Biomass-Based N-Rich Porous Carbon Materials for CO₂ Capture and in-situ Conversion

Capturing CO₂ and subsequently converting into valuable chemicals has attracted extensive attention. Herein, a series of biomass-based N-rich porous carbon materials with high specific surface area and pore volume were prepared using biomass waste soybean dregs as precursors. The nitrogen content was up to 4 % with different forms in the carbon skeleton such as pyridine-N, pyrrole-N. The synergistic effect of ultra-micropore (pore size <0.7 nm) and N-containing groups endowed the materials with a high CO₂ adsorption capacity, reaching 6.3 and 3.6 mmol g^-1 at 0 and 25 °C under atmospheric pressure, respectively. In addition, the sufficient interaction between N-containing groups and CO₂ was demonstrated by solid-state nuclear magnetic resonance spectroscopy, and the captured CO₂ was possibly activated in the form of carbamate, which is conducive to subsequent conversion. Therefore, the supported catalyst with the as-synthetic porous carbon material as the carrier and Zn^II as catalytic sites was prepared and successfully applied for carboxylative cyclization of propargylic amine with CO₂ to afford the 3-benzyl-5-methyleneoxazolidin-2-one. The results showed that CO₂ capture and in-situ conversion work effectively to produce highly value-added chemicals. In this process, the captured CO₂ could be activated and fixed into chemicals in mild conditions. More importantly, the energy consumption in CO₂ desorption and adsorbent regeneration could be avoided. The valorization of both solid waste and CO₂ to valuable chemicals provides an elegant strategy of killing three birds with one stone.