Hybrid – Slurry/Nanofluid systems as alternative to conventional chemical absorption for carbon dioxide capture: A review

The mitigation of carbon dioxide emissions using hybrid-slurry systems evolved over recent years as an alternative for conventional processes for CO₂ capture. The hybrid systems capture CO₂ by both of adsorption and absorption processes. Generally, this review discusses the concept, provides illustrations, preparation techniques, transport mechanisms and separation performance for different slurry systems found in the literature. Various slurry/nanofluid systems were screened to identify their gas separation performance based on gas uptake (amount and rate), sorption and desorption enthalpy and kinetics as compared to chemical absorption processes. The hybrid systems are categorized as aqueous, amine, alcohol, ionic liquid, Nanoparticle Organic Hybrid Materials (NOHMs), and enzymatic based. Various solid adsorbents are suspended in these solvents include carbons, zeolites, metal oxides, metal organic frameworks (MOFs) and Zeolite Imidazolate Frameworks (ZIFs). Overall, the slurry systems provide some strengths represented in lower regeneration energy and enhanced mass transfer by different mechanisms. On the other hand, the application of hybrid-slurry systems is challenged by different limitations such as material cost, pumping difficulty, wearing and erosion, phase stability, and solvent degradation. These challenges require proper addressing and tackling to move the hybrids towards large scale applications.