CaxLa1-xMn1-yMyO3-δ (M = Mg, Ti, Fe, or Cu) as Oxygen Carriers for Chemical-Looping with Oxygen Uncoupling (CLOU)

Perovskite materials of the type CaxLa1-xMn1-yMyO3-delta (M = Mg, Ti, Fe, or Cu) have been investigated as oxygen carriers for the chemical-looping with oxygen uncoupling (CLOU) process. The oxygen carrier, particles were Produced by mechanical homogenization of primary solids in a rotary, evaporator, followed by extrusion and calcination, at 1300 degrees C for 6 h. The chemical-looping characteristics of the substituted perovskites developed in this work were evaluated in a laboratory-scale fluidized-bed reactor in the temperature range of 900-1000 degrees C during alternating reducing and oxidizing conditions. The oxygen carriers showed oxygen releasing behaviour (CLOU) in an inert atmosphere between 900 and 1000 degrees C. In addition, their reactivity with methane was high, approaching complete gas yield for all of the materials at 950 degrees C, with the exception being the Cu-doped perovskite, which defluidized during reduction. The rates of oxygen release were also investigated using devolatilized wood char as solid were found to be similar. The required solids inventory in the fuel reactor for the perovskite oxygen carriers is estimated to be 325 kg/MWth. All of the formulation exhibited high rates of oxidation and a high degree of stability, with no particle fragmentation or agglomeration. The high reactivity and favourable oxygen uncoupling properties make these oxygen carriers promising candidates for the CLOU process.