(687a) Probing Metal-Organic Framework (MOF) Design for Adsorptive Sour Natural Gas Purification

Authors: 
Joshi, J., Georgia Institute of Technology
Zhu, G., Georgia Institute of Technology
Lee, J., Georgia Institute of Technology
Carter, E., Georgia Institute of Technology
Lively, R., Georgia Institute of Technology
Jones, C. W., Georgia Institute of Technology
Walton, K. S., Georgia Institute of Technology
Parent and amine-functionalized analogues of the metal-organic frameworks (MOFs) UiO-66(Zr), MIL-125(Ti), and MIL-101(Cr) were evaluated for their hydrogen sulfide (H2S) adsorption efficacy and post-exposure acid gas stability. Adsorption experiments were conducted through fixed-bed adsorption breakthrough studies, utilizing multicomponent 1% H2S/99% CH4 and 1% H2S/10% CO2/89% CH4 test gases as simplistic representative sour gas mixtures. Pelletized MIL-101(Cr) adsorbents were found to be unstable through diffraction and porosity measurements following H2S exposure, while other materials retained their characteristic properties. Linker-based amine functionalities increased H2S breakthrough times and saturation capacities from their parent MOF analogues. Competitive CO2 adsorption effects were mitigated in mesoporous MIL-101(Cr) and MIL-101-NH2(Cr), in comparison to microporous UiO-66(Zr) and MIL-125(Ti) frameworks. This result suggests the installation of H2S binding sites in large pore MOFs could potentially enhance H2S selectivity. In-situ FTIR measurements in 10% CO2 and 5000 ppm H2S environments illustrate framework hydroxyl and amine moieties serve as selective H2S physisorption sites. Results from this study elucidate design strategies and stability considerations for engineering MOFs in sour gas purification applications.