Triple Templates Directed Synthesis of Nitrogen‐Doped Hierarchically Porous Carbons from Pyridine Rich Monomer as Efficient and Reversible SO2 Adsorbents

Abstract

AbstractHerein, 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‐SiO2‐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(NO3)2 and tetramethoxysilane. In the pyrolysis process, P123 and SiO2 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 m2 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 SO2. Consequently, the DAP‐NHPC‐T show high SO2 capacity (14.7 mmol g−1, 25 °C and 1.0 bar) and SO2/CO2/N2 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 SO2 adsorption via the unique charge transfer, the adsorption mechanism and reaction model have been finally clarified.