Developing magnetic, durable, agglomeration resistant and reactive copper-based oxygen carrier particles by promoting a kaolin-reinforced, manganese‑iron mixed oxide support

Chemical looping with oxygen uncoupling (CLOU) process, involves the use of two interconnected fluidized bed reactors, where oxygen carrier particles are able to release O2 at the fuel reactor operation conditions. Cu-based oxygen carriers containing a kaolin-reinforced MnFe mixed oxide as magnetic support, were prepared by granulation to improve their oxygen carrier properties by means of a simplified preparation method. A study was performed into the effect of kaolin concentration and calcination temperature on magnetic permeability, crushing strength, attrition, agglomeration resistance, and reactivity. Two oxygen carriers containing 28.5 wt% CuO-5 wt% kaolin and 30 wt% CuO-7.5 wt% kaolin, respectively, and both calcined at 1100 °C, were selected because they maintained their magnetic properties and reactivity after kaolin addition and showed improvement in their mechanical resistance. They were tested in a batch fluidized bed reactor (BFBR) to evaluate their fluidization behaviour. Low attrition rate without any agglomeration phenomena was observed for both of oxygen carriers up to temperature of 950 °C. The material prepared with 7.5 wt% kaolin demonstrated improved mechanical resistance, very low attrition rate and higher CuO utilization for the CLOU process after use in the BFBR, while maintaining reactivity during redox cycles and magnetic properties without agglomeration problems.