Modifying absorption process configurations to improve their performance for Post-Combustion CO₂ capture – What have we learned and what is still Missing?

Mitigation of climate change by reducing the anthropogenic CO₂ emissions has recently gained huge momentum. A prime pathway to achieve it in the short-medium term lies within capturing CO₂ from industries’ flue gases. Post-combustion CO₂ capture (PCC) is the most mature methodology for large-scale CO₂ capture and closest to market. However, the conventional chemical absorption-based PCC process implies high regeneration energy requirements, constituting the majority of the energy load when adding PCC to the plant from which the CO₂ is going to be captured. As such, reducing the overall parasitic load of the conventional process is of interest. Changing the solvent or improving the process flowsheet are two main methodologies to achieve higher energetic efficiency and lower exergy losses. As there are several reviews dealing with novel solvents, this review critically evaluates the progress in improving the conventional PCC process through modifications of process configurations and shadowed by solvent replacements as drop-in solutions. The process configurations were grouped into absorption and stripping enhancement categories. A comparative analysis was conducted between the different available schemes in the literature and interactions between solvents and process configurations were showcased, highlighting the advantages and shortcomings of some of them. The review reveals the need for standardized framework and optimization algorithms using exergo-economic performance indicators for integrated solvent and process synthesis.