Improved CO₂adsorption onto chemically activated spherical phenol resin

This study reveals the significant improvement of adsorption capacity of carbon dioxide (CO₂) onto spherical phenol resin (PR) activated by potassium hydroxide (KOH), designated KOH6-PR. Experiments were performed using a gravimetric adsorption measurement instrument for the wide range of temperatures 20-70 °C and pressure up to 7 MPa. The measured excess uptakes were found steadily increase up to 5.7 MPa at 25 °C and reached the value of 1.69 g g^-1. After that, a declining trend was observed, which is corrected by the adsorbed gas density and pore volume of the adsorbent. The measured isotherm data were examined using the modified Dubinin-Astakhov (D-A) model, and the Tóth model within a 3.7 % root mean square deviation (RMSD). The maximum CO₂adsorption capacity of microporous KOH6-PR was found 2.36 cm³g^-1using the modified d-A model. The adsorption capacity showed more than 50 % enhancement compared to the widely used Maxsorb III. The average value of heat of adsorption is calculated employing the Clausius-Clapeyron and the modified d-A equations. The cooling performance of an adsorption cycle using the KOH6-PR/CO₂pair is predicted. These analyses are necessary for utilizing CO₂as a refrigerant in adsorption heat pumps and gas storage applications.