abstract: Membrane technology is a viable option to debottleneck distillation processes and minimize the energy burden associated with light hydrocarbon mixture separations. Zeolitic imidazolate frameworks (ZIFs) are a new class of microporous metal-organic frameworks with highly tailorable zeolitic pores and unprecedented separation characteristics. ZIF-8 membranes demonstrate superior separation performance for propylene/propane (C3) and hydrogen/hydrocarbon mixtures at room temperature. However, to date, little is known about the static thermal stability and ethylene/ethane (C2) separation characteristics of ZIF-8. This dissertation presents a set of fundamental studies to investigate the thermal stability, transport and modification of ZIF-8 membranes for light hydrocarbon separations. Static TGA decomposition kinetics studies show that ZIF-8 nanocrystals maintain their crystallinity up to 200○C in inert, oxidizing and reducing atmospheres. At temperatures of 250○C and higher, the findings herein support the postulation that ZIF-8 nanocrystals undergo temperature induced decomposition via thermolytic bond cleaving reactions to form an imidazole-Zn-azirine structure. The crystallinity/bond integrity of ZIF-8 membrane thin films is maintained at temperatures below 150○C. Ethane and ethylene transport was studied in single and binary gas mixtures. Thermodynamic parameters derived from membrane permeation and crystal adsorption experiments show that the C2 transport mechanism is controlled by adsorption rather than diffusion. Low activation energy of diffusion values for both C2 molecules and limited energetic/entropic diffusive selectivity are observed for C2 molecules despite being larger than the nominal ZIF-8 pore aperture and is due to pore flexibility. Finally, ZIF-8 membranes were modified with 5,6 dimethylbenzimidazole through solvent assisted membrane surface ligand exchange to narrow the pore aperture for enhanced molecular sieving. Results show that relatively fast exchange kinetics occur at the mainly at the outer ZIF-8 membrane surface between 0-30 minutes of exchange. Short-time exchange enables C3 selectivity increases with minimal olefin permeance losses. As the reaction proceeds, the ligand exchange rate slows as the 5,6 DMBIm linker proceeds into the ZIF-8 inner surface, exchanges with the original linker and first disrupts the original framework’s crystallinity, then increases order as the reaction proceeds. The ligand exchange rate increases with temperature and the H2/C2 separation factor increases with increases in ligand exchange time and temperature. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2017

The increase in unconventional shale gas extraction in Pennsylvania has resulted in an increased number of groundwater contamination claims. Well water quality was investigated in southern Butler County, PA where 387 unconventional gas wells have been drilled since 2006. A total of 121 households participated in a survey and 238 well water samples were tested. Specific conductivity, pH, and dissolved oxygen in these samples were measured in the field and seven anion concentrations and thirty metal concentrations were measured in the lab. A subset of 91 water wells was also tested for light hydrocarbons (methane, ethane, ethylene, propylene, propane, butane). Pennsylvania DEP file reviews were used to create GIS maps indicating legacy oil and gas, unconventional wells, and plot water testing results. Results indicate few wells had high quality groundwater, with 86% containing one or more contaminants above (secondary) Maximum Contaminant Levels, with manganese (56%), iron (47%), fluoride (18%), TDS (18%), pH (17%), aluminum (17%) the most common. / Bayer School of Natural and Environmental Sciences; / Environmental Science and Management (ESM) / MS; / Thesis;