Exceptionally High CO2 Capture in an Amorphous Polymer with Ultramicropores Studied by Positron Annihilation
Exceptionally High CO2 Capture in an Amorphous Polymer with Ultramicropores Studied by Positron Annihilation
复制标题
通过正电子湮灭研究超微孔无定形聚合物中极高的二氧化碳捕获率
DOI：
10.1021/acsami.9b07015
复制
发表时间：
2019
影响因子：
9.5
通讯作者：
Chen Zhiquan
中科院分区：
文献类型：
--
作者：
Liu Junjie;Qi Ning;Zhou Bo;Chen Zhiquan
通过改变支链长度，用席夫碱化学方法(SNW)合成了一系列非晶态的三聚氰胺聚合物网络。用气体吸附和正电子湮没等方法分析了其孔结构。正电子寿命测量表明，在SNW材料中存在超微孔和较大的中孔。微孔和中孔的大小基本相同，分别约为0.7 nm和16.5 nm。微孔的相对数量按SNW-1<；SNW-2<；SNW-3的顺序增加，而中孔的数量则相反。氮气吸附/脱附测试还显示了这些材料中的微孔和中孔。然而，它低估了微孔体积。由于SNW材料具有丰富的氮含量和高的微孔隙率，表现出极高的CO2捕集能力，在273K和1bar时，SNW-3的最大值为18.3wt%，其次是SNW-2和SNW-1。这一顺序与正电子湮没法测得的微孔体积大小完全相同，说明微孔在CO2吸收中起着至关重要的作用。结果表明，正电子能提供更准确的微孔结构信息，从而为复杂多孔材料的吸附容量提供准确的预测。
A series of amorphous melamine-based polymer networks synthesized by Schiff base chemistry (SNW) were successfully prepared by varying the strut length. The pore structure was analyzed by gas adsorption and positron annihilation methods. Positron lifetime measurements indicate the existence of ultramicropores and also larger mesopores in the SNW materials. The sizes of micropores and mesopores are almost the same in these samples, which are about 0.7 and 16.5 nm, respectively. The relative number of micropores increases in the order of SNW-1 < SNW-2 < SNW-3, while the number of mesopores increases in the reverse order. N2adsorption/desorption measurements also reveal micropores and mesopores in these materials. However, it gives an underestimation of the micropore volume. Benefiting from the abundant nitrogen content and high microporosity, the SNW materials exhibit exceptionally high CO2capture ability, which reaches a maximum value of 18.3 wt % in SNW-3 at 273 K and 1 bar, followed by SNW-2 and SNW-1. This order is exactly the same as the order of micropore volume revealed by positron annihilation measurement, suggesting that micropores play a crucial role in the CO2uptake. Our results show that positron can provide more precise information about the structure of micropores and thus can offer an accurate prediction for the adsorption capacity of complex porous materials.