Recent advances in capture of carbon dioxide using alkali-metal-based oxides

Carbon dioxide (CO2) is a major greenhouse gas and makes a significant contribution to global warming and climate change. Thus CO2 capture and storage (CCS) have attracted worldwide interest from both fundamental and practical research communities. Alkali-metal-based oxides such as alkali-metal oxides, binary oxides, and hydrotalcite-like compounds are promising adsorbents for CO2 capture because of their relatively high adsorption capacity, low cost, and wide availability. They can also be applied to the adsorption-enhanced reactions involving CO2. The microstructures (e.g., surface area, porosity, particle size, and dispersion) of these oxides determine the CO2 adsorption capacity and multicycle stability. This perspective critically assesses and gives an overview of recent developments in the synthesized method, adsorption mechanism, operational conditions, stability, and regenerability of a variety of oxides. Both pros and cons of these oxides are also discussed. Insights are provided into several effective procedures regarding microstructural control of alkali-metal-based oxides, including preparation optimization, modification, stream hydration, etc.