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

• Published in: Journal of CO2 utilization 2023-01, Vol.67, p.102296, Article 102296
• Main Authors: de Oliveira, Leonardo H., Pereira, Marcus V., Meneguin, Joziane G., de Barros, Maria Angélica S.D., do Nascimento, Jailton F., Arroyo, Pedro A.
• Format: Article
• Language: English
• Subjects: Blowdown step; Carbon dioxide; Cyclic adsorption; LTA; Working capacity
• ISSN: 2212-9820; 2212-9839
• DOI: 10.1016/j.jcou.2022.102296

This work aimed to determine the influence of different regeneration conditions on CO2 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 CO2/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. CO2 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 CO2/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 CO2 separation when pressure and temperature are changed in blowdown/regeneration step. [Display omitted] •CO2/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 CO2/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.