Abstract：Through mechanical-mixing method, the oxygen carriers were prepared with phosphor gypsum(PG) as an active component and bentonite(Ben) as an inert support. In order to improve their reactivity, PG-Ben oxygen carriers decorated with Ni,Cu,Fe were prepared by mechanical mixing-impregnation method. The physical and chemical properties of these oxygen carriers were characterized by X ray diffraction and N₂ absorption-desorption measurements. The reactivity of these oxygen carriers in coal chemical looping combustion was performed in a fluidized bed reactor. The results show that the reactivity of the decorated oxygen carriers is improved as its surface area increases and Ni-PG-Ben oxygen carriers exhibit better performance than the others. The reactivity of NiPG-Ben oxygen carriers is enhanced by the increase of impregnation increment. The volume fraction of CO₂ is above 80% in 12 cycles. The carbon conversion rate decreases from 0.114 min^-1 in the first redox test to 0.077 min^-1 in the fifteenth redox test. The performance of Ni-PG-Ben oxygen carrier decreases because of the generated CaNiSi₄O₁₀ which does not have catalysis effect and the loss of Ni which can catalyze the process of coal gasification.

Keywords: coal; phosphor gypsum; chemical-looping combustion; oxygen carrier; fluidized bed