Development and performance of binder-supported CaSO4 oxygen carriers for chemical looping combustion

Chemical-looping combustion (CLC) has been recognized as an energy-efficient method for CO 2 capture. For calcium sulfate (CaSO 4 ) oxygen carrier, the rapid fall in the mechanical strength and reactivity limits its application in CLC. In this study, Taguchi robust design method with L 9 orthogonal array was implemented to optimize extrusion condition for the preparation of binder-supported CaSO 4 oxygen carriers. The orthogonal experiment results showed the addition of SB powder enhanced both mechanical strength and conversion of CaSO 4 , and the optimal extrusion condition was 30   g CaSO 4 , 12   g SB powder, 2.5   mL acetic acid, and 15   mL water. The favorable oxygen carriers were comprehensively studied in a fixed bed reactor. The results of reduction test showed the mass-based reaction rates of the binder-supported CaSO 4 were significantly increased, because the fresh samples had the higher surface area which was evidenced by pore structure analysis. Moreover, the favorable performance of binder-supported CaSO 4 was explained by formation of CaAl 2 O 4 which had excellent thermal stability and provided a stable nanosized framework between the crystal grains observed by field emission scanning electron microscope (FESEM).