Porous Aromatic Frameworks Impregnated with Lithiated Fullerenes for Natural Gas Purification

Natural gas, a lower emission alternative than its fossil fuel counterparts, requires the removal of carbon dioxide, known as sweetening, prior to its use. In this study we computationally explore the separation of methane and carbon dioxide using a new adsorbent consisting of lithium-decorated fullerenes (Li6C60) impregnated within a series of porous aromatic frameworks (PAFs) of various pore sizes. The strong affinity of CO2 with the impregnated frameworks, confirmed by density functional theory, leads to selective adsorption over CH4. The impregnation can also double the CO2 adsorption capacity compared to the bare PAF and increase selectivity of CO2/CH4 up to 48 for an optimum amount of Li6C60, which is above the current industry benchmark. Overall, the study reveals physical insights and proposes impregnated PAFs to be promising candidates for CO2/CH4 separations for natural gas purification.