Nitrous Oxide Adsorption and Separation Using CPO-27 Metal-Organic Frameworks

Abstract

Nitrous oxide N2O is a potent greenhouse gas with a high global warming potential approximately 300 times that of carbon dioxide on a 100-year timescale. In addition, it is the leading ozone-depleting substance emitted in the 21st century. The capture of N2O from industrial point sources or from air might therefore become important for environmental protection. Non-point sources such as synthetic fertilizer and manure are the dominant N2O emission sources, while the largest industrial contributors to N2O emission are production of adipic acid and nitric acid. Metal-organic frameworks (MOFs) might be promising materials for the capture of N2O. MOFs are relatively new members of the porous materials family. Due to their interesting properties such as large pore volume, large surface area, and structural regularity these materials gained remarkable interest in the eld of porous materials. Interaction of these materials with greenhouse and energy carrier gases are being extensively investigated for gas storage and separation processes. However, adsorption of N2O on MOFs has only rarely been investigated. This thesis presents a comparative study of the N2O adsorption on a series of isostructural MOFs known as CPO-27 to evaluate their potential for use in separation processes involving N2O. The N2O adsorption properties of the CPO-27-M (M = Mg, Mn, Co, Ni, Cu, and Zn) materials at room temperature were investigated and selectivities for N2O/N2 separation were derived using the ideal adsorbed solution theory. In addition, a detailed structural study was performed by variable-temperature (298 to 185 K) powder synchrotron X-ray diffraction to identify the N2O adsorption sites of the framework and monitor the structural changes that occur during the N2O adsorption.