Assessment of the potential use of zeolites synthesized from power plant fly ash to capture CO2 under post-combustion scenario

Two types of zeolites (type X and type A) were synthesized from fly ash of two Brazilian coal based power plants via hydrothermal treatment after ash fusion with NaOH. The synthesized zeolites were characterized by means of XRF, XRD, SEM and gas adsorption (N 2 and CO 2 adsorption/desorption at − 196 and 0 °C, respectively). Pure CO 2 and N 2 adsorption equilibrium isotherms were performed at 50, 70 and 90 °C to measure the CO 2 adsorption capacity and selectivity of CO 2 over N 2 . CO 2 /N 2 binary isotherms (15/85% v/v) were also obtained at the same temperatures. Commercial zeolitic materials used for CO 2 /N 2 separation such as zeolite 13X and zeolite 4A underwent the same characterization and adsorption measurements as benchmarks to evaluate the performance of the synthesized zeolites. The synthesized materials from fly ash are promising low cost adsorbents for CO 2 separation, reaching ca. 83% of the CO 2 adsorption capacity of their commercial counterparts at 0.15 bar and 50 °C.