CaMn2O4 modified CaO composites with paper fiber structure for efficient CO2 capture and energy storage of coal fired power plants

Calcium looping (CaL) is a promising technology for CO 2 capture from coal-fired power plants, but it suffers from rapid activity loss of calcium-based materials. The hydration-CO 2 capture-calcination (CaHCL) process can reactivate the pore structure of calcium-based materials, yet the intrinsic reactivity of conventional CaO materials remains insufficient, leading to low hydration and carbonation conversions and high system energy consumption. Herein, a CaMn 2 O 4 -modified CaO composite with a paper fiber structure was synthesized via a sacrificial template method. Fixed-bed experiments showed that the optimized CaO composite, designated Mn 0.75 CaAP, maintained a hydration conversion above 0.92 and an effective CO 2 capture conversion of 0.77 over 20 CaHCL cycles. These values represent substantial improvements over unmodified CaO and over materials modified by either templating or Mn doping alone. Characterization results revealed that the hollow tubular framework not only preserves a stable mesoporous network by accommodating the volume expansion during hydration, but also exposed the active sites and promoted the formation of CaMn 2 O 4 . The CaMn 2 O 4 spinel introduced abundant oxygen vacancies, which accelerated the chemisorption of H 2 O and CO 2 . Process simulation showed that at a Ca/C ratio of 1.25, the system achieved over 90% CO 2 capture efficiency with an energy consumption of only 857.84 MJ/(ton·CO 2 ), which is 38.1% and 23.5% lower than those of the CaHCL with conventional CaO and the CaL process, respectively. These results demonstrate promising laboratory-scale performance of Mn 0.75 CaAP and favorable simulated process behavior, supporting further investigation of Mn 0.75 CaAP for potential application in CaHCL-based CO 2 capture and thermochemical energy storage.