Kinetics of CO2 adsorption by temperature swing adsorption on KOH-impregnated activated carbon in powder and pellets

Resumo

In this work, a preliminary study was conducted on the CO₂ adsorption performance of KOH-activated carbons in pellet and powder form. The morphologies of the materials were evaluated by scanning electron microscopy. The textural properties were obtained by nitrogen physisorption in a pressure range of P/P₀ = 10^-6 – 1.0. Temperature-programmed adsorption studies were performed by thermogravimetry of the adsorbents. The CO₂ adsorption capacity obtained at 30ºC was 85.88 mg g^-1 for biochar from yellow mombin seed activated with KOH in a mass ratio of 1:1 and 57.77 mg g^-1 for the pellet, hence the powder form resulted in a higher adsorption capacity, which may be related to the textural properties of the adsorbents. The adsorption kinetics were investigated and showed more precise correlations with the pseudo-first-order model for the activated carbon, both in powder and pellet forms (r² = 0.9578 and 0.9510, respectively). Cyclic adsorption studies were performed, and CO₂ capture remained stable after 5 adsorption cycles.