SO2 removal performances of Al- and Mg-modified carbide slags from CO2 capture cycles at calcium looping conditions

摘要

In this work, the SO2 removal performances of the aluminum- and the magnesium-modified carbide slags fabricated by the combustion synthesis from CO2 capture cycles at the calcium looping conditions were investigated in a thermogravimetric analyzer and a dual fixed-bed reactor. The effects of sulfation temperature, number of CO2 capture cycles and calcination condition on the SO2 removal performances of Al- and Mg-modified carbide slags experienced the multiple CO2 capture cycles were studied. The sulfation temperature in the range of 800-950 degrees C shows a little effect on SO2 removal capacities of Al- and Mg-modified carbide slags experienced the multiple CO2 capture cycles. As the number of CO2 capture cycles increases, the sulfation conversions of the original and modified carbide slags decrease rapidly. However, Al- and Mg-modified carbide slags possess obviously higher SO2 removal capacity and cyclic stability than original carbide slag due to the good supports Ca3Al2O6 and MgO, respectively. And the larger surface areas and volumes of pores in 5-20 nm in diameter of Al- and Mg-modified carbide slags promote the higher SO2 removal capacity than original carbide slag. The modified carbide slag shows higher sintering resistance in high concentration of steam calcination condition during the CO2 capture cycles, compared with high concentration of CO2 calcination condition. Therefore, Al- and Mg-modified carbide slags from CO2 capture cycles based on calcium looping calcined under high steam concentration achieve SO2 removal capacities.