Effects of CaCl2 on cyclic carbonation-calcination kinetics of CaO-based composite for potential application to solar thermochemical energy storage. (2nd February 2021)

• Record Type: Journal Article
• Authors: Choi, Dasol; Shin, Jiwoo; Park, Youngjune
• Is Part Of: Chemical engineering science. Volume 230(2021)
• Publication Date: 2021-02-02
• Subjects: Calcium looping -- Calcium carbonate -- Passivation -- Mass transfer -- Sintering; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2020.116207
• Languages: English
• ISSNs: 0009-2509

Abstract

Highlights: Effects of CaCl2 on the CaO-based sorbents are investigated. Added CaCl2 provides diffusion of CO2 through surface layer passivated by CaCO3 . Added MgO mitigates surface area reduction of composite by CaCl2 . The CaCl2 and MgO additives improve reaction rate and conversion performances. The carbonation-calcination mechanism of provided composite is proposed. Abstract: The calcium looping (CaL) process is a promising thermochemical energy storage option for concentrated solar power systems due to its great advantages of high energy density and low material cost. However, CaO-based sorbents often suffer from continuous degradation in their reversibility due to the formation of a passivation layer and evolution of a sintering effect. In this work, we focused on the effects of CaCl2 as an additive to CaO sorbents with the aim to enhance reversibility by addressing the mass-transfer issue. A variety of CaO-based sorbents with CaCl2 were synthesized, characterized, and examined their reaction patterns during cyclic carbonation-calcination. The experimental results show that the addition of CaCl2 enhances the rate of the carbonation reaction, based on enhanced reactant diffusion. The CaCl2 causes reduction of surface area; however, the addition of MgO effectively delays sintering. Therefore, CaO-based sorbents with CaCl2 and MgO achieved high reversibility with enhanced durability.