CARBON DIOXIDE REMOVAL FROM NATURAL GAS USING NANOPOROUS ORGANIC POLYMERS

摘要

There has been considerable interest in the development of newntechnologies and materials that allow CO2 removal from natural gasnwhich is typically contaminated with over 40% CO2 and N2.1 Thenremoval of CO2 would increase the energy density of natural gasnmaking its storage and transpiration more efficient, and enhances itsnconversion to hydrogen fuel. Given the relatively small and similarnkinetic diameter of CH4 and CO2 molecules, their efficient separationnremains a nontrivial task. Among the emerging methods fornaddressing these environmental and economical challenges is the usenof porous materials such as metal organic frameworks (MOFs)1,2 andnnanoporous organic polymer networks3 as CO2 adsorbents in whichnthe precise control over materials chemical composition and texturalnproperties can lead to a significant enhancement in gas storage andnseparation. The differences in the electronic properties of the gasnmolecules and the functionality of the porous networks allow the gasnmolecules to be preferentially adsorbed. In particular, the selectivenuptake of CO2 over CH4 is believed to arise from enhanced CO2-nframework interactions through hydrogen bonding and/or dipolequadrupoleninteractions. Similarly, CH4 adsorbs preferentially overnN2 due to its higher polarizability. Recently, we reported thensynthesis of the benzimidazole-linked polymer (BILP-1) featuringnhigh surface area and nitrogen rich pore walls which exhibits highnCO2 capture.4 Herein we report on the synthesis of a new polymer,nBILP-5 as depicted in Scheme 1 and investigate the performance ofnboth BILPs in CO2/CH4 and N2/CH4 selectivity studies. Our resultsnindicate that these polymers have a promising potential in small gasnseparation applications.