Enhancement of attrition resistance and cyclic CO2 capture of calcium-based sorbent pellets

Abstract

Calcination/carbonation of calcium-based sorbent is considered one of the most promising technologies to capture CO2. The attrition resistance and CO2 uptake of Ca-based sorbent were of great concern. Efforts were made to enhance the attrition resistance of sorbents primarily by making sorbent pellets with aluminate cements and maintain high CO2 capture capacity of sorbents by adding pore forming agents. Batch experiments were conducted in a fluidized bed to investigate the effect of parameters on sorbent attrition. CO2 capture performance of the pellets was also examined in a calcination/carbonation reactor system. The pore structure characteristics (BET, BJH) were measured as a supplement to the attrition and reaction studies. Results showed that the mechanical property of the pellets with 10wt.% aluminate cement was greatly enhanced. While, CO2 capture capacity of the pellets made with 10wt.% aluminate cement and 5–10wt.% pores forming agent was greatly increased and displayed much slower decay during multiple cycles compared with the original limestone. This was attributed to the large number of mesopores caused by the use of chemical agents and the exposure of inner core of CaO sorbents due to the attrition, which are in favor of CO2 capture. The pore structure showed that the BET surface area and BJH pore volume were expanded by adding pore forming agents, which benefits CO2 uptake of the sorbents during the cycling.