Shedding Light on Solid Sorbents: Evaluation of Supported Potassium Carbonate Particle Size and Its Effect on CO2 Capture from Air

Nazila Masoud; Victorien Clement; Tomas van Haasterecht; Marlene Führer; Jan P Hofmann; Johannes Hendrik Bitter

doi:10.1021/acs.iecr.2c01508

Shedding Light on Solid Sorbents: Evaluation of Supported Potassium Carbonate Particle Size and Its Effect on CO₂ Capture from Air

Ind Eng Chem Res. 2022 Sep 28;61(38):14211-14221. doi: 10.1021/acs.iecr.2c01508. Epub 2022 Sep 10.

Authors

Nazila Masoud¹, Victorien Clement¹, Tomas van Haasterecht¹, Marlene Führer¹, Jan P Hofmann^{2

3}, Johannes Hendrik Bitter¹

Affiliations

¹ Biobased Chemistry and Technology, Wageningen University, P.O. Box 17, 6700AA Wageningen, The Netherlands.
² Laboratory for Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
³ Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, 64287 Darmstadt, Germany.

Abstract

Solid sorbents are essential for developing technologies that directly capture CO₂ from air. In solid sorbents, metal oxides and/or alkali metal carbonates such as potassium carbonate (K₂CO₃) are promising active components owing to their high thermal stability, low cost, and ability to chemisorb the CO₂ present at low concentrations in air. However, this chemisorption process is likely limited by internal diffusion of CO₂ into the bulk of K₂CO₃. Therefore, the size of the K₂CO₃ particles is expected to be an important factor in determining the kinetics of the sorption process during CO₂ capture. To date, the effects of particle size on supported K₂CO₃ sorbents are unknown mainly because particle sizes cannot be unambiguously determined. Here, we show that by using a series of techniques, the size of supported K₂CO₃ particles can be established. We prepared size-tuned carbon-supported K₂CO₃ particles by tuning the K₂CO₃ loading. We further used melting point depression of K₂CO₃ particles to collectively estimate the average K₂CO₃ particle sizes. Using these obtained average particle sizes, we show that the particle size critically affects the efficiency of the sorbent in CO₂ capture from air and directly affects the kinetics of CO₂ sorption as well as the energy input needed for the desorption step. By evaluating the mechanisms involved in the diffusion of CO₂ and H₂O into K₂CO₃ particles, we relate the microscopic characteristics of sorbents to their macroscopic performance, which is of interest for industrial-scale CO₂ capture from air.