Hierarchically N-doped porous carbon synthesized from 3D cellulose alcogel decorated by in-situ growth of ZIF-8 for high performance CO2 capture

The physical properties and chemical compositions of porous carbons are crucial factors in determining their effectiveness in adsorbing CO 2 . Cellulose-based porous carbon has emerged as an outstanding candidate adsorbent for CO 2 capture. The research involved the creation of hierarchically nitrogen-doped porous carbon (HNC) using a 3D cellulose alcogel (CA) as substrate, which was prepared through a thermal introduced phase separation (TIPS) method combined with hydrolysis treatment. The plentiful functional groups of CA offered abundant growth sites for the introduction of ZIF-8 crystals. CA/ZIF-8 composite alcogel (CZA) with greater surface area and superior thermal stability compared to CA was successfully fabricated and used as precursor for the production of HNC. The important effects of microporosity and surface chemistry of HNC samples on CO 2 capture were discussed in-depth. HNC-350–850 displayed a hierarchically porous structure with a large number of micropores and abundant N/O/Zn-doped functional groups, exhibiting high CO 2 uptakes at 1 bar (3.56 mmol/g at 25 °C), good IAST CO 2 /N 2 (15/85, V/V) selectivity of 16.31 at 25 °C, and outstanding regenerability with ∼100 % CO 2 adsorption capacity retained after ten cycles. In the two-component CO 2 /N 2 (15/85, V/V) competitive adsorption process, the maximum breakthrough periods for CO 2 (433.1 s) is significantly longer than that of N 2 (3.8 s). The CO 2 breakthrough adsorption capacity reached 1.79 mmol/g at 25 °C and 1 bar with the separation coefficient of 45.8 for CO 2 over N 2 . These results confirmed that HNC, in addition to having excellent CO 2 /N 2 selectivity, demonstrated good feasibility for practical use. The green and practicable synthetic route described in this study is not only expected to offer novel adsorbents for high performance CO 2 capture, but also provide a new theoretical foundation for the development of cellulose-based porous materials.