Date of Award

2019

Degree Type

Thesis

Degree Name

Master of Science in Chemical Engineering

Department

Washkewicz College of Engineering

First Advisor

Orhan Talu

Subject Headings

Chemical Engineering

Abstract

Metal organic frameworks (MOFs) are nano-porous solids with potential applications in a wide range of fields including gas separation and catalysis. A number of metal organic frameworks show structural transformation and exceptional flexibility on changing the temperature, pressure and adsorption of certain guest molecules. On the contrary, most of the porous solids like zeolites and activated carbon used in applications are rigid. The structural flexibility makes MOF materials very interesting to study and show promise in applications such as sensors, actuators, membrane separation and adsorptive separation. In this study, we examine the chemical potential difference (Δμ) of MIL-53 (Al), a MOF which exhibits a “breathing” phenomena by transitioning between its narrow pore (np) and large pore (lp) conformation. It is important to measure Δμ between the two phases of the solid to be able to predict and/or model gas adsorption. Single component adsorption equilibria of carbon dioxide (CO2), methane (CH4), nitrogen (N2) and oxygen (O2) were measured over a pressure range of 0-20 bar at 273K, 293K and 306K, using a magnetic suspension microbalance. The adsorption measurements show that experimental sample of MIL-53(Al) behaves differently in case of CO2 when compared with other gases. The data obtained is used to investigate these differences in the adsorption characteristics of narrow pore and large pore phases. A modified form of Langmuir model is fitted to the experimental data and corresponding chemical potential differences between the two pore conformations is determined. The effect of temperature dependency is also investigated.

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