Negative Charge Confined Amine Carriers within the Nanowire Network for Stable and Efficient Membrane Carbon Capture

Membrane-based carbon dioxide (CO₂) capture has attracted great research interest owing to its potential for higher separation efficiency and lower energy consumption. However, it is still a challenging task to capture CO₂ with membrane from flue gas, especially under moderate-temperature and high-humidity conditions. In this work, a stable CO₂-selective membrane that can operate at temperatures up to 90 °C and under high humidity is reported. The positively charged amine carriers for CO₂ are confined within the negatively charged polymer modified carbon nanotube (CNT) network. In this structure, interconnected CNTs act as the framework for the selective layer and provide numerous nanochannels for gas transport. The negatively charged polymer ensures the carrier stability and further regulates the size of nanochannels in the CNT network. By virtue of carrier-facilitated transport, high CO₂ permeance (up to 3300 gas permeation units) and high CO₂/N₂ selectivity (400) are achieved under simulated flue gas conditions. Moreover, theoretical calculations verify that the stable separation performance is due to the strong electrostatic interaction between the amine carriers and polymer matrix. The high performance and good stability indicate the great potential of this novel membrane structure for practical application in CO₂ capture.