Peng Hu,Mingyuan Jiang,Jialang Hu,Long Li,Gui Shi,Lvming Jin,Yonggang Zhang,Chao Xiong,Hongbing Ji
The efficient separation and purification of natural gas (NG) represents a pivotal industrial procedure. Herein, we rationally designed a hierarchical-discrete MOF (denoted as 1a ) with molecular nanotraps that enable highly efficient C 3 H 8 capture and kinetic separation from light alkane mixtures (CH 4 /C 2 H 6 /C 3 H 8 ). N 2 adsorption analysis and pore visualization reveal hierarchically discrete pore geometries with ultra-submicroporous dimensions of 5.0 × 4.9 Å 2 and 8.3 × 8.2 Å 2 , effectively optimizing the formation of C 3 H 8 -selective molecular nanotraps while improving gas storage and diffusion kinetics through interconnected ultra-submicroporous channels. Significantly, 1a demonstrates exceptional separation performance, with IAST selectivity of equimolar C 3 H 8 /CH 4 and C 2 H 6 /CH 4 for 1a is 575.6 and 34.8 at zero coverage and 298 K, surpassing many well-known MOFs. Dynamic breakthrough experiments confirm the effective separation of ternary CH 4 /C 2 H 6 /C 3 H 8 mixtures and combined density functional theory (DFT) calculations, transient two-dimensional electron-density maps (2D-EDM),etc., reveal the molecular-level host–guest binding mechanisms. This work highlights the importance of multiscale pore cooperation for synergistically enhancing gas storage capacity and diffusion kinetics.
Herein, a variety of 2,6-diaminopyridine (DAP) derived nitrogen-doped hierarchically porous carbon (DAP-NHPC-T) prepared from carbonization-induced structure transformation of DAP-Zn-SiO 2 -P123 nanocomposites are reported, which are facilely prepared from solvent-free co-assembly of block copolymer templates P123 with pyridine-rich monomer of DAP, Zn(NO 3 ) 2 and tetramethoxysilane. In the pyrolysis process, P123 and SiO 2 templates promote the formation of mesoporous and supermicroporous structures in the DAP-NHPC-T, while high-temperature volatilization of Zn contributed to generation of micropores. The DAP-NHPC-T possess large BET surface areas (≈956–1126 m 2 g −1 ), hierarchical porosity with micro-supermicro-mesoporous feature and high nitrogen contents (≈10.44–5.99 at%) with tunable density of pyridine-based nitrogen sites (≈5.99–3.32 at%), exhibiting good accessibility and reinforced interaction with SO 2 . Consequently, the DAP-NHPC-T show high SO 2 capacity (14.7 mmol g −1 , 25 °C and 1.0 bar) and SO 2 /CO 2 /N 2 IAST selectivities, extraordinary dynamic breakthrough separation efficiency and cycling stability, far beyond any other reported nitrogen-doped metal-free carbon. As verified by in situ spectroscopy and theoretical calculations, the pyridine-based nitrogen sites of the DAP-NHPC-T boost SO 2 adsorption via the unique charge transfer, the adsorption mechanism and reaction model have been finally clarified.
危险品化学品经营许可证（带存储）