High-Performance of SATS-Derived CaO/TiO2–Al2O3 Sorbent for CO2 Capture in Batch Fluidized Bed

Abstract

CaO-based sorbents are widely used to capture CO2 in calcium looping (Ca-L) and chemical looping gasification (CLG) processes due to its relatively low material cost, high availability, fast kinetics and high theoretical CO2 capture capacity. However, a major challenge for Ca-L technology is the rapid decay of CaO during successive carbonation/calcination cycles. To overcome this loss-in-capacity defect, a novel self-assembly template synthesis (SATS) method is proposed to manufacture a hierarchical structure CaO-based sorbent (CaO/TiO2–Al2O3 sorbent). In this study, CaO sorbent (made by calcination method), CaO/Al2O3 sorbent (made by impregnation method), and CaO/TiO2–Al2O3 sorbent (made by SATS method) are manufactured to evaluate their performance on a laboratory scale. The carbonation/calcination cyclic tests of CaO-based sorbents are conducted in batch fluidized bed; in addition, the morphology features and mechanical strength before and after cyclic tests are also researched. After 10 successive cycles, it can be found that CaO/TiO2–Al2O3 sorbent achieves high CO2 capture capacity of 0.78 mol CO2/mol CaO, which is 46 and 36 % higher than those of CaO and CaO/Al2O3, respectively. Meanwhile, CaO/TiO2–Al2O3 sorbent shows high mechanical strength with an appreciable crushing strength of 1.46 N and high sintering resistance with a rich and uniform porous structure. Therefore, it can be concluded that CaO/TiO2–Al2O3 sorbent performs high and durable capture capacity, stable thermal stability, strong mechanical strength and sintering resistance compared with CaO and CaO/Al2O3 sorbents in batch fluidized bed.