Attrition resistance of calcium oxide–copper oxide–cement sorbents for post-combustion carbon dioxide capture

Abstract

Integrating calcium looping (CaL) and chemical looping combustion (CLC) is potentially more energy efficient than existing technology for post-combustion CO2 capture. Mixtures of CaO, CuO and cement (cem) are promising sorbents but attrition losses due to abrasion and fragmentation could incur an unacceptable economic penalty. We assessed the attrition resistance of many fluidized bed powders with a jet mill at orifice velocities from 180ms-1 to sonic velocity. The attrition resistance of calcium oxide–copper oxide–cement sorbents and crushed cadomin limestone are poorer than vanadyl pyrophosphate (VPP) and fluid catalytic cracking catalyst (FCC). The attrition rates of VPP and FCC at an orifice gas velocity of 180ms−1 were 5mgh−1 and 7mgh−1, respectively; it was 10mgh−1 for powders with a mass fraction of 50% CuO 40% CaO and 10% cement. The (CaO)90cem fragments to smaller sister particles and produces fines but the fines collected overhead in the thimble filter decreases with temperature. The (CaO)40(CuO)50cem10 attrition resistance improved above 500°C and the d50 of the pellets remaining in the jet cup increased from 330μm to 422μm: the Cu agglomerated the pellets. Attrition rates increased with the square of the orifice diameter, the cube of the gas velocity and to the power 0.4 with gas molecular weight.