Mn–Fe Oxides with Support of MgAl2O4, CeO2, ZrO2 and Y2O3–ZrO2 for Chemical-Looping Combustion and Chemical-Looping with Oxygen Uncoupling

The feasibility of utilizing a combined oxide (Mn 0.75 Fe 0.25 ) 2 O 3 as an oxygen carrier for chemical-looping with oxygen uncoupling (CLOU) has been investigated. To increase the strength and attrition resistance of such particles, the oxygen carrier was prepared together with MgAl 2 O 4, CeO 2, ZrO 2 and Y 2 O 3 –ZrO 2 as supports. The oxygen-carrier particles were prepared using spray-drying. Each material was calcined for 4 h at 950, 1100 or 1200 °C. The materials were studied in a batch fluidized bed reactor to investigate their oxygen release and uptake potential and also their reactivity with CH 4 and syngas. To gauge the mechanical stability of the different materials, the attrition resistance was measured in a jet-cup apparatus. With the exception of the material with MgAl 2 O 4, the oxygen uncoupling property of the active combined oxides was largely kept intact using the added support materials. On the basis of the results from the reactivity tests and the measured attrition rates for all the particles, the material utilizing ZrO 2 support seems to be the most promising candidate as an oxygen carrier for gaseous and solid fuels. However, due to phase transformations of the ZrO 2 at higher temperatures, the calcination and operational temperature should likely not exceed 950 °C.