Highly Efficient CO2 Capture from Wet–Hot Flue Gas by a Robust Trap-and-Flow Crystal

Highly selective CO2 capture from flue gas based on adsorption technology is among the largest challenge on the horizon, due to its high temperature (>333 K), lower partial pressure (0.1–0.2 bar), and competition from water. Due to the designable and tunable pore system, porous coordination polymers (PCPs) have been considered as the most exciting discoveries in porous materials. However, the rational design and function-led preparation of the pore system that permits highly selective CO2 capture from flue gas (CO2/N2/O2/CO/H2O) remains a great challenge. Herein, we report a highly selective CO2 capture from wet–hot (363 K, RH = 40%) flue gas by a robust trap-and-flow crystal (NTU-67). Crystallographic analysis showed that the flow channel provides plausible CO2 traffic, while the confined trap works as an accommodation for captured gas molecules. Further, the hydrophobic pore surface endows the function of the channels that are not influenced by hot moisture, a major obstacle to overcome direct CO2 capture by PCPs. The integral nature of NTU-67, including good stability in SO2, meets the key prerequisites that are usually considered for practical applications. The molecular insight and highly efficient CO2 capture make us believe that different nanospace with their own duties may be extended into ingenious design of more advanced adsorbents for cost-effective and promising for CO2 capture from flue gas.基于吸附技术的高选择性烟道气二氧化碳捕集是当前亟待突破的重大挑战之一，因其面临高温（>333 K）、低分压（0.1~0.2 bar）以及水蒸气竞争的难题。由于孔道系统可设计、可调控，多孔配位聚合物 (porous coordination polymers，PCPs) 被视为多孔材料领域最具突破性的研究进展之一。然而，开发能够从烟道气（CO2/N2/O2/CO/H2O）中高选择性捕集CO2的孔道系统，并实现功能导向的精准设计与制备，仍是一项艰巨挑战。本研究报道了一种稳定的“捕获-流通”型晶体材料（NTU-67），可从湿热（363 K，相对湿度RH=40%）烟道气中实现高选择性CO2捕集。晶体结构分析显示，流通孔道为CO2提供了顺畅的传输通路，而受限的捕获位点则可作为被捕集气体分子的容纳位点。此外，该材料的孔道表面具有疏水性，可使流通孔道不受高温水蒸气的影响——这正是多孔配位聚合物直接捕集CO2所需攻克的核心障碍之一。NTU-67具备优异的整体稳定性（包括良好的SO2耐受性），满足了实际应用所需的关键先决条件。基于本研究获得的分子层面认知与高效CO2捕集性能，我们认为，将各司其职的不同纳米空间融入设计思路，有望开发出更先进的吸附剂，为实现低成本、高性能且极具应用前景的烟道气CO2捕集提供可行路径。