Name

M.S. in Engineering Science

Department

Chemical Engineering

First Advisor

Paul Scovazzo

Second Advisor

Peter Sukanek

Third Advisor

John O'Haver

Abstract

Renewable fuels are heavily researched due to the increasing price of and resulting pollution from fossil fuels. The production of useable energy from waste—animal, sewage, discarded food, landfill matter would be a valuable renewable fuel production method. Biogas is a renewable fuel that is produced by anaerobic digestion, composed mainly of methane, carbon dioxide and small percentages of hydrogen sulfide and water vapor. Before this biogas—predominately bio-methane—can be converted to fuel, it must be dehumidified to become useable. Typically membrane-based gas dehumidification uses hydrophilic polymer membrane materials, such as polydimethylsiloxane (PDMS) and cellulose acetate (CA). The main problems with polymer dehumidification membranes are methane loss and the susceptibility of polymer materials to plasticization by H2O [6]. Water vapor does not plasticize room temperature ionic liquid membranes (RTIL-membranes) according to literature data, and RTIL-membranes have water/CH4 selectivities > 6000. In this paper we will build on the initial literature RTIL-dehumidification data by looking at a series of ammonium and imidazolium-based ionic liquids. One membrane based on the trifluoromethanesulfonate [TfO] anion had a water permeance of 2000 GPUs with a H2O/CH 4 selectivity of 16000. The bulk of the RTILs exhibited similar water permeances ranging from ∼700-900 GPU. The methane permeances ranged from 0.15 GPU–0.5 GPU with [emim][TfO] having the lowest average CH 4-permeance. The data collected was for membranes with approximately 135 mm active film thickness. Even with these relatively thick active film layers, the water vapor separation performances of the RTIL membranes are on par with current polymer membranes.

Concentration/Emphasis

Emphasis: Chemical Engineering

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