Influence of regeneration conditions on cyclic CO2 adsorption on NaA zeolite at high pressures.

This work aimed to determine the influence of different regeneration conditions on CO 2 adsorption on NaA zeolite at high pressures through cyclic processes. To reach this goal, NaA characterization, high-pressure adsorption isotherms, heat of adsorption and working capacities for CO 2 /NaA system were performed. NaA zeolite characterization showed a high crystalline and stable microporous structure with 0.43 nm pore diameter and 247 m² g^-1 specific area. CO 2 adsorption isotherms are strongly favorable, showing adsorption uptakes equal to 4.73, 4.54 and 4.44 mol kg^-1 (c.a. 20 wt%) at 40 bar and 20, 30 and 40 °C, respectively. Jensen-Seaton model fits experimental data and was used to determine CO 2 /NaA heats of adsorption from 10 to 40 kJ mol^-1, which are characteristic of physisorption process. This was corroborated by constant working capacity for all regeneration processes, reaching 1.44, 3.27, and 4.27 mol kg^-1 for REG-1 (1 bar, 30 °C), REG-2 (vacuum, 30 °C) and REG-3 (vacuum, 150 °C) regeneration processes, respectively. The working capacity simulation showed a strong influence of pressure and practically insensitive to adsorption temperature from 20° to 40°C. Therefore, NaA zeolite is a regenerative material showing a high potential for utilization in high pressure cyclic adsorption processes, such as fixed and fluidized beds, for CO 2 separation when pressure and temperature are changed in blowdown/regeneration step. [Display omitted] • CO 2 /NaA working capacities from 1.44 up to 4.27 mol kg^-1 were found for different regeneration conditions studied system. • Working capacity curves found can be considered as a kernel for regeneration cyclic processes. • Jensen-Seaton model fits CO 2 /NaA adsorption data better than Langmuir, Sips, Tóth and Dubinin-Astakhov models. • Heat of adsorption reaches 40 kJ mol^-1 maximum value probably due to adsorbate-adsorbate interaction below 5.5 bar. [ABSTRACT FROM AUTHOR]