Synergistic promotion for CO2 absorption and solvent regeneration by fine waste red mud particles on in amine-based carbon capture: Performance and mechanism

Abstract

Using waste red mud as catalysts for enhancing mass transfer and boosting amine-based solvent regeneration is a promising option for both resources recycling and efficient carbon capture. Here, the effect of fine red mud particles was firstly investigated on carbon dioxide (CO2) absorption and desorption. The Brownian motion and shuttle effect of submicron or micron red mud particles play a positive role in reducing the concentration boundary layer and updating the CO2-species concentration of liquid/gas film, which is beneficial for mass transfer enhancement. Additionally, the composite metal oxides of red mud support abundant acid/base active sites for water dissociation, which can promote the proton transfer and boost carbamate decomposition. Therefore, the average enhancement factor is ∼1.49 and the average absorption rate increases by 22.8 %; while the maximal desorption rate (2.14 mmol/min) increases by 289 % and relative heat duty decreases by 16.3 %, after adding 2.5–5 % red mud particles. The continuous CO2 absorption–desorption experiments verify red mud increases the capture efficiency from 51.6 % (blank test) to 62.4 %. The results offer a favorable technology for reuse of industrial solid waste in the field for low-energy carbon capture.