Correlation between Pore Characteristics and High-Performance Carbon Dioxide Capture of Sustainable Porous Carbon Derived from Kraft Lignin and Potassium Carbonate

The development of cost-effective and efficient adsorbents for CO2 capture has gained significant interest, with biomass-derived porous carbon materials emerging as promising candidates due to their outstanding textural properties, tunable porosity, and low production cost. This study introduces for the first time a sustainable fabrication of porous carbon from Kraft lignin using K2CO3 as an environment-friendly activator via a spray drying approach and carbonization process. K2CO3 offers a low-toxic, low-corrosive, and eco-friendly alternative to KOH, making it safer for long-term equipment use and more suitable for large-scale applications. Furthermore, K2CO3 effectively creates a microporous structure for CO2 adsorption while simplifying waste management due to its benign and recyclable carbonate residues. Unlike conventional two-step activation, our approach integrates carbonization and activation into a single step, reducing production time and enhancing efficiency, making it suitable for practical applications. Porous carbon materials obtained through this novel process exhibited a CO2 adsorption capacity of 4.54 mmol/g at 298 K, comparable to those activated with KOH and outperforming many previously reported adsorbents. Additionally, the effects of K2CO3 concentration and carbonization temperature were systematically studied to optimize CO2 adsorption performance. A linear correlation analysis between pore structure parameters and CO2 captures highlighted ultramicropores as key contributors to adsorption efficiency.