Tetraethylenepentamine-Modified Activated Semicoke for CO₂ Capture from Flue Gas

To separate CO₂ from coal-fired power plant emissions, semicoke, which is cheap and easy to obtain, was further activated to use as the carrier and tetraethylenepentamine (TEPA) was impregnated in the activated semicoke to prepare solid amine sorbents. The effects of activating agents, adsorption temperature, and the presence of water on CO₂ sorption were investigated in a fixed-bed reactor, and the regenerability and adsorption kinetics for prepared sorbents were also studied. The equilibrium adsorption capacity for N₂-activated semicoke (SE-N₂) was 2.70 and 2.14 mmol/g at 20 °C when water was absent and present, respectively, and the equilibrium adsorption capacity for 10 wt % TEPA-modified N₂-activated semicoke (SE-N₂-TEPA10%) was 3.24 and 3.58 mmol/g at 60 °C when water was absent and present, respectively. After 10 cyclic regenerations, the adsorption capacity for SE-N₂-TEPA10% reduced by 7.7% under dry conditions, and SE-N₂-TEPA10% showed good regenerability

Development of Low-Cost Porous Carbons through Alkali Activation of Crop Waste for CO₂ Capture

To achieve the “double carbon” (carbon peak and carbon neutrality) target, low-cost CO2 capture at large CO2 emission points is of great importance, during which the development of low-cost CO2 sorbents will play a key role. Here, we chose peanut shells (P) from crop waste as the raw material and KOH and K2CO3 as activators to prepare porous carbons by a simple one-step activation method. Interestingly, the porous carbon showed a good adsorption capacity of 2.41 mmol/g for 15% CO2 when the mass ratio of K2CO3 to P and the activation time were only 0.5 and 0.5 h, respectively, and the adsorption capacity remained at 98.76% after 10 adsorption–desorption cycle regenerations. The characterization results suggested that the activated peanut shell-based porous carbons were mainly microporous and partly mesoporous, and hydroxyl (O–H), ether (C–O), and pyrrolic nitrogen (N-5) functional groups that promoted CO2 adsorption were formed during activation. In conclusion, KOH- and K2CO3-activated P, especially K2CO3-activated P, showed good CO2 adsorption and regeneration performance. In addition, not only the use of a small amount of the activator but also the raw material of crop waste reduces the sorbent preparation costs and CO2 capture costs

Enhanced CO₂ Adsorption Capacity and Hydrothermal Stability of HKUST‑1 via Introduction of Siliceous Mesocellular Foams (MCFs)

New hierarchical composites containing micropores and mesopores were synthesized by assembling HKUST-1 (Cu₃(BTC)₂) on siliceous mesocellular foams (MCFs). The structure, morphology, and textural properties of as-prepared composites were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and N₂ sorption isotherms, respectively. The results suggest that the coexistence of mesoporous silicas promotes the formation of nanosized MOFs, and the mesostructures of silicas are not destroyed by MOFs. Moreover, the micropore/mesopore volume ratio can be controlled by varying the amounts of MOFs. The CO₂ adsorption capacities were calculated by breakthrough curves, which were tested in a fixed bed. The CO₂ adsorption capacity of the composites reaches 1.40 mmol/g, which is higher than that of bulk HKUST-1. The structure and CO₂ adsorption capacity of the composites after the hydrothermal treatment also have been evaluated. The results show that composite-2 has a larger CO₂ adsorption capacity of 1.68 mmol/g after steam conditioning and that the structure of HKUST-1 in the composites remain stable