Saleh Muhammad, Lee Han Myoung, Kemp K Christian, Kim Kwang S
Department of Chemistry, Pohang University of Science and Technology , Pohang 790-784, Korea.
ACS Appl Mater Interfaces. 2014 May 28;6(10):7325-33. doi: 10.1021/am500728q. Epub 2014 May 13.
The largest obstacles for landfill/flue gas separation using microporous materials are small adsorption values and low selectivity ratios. This study demonstrates that these adsorption and selectivity challenges can be overcome by utilizing a series of hyper-cross-linked heterocyclic polymer networks. These microporous organic polymers (MOPs) were synthesized in a single step by inexpensive Friedel-Crafts-catalyzed reactions using dimethoxymethane as an external linker. The amorphous networks show moderate Brunauer-Emmett-Teller surface areas up to 1022 m(2) g(-1), a narrow pore size distribution in the range from 6 to 8 Å, and high physicochemical stability. Owing to the presence of the heteroatomic pore surfaces in the networks, they exhibit maximum storage capacities for CO2 of 11.4 wt % at 273 K and 1 atm. Additionally, remarkable selectivity ratios for CO2 adsorption over N2 (100) and CH4 (15) at 273 K were obtained. More importantly, as compared with any other porous materials, much higher selectivity for CO2/N2 (80) and CO2/CH4 (15) was observed at 298 K, showing that these selectivity ratios remain high at elevated temperature. The very high CO2/N2 selectivity values are ascribed to the binding affinity of abundantly available electron-rich basic heteroatoms, high CO2 isoteric heats of adsorption (49-38 kJ mol(-1)), and the predominantly microporous nature of the MOPs. Binding energies calculated using the high level of ab initio theory showed that the selectivity is indeed attributed to the heteroatom-CO2 interactions. By employing an easy and economical synthesis procedure these MOPs with high thermochemical stability are believed to be a promising candidate for selective CO2 capture.
使用微孔材料进行垃圾填埋气/烟道气分离的最大障碍是吸附值小和选择性比率低。本研究表明，利用一系列超交联杂环聚合物网络可以克服这些吸附和选择性挑战。这些微孔有机聚合物（MOPs）通过使用二甲氧基甲烷作为外部连接体的廉价傅-克催化反应一步合成。这些无定形网络具有高达1022 m² g⁻¹ 的适度布鲁诺尔-埃米特-泰勒表面积、6至8 Å范围内的窄孔径分布以及高物理化学稳定性。由于网络中存在杂原子孔表面，它们在273 K和1 atm下对CO₂的最大存储容量为11.4 wt%。此外，在273 K时获得了对CO₂吸附相对于N₂（100）和CH₄（15）的显著选择性比率。更重要的是，与任何其他多孔材料相比，在298 K时观察到对CO₂/N₂（80）和CO₂/CH₄（15）的选择性更高，表明这些选择性比率在升高温度时仍然很高。非常高的CO₂/N₂选择性值归因于大量存在的富电子碱性杂原子的结合亲和力、高CO₂等量吸附热（49 - 38 kJ mol⁻¹）以及MOPs主要的微孔性质。使用高水平从头算理论计算的结合能表明，选择性确实归因于杂原子与CO₂的相互作用。通过采用简单且经济的合成方法，这些具有高热化学稳定性的MOPs被认为是选择性捕获CO₂的有前途的候选材料。
