Investigation into compound CaSO₄ oxygen carrier for chemical-looping combustion

In this study chemical-looping combustion of methane with compound CaSO₄ oxygen carrier prepared by impregnation method was investigated in a fixed bed reactor. The effects of reaction temperature, CH₄ percent, particle size and sample mass on reduction were discussed and an appropriate condition was determined by contrastive experiments. The results show that Ni-Fe mixed additive greatly improves the reactivity of CaSO₄, and the suitable reaction temperature is around 925℃. Carbon deposition is inhibited and higher gas conversion is obtained by lower CH₄ percent and more sample mass. However, the sample particle size has a little effect on the reduction. The long-time reduction-oxidation test demonstrates that compound CaSO₄ oxygen carrier has a higher conversion. X-ray diffraction analysis reveals that CaSO₄ could be fully reduced into CaS which is also almost oxidized into CaSO₄.