PNNL

Abstract

The continued integration of technology capable of achieving higher degrees of sustainability while meeting global material and energy demands is of singular importance in halting human-caused climate change. Unit operations of gas separations membranes composed of metal-organic frameworks (MOFs) are considered promising candidates owing to their modular, scalable nature and high degree of tunability required to maintain separation functionality. However, both an evaluation of MOF materials and an intensive examination of MOF-gas molecule interactions are necessary to fully understand the fundamental separation criteria as well as define suitable ranges of gas separations applications. Herein, we present our findings on the greenhouse gas separations capabilities of hydrophilic, Al-based MIL-160 in the selective uptake of carbon dioxide (CO2) from other relevant greenhouse gases methane (CH4), sulfur dioxide (SO2), nitrogen dioxide (NO2), and nitric oxide (NO)—including gravimetric solubility, permeability, and diffusivity calculations. We have found that a MIL-160 membrane has excellent applicability in the separation of gases with varying electronegativities, noting diffusivity selectivities of 72.0, 9.53, and 13.8 for CH4, NO2, and NO, respectively, relative to CO2 at 50 bar. Further, our analysis demonstrates that the selectivity at which gas molecules diffuse through the MIL-160 membrane varies strongly with simulation pressure, suggesting that MIL-160 is a potentially ideal candidate for the development of pressure-swing adsorption processes that perform gas separations efficiently while mitigating emissions of greenhouse gases.