Work

Experiments and kinetic modeling of absorption rates of CO2 into unpromoted K2CO3 solutions at low to high solvent loading

Year: 2025

Type: article

Abstract: Absorption by aqueous potassium carbonate is gaining renewed interest as a post-combustion carbon capture technology due to its benign chemistry and low regeneration duty. In this work, we present new experimental data on the absorption rate of CO2 into aqueous K2CO3. We performed absorption experiments on 25 wt% K2CO3 at temperature 313-358 K and solvent loadings up to 70%, using a thermostatted, stirred batch reactor. The apparent enhancement factor was found to decrease with increasing solvent loading due to decrease in hydroxide concentration. A stagnant film model accounting for all reactive species was used to derive the second order rate constant (k2) for the reaction between CO2 and OH-. The k2 was found to decrease with an increase in solvent loading. To explain this behavior we developed an ion-contribution model that relates k2 to the ionic composition of the solvent. The model describes the experiments over the whole range of data with good accuracy. The results of this work are relevent for industrial applications of aqueous K2CO3 where the absorption process is operated at high solvent loading to minimize regeneration duties.

Source: Separation and Purification Technology

DOI: 10.1016/j.seppur.2025.134622

Authors: Nima Mirzaei, Florian Walthert, Efthymios Kantarelis, Matthaus U. Babler

Institution: KTH Royal Institute of Technology

Language: English

Topic: Carbon Dioxide Capture Technologies

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Climate action

Open Access status: hybrid

Estimated APC paid: $4,060