Novel CO2 sorbent: Ca(OH)2 with high strength

• The strength of the Ca(OH)2 particle increases with steam partial pressure.
• High hydration temperature results in low Ca(OH)2 particle strength.
• The Ca(OH)2 particle breaking model has been built.
• The strength of CaO from Ca(OH)2 decomposition exhibits a slight decrease.
• We develop an effective approach for CO2 capture by using Ca(OH)2 particles.

Using CaO-based sorbents to circularly absorb CO2 is one of the most interesting technologies for CO2 capture during coal combustion and gasification. The hydration step not only improves the reactivity of the CaO-based sorbent but also produces high-strength Ca(OH)2 particles for long-term CO2 absorption. A novel method of producing Ca(OH)2 with high strength (> 7.0 MPa) under different temperatures and/or steam partial pressures is proposed in this study. The mechanism and the particle breaking model are also discussed. Results indicate that high steam partial pressure and relatively low temperature are suitable conditions for the production of high-strength Ca(OH)2 particles. High steam partial pressure changes the particle structure, such as porosity, and thus enhances the strength of Ca(OH)2 particles. However, high temperature results in low Ca(OH)2 particle strength. This result may be due to the increase in the SBET of Ca(OH)2 particles. A particle breaking model has been developed to explain this. Furthermore, when Ca(OH)2 is decomposed to CaO, the strength of CaO particles becomes lower than that of the original Ca(OH)2. Lastly, a CO2 capture approach that involves the use of Ca(OH)2 particles with high strength is proposed.