Bioenergy carbon capture and storage (BECCS) is expected to play a pivotal role in achieving substantial reductions in greenhouse gas emissions in line with international climate agreements. Conventional CO₂ separation from flue gases relies on chemical absorption into alkaline scrubbing fluids. The technology is well-understood but suffers from several technical limitations, of which the most notable is the high energy penalty associated with the high water content. Although a range of phase separating solvents has emerged as an alternative approach for improving energy efficiency in CO₂ capture systems, this thesis focuses on new dispersion-based formulations, which remain underexplored despite their potential to anchor amine species and thereby reduce emissions and toxicity.

This thesis investigates dispersion-based scrubbing fluids for energy efficient CO₂ capture, based on the hypothesis that CO₂-triggered phase separation can significantly reduce regeneration energy. In parallel, it also examines biocatalysis by carbonic anhydrases (CAs) with an emphasis on adsorption-induced thermal stabilization as a strategy to enhance enzyme durability under harsh industrial conditions.

Concentrated dispersions of aminated SBA-15 silica and aminated nanoparticles of organosilica were synthesized and evaluated for their CO₂ capture performance. A central aspect of the performance was the CO₂-triggered phase change, which was studied by time-resolved optical transmission, and CO₂ absorption rates were measured by CO₂ partial pressure decay in a stirred-cell apparatus. In addition, CAs from thermophilic and mesophilic organisms were immobilized on aminated SBA-15 and ZIF-90. The immobilized CAs were incubated at elevated temperatures, and the remaining catalytic activity was evaluated via esterase assay and CO₂ hydration rates.

CO₂-triggered phase separation occurred in the dispersions of aminated SBA-15 and monoaminated nanoparticles (M-NP), but not in the di- (D-NP) and triaminated (T-NP) nanoparticles. CO₂ absorption rates of the aminated nanoparticles were comparable to those of industrial benchmarking scrubbing fluids such as monoethanolamine (MEA) and 2-amino-2-methyl-1-propanol (AMP). The rate of CO₂ absorption into the aminated SBA-15 dispersions was limited due to slow mass transfer. Phase separation significantly improved the energy balances, with an approximately 50% reduction in regeneration energy according to our calculations, demonstrating the potential to reduce regeneration energy in industrial applications. CAs immobilized on aminated SBA-15 and ZIF-90 exhibited enhanced thermal stability at elevated temperatures. The structural stability of the solid support appears to be the bottleneck in achieving greater thermal stability.

This thesis demonstrates the potential for enhanced performance and energy benefits of dispersion-based scrubbing fluids for CO₂ capture, as an alternative to conventional molecular solvents. It also highlights their suitability for integration of CA-based biocatalysis by improving CA stability via adsorption.