Enhanced Performance of Chemical Looping Combustion of CO with CaSO4-CaO Oxygen Carrier

CaSO4 is an interesting alternative oxygen carrier for chemical looping combustion (CLC). Utilization of a CaSO4 oxygen carrier suffers deactivation caused by sulfur loss. To prevent sulfur loss, a small amount of CaO particles were mixed with the CaSO4 oxygen carrier. The predominant regions of CaSO4, CaS, and CaO have been obtained with consideration of SO2 and COS emissions. The predominant region of CaO is increasing with the temperature and CO2 partial pressures. Isothermal as well as nonisothermal kinetics of CaSO4-based oxygen carrier reduction, and reduction/oxidation cycle tests, have been carried out. The effects of reaction temperature, CO concentration, and molar ratio of CaO to CaSO4 and cycle number on sulfur emission and CO2 generation efficiency are taken into account. XRD, XRF, and gas analyses were performed to investigate the variations of solid phase change, elements composition in solid residual, and sulfur release with reaction time. The results show that the use of fresh CaO additiv...