Anchoring Cu-N active sites on functionalized polyacrylonitrile fibers for highly selective H2S/CO2 separation

As an essential part of clean energy, natural gas is often mixed with varying degrees of H2S and CO2, which poses a serious environmental hazard and reduces the fuel's calorific value. However, technology for selective H2S removal from CO2-containing gas streams is still not fully established. Herein, we synthesized functional polyacrylonitrile fibers with Cu-N coordination structure (PANFEDA-Cu) by an amination-ligand reaction. The results showed that PANFEDA-Cu exhibited a remarkable adsorption capacity (143 mg/g) for H2S at ambient temperature, even in the presence of water vapor, and showed a good separation of H2S/CO2. X-ray absorption spectroscopy results confirmed the Cu-N active sites in as-prepared PANFEDA-Cu and the formed S-Cu-N coordination structures after H2S adsorption. The active Cu-N sites on the fiber surface and the strong interaction between highly reactive Cu atoms and S are the main reasons for the selective removal of H2S. Additionally, a possible mechanism for the selective adsorption/removal of H2S is proposed based on experimental and characterization results. This work will pave the way for the design of highly efficient and low-cost materials for gas separation.