Preparation of microporous carbonaceous CO2 adsorbents by activating bamboo shoot shells with different chlorides: Experimental and theoretical calculations

In this paper, a series of microporous carbonaceous adsorbents were prepared using bamboo shoot shells as carbon precursors and four different chlorides (calcium chloride, potassium chloride, iron chloride and zinc chloride) as activators. The results show that the pore structure and specific surface area of the adsorbent jointly affect the adsorption capacity of CO2. The porous carbon prepared with calcium chloride and potassium chloride as the activator has the highest micropore content, reaching more than 93 %. The solid adsorbent BSSC-CaCl2-700 with calcium chloride as the activator exhibited the highest CO2 adsorption capacity of 70.45 cm3/g and 53.62 cm3/g at 273 K and 298 K under 1 bar, respectively. It is a promising adsorbent for CO2 capture from flue gas. Based on the experimental study, a model of porous carbon prepared by different activators was developed. Combined with the mechanism of CO2 adsorption in porous materials, the binding adsorption energy and self-diffusion coefficient of porous carbon prepared by the different chlorides as activators were calculated by DFT method. The results show that the adsorption energy of porous carbon with calcium chloride as an activator is − 8.1 KJ/mol, and the self-diffusion coefficients are 8 × 10−7 and 1.3 × 10−7 at 273 K and 298 K, respectively. The fitted R2 was both greater than 0.95. Therefore, the selected model can better illustrate that chloride has a stronger effect on the preparation of microporous biomass carbon, which provides an idea for subsequent experiments and theoretical research.